Water described as "hard" or hard water scale is high in dissolved minerals, specifically calcium and magnesium. Over time hard water will shorten the life of your home appliances, hot water heaters, boilers etc. As water moves through soil and rock, it dissolves small amounts of minerals and holds them in solution. Calcium and magnesium dissolve in water and are the two most common minerals that make water "hard". The degree of hardness becomes greater as the calcium and magnesium content increases.
Hard water is not generally harmful, but a nuisance because of mineral buildup on fixtures and poor soap and/or detergent performance. Now that we have defined hard water, do you see any of these problems with your water?
Water softeners are used in water treatment to remove calcium and magnesium from the water to create soft water, prevent calcium or scale buildup, resolve hair and skin issues and make soaps more efficient. A water softener is an investment that can help you save money and reduce your stress.
Clothes washed in hard water often look dingy and feel harsh or scratchy. The hardness minerals combine with some soils to form insoluble salts, making them difficult to remove. Soil on clothes can introduce even more hardness minerals into your water. Continuous laundering in hard water can damage fibers and shorten the life of clothes by up to 40%.
Bathing with soap in hard water leaves a film of sticky soap curd on the skin. The film may prevent the removal of soil and bacteria. Soap curd interferes with the return of skin to its normal, slightly acidic condition and may lead to irritation. Soap curd on hair can make it dull, lifeless and difficult to manage. It can also cause clogging of shower heads and results in poor water pressure.
When washing dishes, especially in a dishwasher, hard water can mar the surface of your glass, crockery, silverware and pots. The minerals from hard water are released faster when it comes into contact with heat, causing an increase in the amount of spotting and filming occurring on your dishes. It is not so much a health risk, but a nuisance.
Boiler Systems and Piping
Hard water also contributes to insufficient and costly operation of water using appliances. Heated hard water forms a scale of calcium and magnesium minerals (lime scale deposits) that can contribute to the inefficient operation or failure of water using appliances. Pipes can become clogged with scale that reduces water flow and ultimately will require pipe replacement. Lime scale has been known to increase energy bills by up to 25%.
Acidic water can cause your copper piping to deteriorate and cause small pinholes which can lead to water damage. Most piping is located inside walls which would cost a considerable amount of money to repair walls, ceilings and flooring as a result of water damage. Proper water treatment will prevent these costly repairs.
Iron is a major problem in many rural water sources. It stains laundry, fixtures and water-using appliances with a reddish-brown colour and causes an objectionable taste in foods and beverages. In well water, iron usually occurs in its ferrous state. The water is clear when freshly drawn, but once exposed to air the iron will oxidize and go into a ferric state. It will be seen as red discoloured water and forms insoluble rust particles. Concentrations above 0.3 mg/litre will cause staining. Iron bacteria can form and it feeds on the iron in the water, on water system components, and adds even more iron to the water. These living organisms can be identified as a rusty coloured slime in toilet tanks. They do not present a health risk, but can clog pipes and valves. This bacteria can usually be controlled with regular shock chlorination of the well and water system. The iron bacteria can be controlled, but cannot be completely eliminated with periodic treatments, as needed.
If any of these problems are present with your water, you need a Clear Blue Iron Filter! Used in water treatment to remove heavy metals, odours and colours, this filter stops reddish to brown coloured water from staining your laundry. It also prevents red slime in tanks and clogging of piping. The iron bacteria cannot be completely eliminated, but can be controlled with periodic treatments, as needed.
SOCs (Synthetic Organic Compounds)
TOCs (Total Organic Compounds)
TDS (Total Dissolved Solids)
If you want clean water, Clear Blue Water Systems is your clear choice.
Just give us a call and we can help you with any water issues you have!
All of the below water quality issues are correctable by Clear Blue Water treatment systems and components. For outside our service areas we will bed and ship any required water filer, ready to use to your location.
The Canadian Drinking Water Guidelines are available at http://www.hc-sc.gc.ca/ewh-semt/water-eau/drink-potab/guide/index-eng.php.
Source of Acidic Water: Acidic waters usually attain their acidity from the seepage of acid mine waters, or acidic industrial wastes. Acid mine waters are frequently too low in pH to provide suitable drinking water even after neutralization and treatment.
Treatment of Acidic Water: Acidic water can be corrected by injecting soda ash or caustic soda (sodium hydroxide) into the water supply to raise the pH. Utilization of these two chemicals slightly increases the alkalinity in direct proportion to the amount used. Acidic water can also be neutralized up to a point by running it through calcite, corosex or a combination of the two. The calcite and the corosex both neutralize by dissolving and they add hardness to the water as the neutralization takes place; therefore, they both need to be replenished on a periodic basis.
Source of Aluminum: Aluminum (Al+3) is an abundant metal in the Earth's surface, but its solubility in water is so low that it is seldom a concern in municipal or industrial water systems. The majority of natural water contains from 0.1 ppm up to 9.0 ppm of aluminum; however, the primary Source of aluminum in drinking water comes from the use of aluminum sulfate (alum) as a coagulant in water treatment plants. The total dietary exposure to aluminum salts averages around 20 mg/day. Per Canadian Drinking Water Standards, the maximum allowable limit of aluminum is 0.1 mg/L .
Treatment of Aluminum: Aluminum can be removed from water by a cation exchanger but hydrochloric acid or sulfuric acid must be used for regeneration to remove the aluminum from the resin. While this is suitable for an industrial application it is not recommended for domestic use unless it is in the form of a cation exchange tank. Reverse osmosis will reduce the aluminum content of drinking water by 98%. Distillation will reduce the aluminum content of water by 99%. Electrodialysis is also very effective in the reduction of aluminum.
Source of Ammonia: Ammonia (〖"NH" 〗_3) gas, usually expressed as Nitrogen, is extremely soluble in water. It is the natural product of decay of organic nitrogen compounds. Ammonia finds its way into surface supplies from the runoff in agricultural areas where it is applied as fertilizer. It can also find its way to underground aquifers from animal feed lots. Ammonia is oxidized to nitrate by bacterial action. A concentration of 0.1 to 1.0 ppm is typically found in most surface water supplies, and is expressed as N. Ammonia is not usually found in well water supplies because the bacteria in the soil converts it nitrates. The concentration of Ammonia is not restricted by drinking water standards. Since Ammonia is corrosive to copper alloys it is a concern in cooling systems and in boiler feed.
Treatment of Ammonia: Ammonia can be destroyed chemically by chlorination. The initial reaction forms chloramine, and must be completely broken down before there is a chlorine residual. The chlorine will destroy organic contaminants in the waste stream before it will reach with the ammonia. Ammonia can also be removed by cation exchange resin in the hydrogen form, which is the utilization of acid as a regenerant. Degasification will also remove Ammonia.
Source of Arsenic: Arsenic (As) is not easily dissolved in water, therefore, if it is found in a water supply, it usually comes from mining or metallurgical operations or from runoff from agricultural areas where materials containing arsenic were used as industrial poisons. Arsenic and phosphate easily substitute for one another chemically, therefore commercial grade phosphate can have some arsenic in it. Arsenic is highly toxic and has been classified by the Canadian Drinking Water Standards as a carcinogen. The current maximum allowable limit for arsenic is 0.01 mg/l, which was derived from toxicity considerations rather than carcinogenicity.
Treatment of Arsenic: If in an inorganic form, arsenic can be removed or reduced by conventional water treatment processes. There are five ways to remove inorganic contaminants; reverse osmosis, activated alumina, ion exchange, activated carbon, and distillation. Filtration through activated carbon will reduce the amount of arsenic in drinking water from 40 - 70%. Anion exchange can reduce it by 90 - 100%. Reverse Osmosis has a 90% removal rate, and Distillation will remove 98%. If the arsenic is present in organic form, it can be removed by oxidation of the organic material and subsequent coagulation.
Source of Bacteria: Bacteria are tiny organisms occurring naturally in water. Not all types of bacteria are harmful. Many organisms found in water are of no health concern since they do not cause disease. Biological contamination may be separated into two groups: (1) pathogenic (disease causing) and (2) non-pathogenic (not disease causing). Pathogenic bacteria cause illnesses such as typhoid fever, dysentery, gastroenteritis, infectious hepatitis, and cholera. All water supplies should be tested for biological content prior to use and consumption. E.Coli (Escherichia Coli) is the coliform bacterial organism which is looked for when testing the water. This organism is found in the intestines and fecal matter of humans and animals. If E.Coli is found in a water supply along with high nitrate and chloride levels, it usually indicates that waste has contaminated the supply from a septic system or sewage dumping, and has entered by way of runoff, a fractured well casing, or broken lines. If coliform bacteria is present, it is an indication that disease causing bacteria may also be present. Four or fewer colonies / 100 ml of coliforms, in the absence of high nitrates and chlorides, implies that surface water is entering the water system. The most common non-pathogenic bacteria found in water, is iron bacteria. Iron bacteria can be readily identified by the red, feathery floc which forms overnight at the bottom of a sample bottle containing iron and iron bacteria.
Treatment of Bacteria: Bacteria can be treated by microfiltration, reverse osmosis, ultra filtration, or chemical oxidation and disinfection. Ultraviolet sterilization will also kill bacteria; but turbidity, colour, and organic impurities interfere with the transmission of ultraviolet energy and may decrease the disinfection efficiency below levels to insure destruction. Ultraviolet treatment also does not provide residual bactericidal action, therefore periodic flushing and disinfection must be done. Ultraviolet sterilization is usually followed by 0.2 micron filtration when dealing with high purity water systems. The most common and undisputed method of bacteria destruction is chemical oxidation and disinfection. Ozone injection into a water supply is one form of chemical oxidation and disinfection. A residual of 0.4 mg/l must be established and a retention time of four minutes is required. Chlorine injection is the most widely recognized method of chemical oxidation and disinfection. Chlorine must be fed at 3 to 5 ppm to treat for bacteria and a residual of 0.4 ppm of free chlorine must be maintained for 30 minutes in order to meet Canadian Drinking Water Standards. Reverse Osmosis will remove 99+ % of the bacteria in a drinking water system.
Source of Barium: Barium (〖"Ba" 〗^"+2" ) is a naturally occurring alkaline earth metal. Traces of the element are found in surface and ground waters. It can also be found in oil and gas drilling muds, waste from coal fired power plants, jet fuels, and automotive paints. Barium is highly toxic when its soluble salts are ingested. The current maximum allowable limit for Barium is 1.0 mg/l.
Treatment of Barium: Sodiumform cation exchange units (softeners) are very effective at removing Barium. Reverse Osmosis is also extremely effective in its removal, as well as Electrodialysis.
Source of Benzene: Benzene, a byproduct of petroleum refining, is used as an intermediate in the production of synthesized plastics, and is also an additive in gasoline. Gasoline contains approximately 0.8 percent benzene by volume. Benzene is classified as a volatile organic chemical (VOC) and is considered a carcinogen by Canadian Drinking Water Standards. Benzene makes its way into water supplies from leaking fuel tanks, industrial chemical waste, pharmaceutical industry waste, or from run off of pesticides. The current Canadian Drinking Water Standardsmaximum allowable limit for Benzene is 0.005 mg/l.
Treatment of Benzene: Benzene can be removed with activated carbon. Approximately 1000 gallons of water containing 570 ppb of benzene can be treated with 0.35 lbs of activated carbon, in other words; 94,300 gallons of water can be treated for every cubic foot of carbon. The benzene must be in contact with the carbon for a minimum of 10 minutes. If the required flow rate is 5 gpm, then 50 gallon of carbon is required; which converts to approx. 7 cu. ft. The activated carbon must be replaced when exhausted.
Source of Bicarbonate: The Bicarbonate (〖"HCO" 〗_"3" ) ion is the principal alkaline constituent in almost all water supplies. Alkalinity in drinking water supplies seldom exceeds 300 mg/l. Bicarbonate alkalinity is introduced into the water by 〖"CO" 〗_"2" dissolving carbonate-containing minerals. Alkalinity control is important in boiler feed water, cooling tower water, and in the beverage industry. Alkalinity neutralizes the acidity in fruit flavors; and in the textile industry, it interferes with acid dying. Alkalinity is known as a "buffer".
Treatment of Bicarbonate: In the pH range of 5.0 to 8.0 there is a balance between excess 〖"CO" 〗_"2" and bicarbonate ions. Removing the free 〖"CO" 〗_"2" through aeration can reduce the bicarbonate alkalinity. Feeding acid to lower the pH can also reduce the alkalinity. At pH 5.0 there is only 〖"CO" 〗_"2" and 0 alkalinity. A strong base anion exchanger will also remove alkalinity.
Source of Borate (Boron): Borate B(〖"OH" 〗_"4" ) is a compound of Boron. Most of the world's boron is contained in sea water. Sodium borate occurs in arid regions where inland seas once existed but have long since evaporated. Boron is frequently present in fresh water supplies in these same areas in the form of non-ionized boric acid. The amount of boric acid is not limited by drinking water standards, but it can be damaging to citrus crops if it is present in irrigation water and becomes concentrated in the soil. Canadian Drinking Water Standards maximum allowable limit for Boron is 5.0 mg/l.
Treatment of Borate (Boron): Boron behaves like silica when it is in an aqueous solution. It can be removed with an Anion Exchanger or adsorbed utilizing an Activated Carbon Filter.
Source of Bromine (Bromide):Bromine is found in sea water and exists as the bromide ion at a level of about 65 mg/l. Bromine has been used in swimming pools and cooling towers for disinfection, however use in drinking water is not recommended. Ethylene bromide is used as an anti-knock additive in gasoline, and methyl bromide is a soil fumigant. Bromine is extremely reactive and corrosive, and will produce irritation and burning to exposed tissues. Over 0.05 mg/l in fresh water may indicate the presence of industrial wastes, possibly from the use of pesticides of biocides containing bromine. Bromide is extensively used in the pharmaceutical industry, and occurs normally in blood in the range of 1.5 to 50 mg/l.
Treatment of Bromine (Bromide): Reverse Osmosis will remove 93 -96 % of the bromide from drinking water. Since bromine is a disinfectant, it along with the disinfection by-products can also be removed with Activated Carbon, Ultra filtration, or Electrodialysis.
Source of Cadmium: Cadmium enters the environment through a variety of industrial operations, it is an impurity found in zinc. By-products from mining, smelting, electroplating, pigment, and plasticizer production can contain cadmium. Cadmium emissions come from fossil fuel use. Cadmium makes its way into the water supplies as a result of deterioration of galvanized plumbing, industrial waste or fertilizer contamination. Canadian Drinking Water Standards lists Cadmium with a 0.005 mg/l maximum allowable limit.
Treatment of Cadmium: Cadmium can be removed from drinking water with a sodium form cation exchanger (softener). Reverse Osmosis will remove 95 - 98 % of the cadmium in the water. Electro dialysis will also remove the majority of the cadmium.
Source of Calcium: Calcium is the major component of hardness in water and is usually in the range of 5 - 500 mg/l, as 〖"CaCO" 〗_"3" . Calcium is derived from nearly all rock, but the greatest concentrations come from limestone and gypsum. Calcium ions are the principal cations in most natural waters. Calcium reduction is required in treating cooling tower makeup. Complete removal is required in metal finishing, textile operations, and boiler feed applications.
Treatment of Calcium: Calcium, as with all hardness, can be removed with a simple sodium form cation exchanger (softener). Reverse Osmosis will remove 95 - 98 % of the calcium in the water. Electrodialysis and Ultrafiltration also will remove calcium. Calcium can also be removed with the hydrogen form cation exchanger portion of a deionizer system.
Source of Carbon Dioxide: Free carbon dioxide (〖"CO" 〗_"2" ) exists in varying amounts in most natural water supplies. Most well waters will contain less than 50 ppm. Carbon Dioxide in water yields an acidic condition. Water ("H" _"2" "O" ) plus carbon dioxide (〖"CO" 〗_"2" ) yields carbonic acid ("H" _"2" 〖"CO" 〗_"3" ). The dissociation of carbonic acid yields hydrogen (H) and bicarbonate alkalinity (〖"HCO" 〗_"3" ). The pH value will drop as the concentration of carbon dioxide increases, and conversely will increase as the bicarbonate alkalinity content increases.
"H" _"2" "O" + 〖"CO" 〗_"2" <====> "H" _"2" 〖"CO" 〗_"3" <====> H+ + 〖"HCO" 〗_"3"
Water with a pH of 3.5 or below generally, contains mineral acids such as sulfuric or hydrochloric acid. Carbon Dioxide can exist in waters with pH values from 3.6 to 8.4, but will never be present in waters having a pH of 8.5 or above. The pH value is not a measurement of the amount of carbon dioxide in the water, but rather the relationship of carbon dioxide and bicarbonate alkalinity.
Treatment of Carbon Dioxide: Free 〖"CO" 〗_"2" can be easily dissipated by aeration. A two column deionizer (consisting of a hydrogen form strong acid cation and a hydroxide form strong base anion) will also remove the carbon dioxide. The cation exchanger adds the hydrogen ion (H+) which shifts the above equation to the left in favor of water and carbon dioxide release. The anion resin removes the carbon dioxide by actually removing the bicarbonate ion. A forced draft degasifier placed between the cation and anion will serve to blow off the 〖"CO" 〗_"2" before it reaches the anion bed, thus reducing the capacity requirements for the anion resin. The 〖"CO" 〗_"2" can be eliminated by raising the pH to 8.5 or above with a soda ash or caustic soda chemical feed system.
Source of Carbon Tetrachloride: Carbon tetrachloride (〖"CC" 〗_"14" ) is a volatile organic chemical (VOC), and is primarily used in the manufacture of chlorofluoromethane but also in grain fumigants, fire extinguishers, solvents, and cleaning agents. Many water supplies across the country have been found to contain measurable amounts of VOC's. VOC's pose a possible health risk because a number of them are probable or known carcinogens. The detection of VOC's in a water supply indicates that a pollution incident has occurred, because these chemicals are man-made. See Volatile Organic Chemicals for a complete listing. The Canadian Drinking Water Standards has classified carbon tetrachloride as a probable human carcinogen and established an maximum allowable limit of 0.010 mg/l.
Treatment of Carbon Tetrachloride: Reverse Osmosis will remove 70 to 80% of the VOC's in drinking water as will ultrafiltration and electrodialysis. Carbon tetrachloride as well as the other volatile organic chemicals (VOC's) can also be removed from drinking water with activated carbon filtration. The adsorption capacity of the carbon will vary with each type of VOC. The carbon manufacturers can run computer projections on many of these chemicals and give an estimate as to the amount of VOC which can be removed before the carbon will need replacement.
Source of Chloride: Chloride (〖"Cl" 〗^"-1" ) is one of the major anions found in water and are generally combined with calcium, magnesium, or sodium. Since almost all chloride salts are highly soluble in water, the chloride content ranges from 10 to 100 mg/l. Sea water contains over 30,000 mg/l as NaC1. Chloride is associated with the corrosion of piping because of the compounds formed with it; for example, magnesium chloride can generate hydrochloric acid when heated. Corrosion rates and the iron dissolved into the water from piping increases as the sodium chloride content of the water is increased. The chloride ion is instrumental in breaking down passivating films which protect ferrous metals and alloys from corrosion, and is one of the main causes for the pitting corrosion of stainless steel. Chloride impacts an objectionable salty taste in drinking water above concentrations of 250 mg/l, and may cause corrosion in water distribution systems.
Treatment of Chloride: Reverse Osmosis will remove 90 - 95% of the chlorides because of its salt rejection capabilities. Electrodialysis and distillation are two more processes which can be used to reduce the chloride content of water. Strong base anion exchanger which is the later portion of a two-column deionizer does an excellent job at removing chlorides for industrial applications.
Source of Chlorine: Chlorine is the most commonly used agent for the disinfection of water supplies. Chlorine is a strong oxidizing agent capable of reacting with many impurities in water including ammonia, proteins, amino acids, iron, and manganese. The amount of chlorine required to react with these substances is called the chlorine demand. Liquid chlorine is sodium hypochlorite. Household liquid bleach is 5% sodium hypochlorite. Chlorine in the form of a solid is calcium hypochlorite. When chlorine is added to water, a variety of chloro-compounds are formed. An example of this would be when ammonia is present, inorganic compounds known as chloramines are produced. Chlorine also reacts with residual organic material to produce potentially carcinogenic compounds, the Trihalomethanes (THM's): chloroform, bromodichloromethane, bromoform, and chlorodibromomethane. THM regulations has required that other oxidants and disinfectants be considered in order to minimize THM formation. The other chemical oxidants being examined are: potassium permanganate, hydrogen peroxide, chloramines, chlorine dioxide, and ozone. No matter what form of chlorine is added to water, hypochlorite, hypochlorous acid, and molecular chlorine will be formed. The reaction lowers the pH, thus making the water more corrosive and aggressive to steel and copper pipe.
Treatment of Chlorine: Chlorinated water can be dosed with sulfite-bisulfite-sulfur dioxide or passed through a activated carbon filter. Activated carbon will remove 880,000 ppm of free chlorine per cubic foot of media.
Source of Chromium: Chromium is found in drinking water as a result of industrial waste contamination. The occurrence of excess chromium is relatively infrequent. Proper tests must be run on the water supply to determine the form of the chromium present. Trivalent chromium (〖"Cr" 〗^"-3" ) is slightly soluble in water, and is considered essential in man and animals for efficient lipid, glucose, and protein metabolism. Hexavalent chromium (〖"Cr" 〗^"-6" ) on the other hand is considered toxic. The Canadian Drinking Water Standards classifies chromium as a human carcinogen and max allowable content .05 mg/l.
Treatment of Chromium: Trivalent chromium (〖"Cr" 〗^"-3" ) can be removed with strong acid cation resin regenerated with hydrochloric acid. Hexavalent chromium (〖"Cr" 〗^"-6" ) on the other hand requires the utilization of a strong base anion exchanger which must be regenerated with caustic soda (sodium hydroxide) NaOH. Reverse Osmosis can effectively reduce both forms of chromium by 90 to 97%. Distillation will also reduce chromium.
Source of Colour: Colour in water is almost always due to organic material which is usually extracted from decaying vegetation. Colour is common in surface water supplies, while it is virtually non-existent in spring water and deep wells. Colour in water may also be the result of natural metallic ions (iron and manganese). A yellow tint to the water indicates that humic acids are present, referred to as "tannins". A reddish colour would indicate the presence of precipitated iron. Stains on bathroom fixtures and on laundry are often associated with colour also. Reddish-brown is ferric hydroxide (iron) will precipitate when the water is exposed to air. Dark brown to black stains are created by manganese. Excess copper can create blue stains.
Treatment of Colour: Colour is removed by chemical feed, retention and filtration. Activated carbon filtration will work most effectively to remove colour in general. Anion scavenger resin will remove tannins, but must be preceded by a softener or mixed with fine mesh softener resin. See the headings Iron, Manganese, and Copper for information their removal or reduction.
Source of Copper: Copper (〖"Cu" 〗^"-3" ) in drinking water can be derived from rock weathering, however the principal sources are the corrosion of brass and copper piping and the addition of copper salts when treating water supplies for algae control. The body for proper nutrition requires copper. Insufficient amounts of copper leads to iron deficiency. However, high doses of copper can cause liver damage or anemia. The taste threshold for copper in drinking water is 1.0 mg/l under the Canadian Drinking Water Standards.
Treatment of Copper: Copper can be reduced or removed with sodium form strong acid cation resin (softener) dependent on the concentration. If the cation resin is regenerated with acid performance will be enhanced. Reverse osmosis or electrodialysis will remove 97 - 98 % of the copper in the water supply. Activated carbon filtration will also remove copper by adsorption.
Source of Cryptosporidium: Cryptosporidium is a protozoan parasite which exists as a round oocyst about 4 to 6 microns in diameter. Oocysts pass through the stomach into the small intestine where its sporozoites invade the cell lining of the gastrointestinal tract. Symptoms of infection include diarrhea, cramps, nausea, and low-grade fever.
Treatment of Cryptosporidium: Filtration is the most effective treatment for protozoan cysts. Cartridge POU filters rated at 0.5 micron are designed for this purpose.
Source of Cyanide: Cyanide (CN) is extremely toxic and is not commonly found at significant levels in drinking water. Cyanide is normally found in waste water from metal finishing operations. Maximum allowable content of cyanide is sat at 0.2 mg/l by the Canadian Drinking Water Standards.
Treatment of Cyanide: Chlorine feed, retention, and filtration will break down the cyanide. Reverse Osmosis or Electrodialysis will remove 90 - 95 % of it.
Source of Fluoride: Fluoride ("F" ^"+" ) is a common constituent of many minerals. Municipal water treatment plants commonly add fluoride to the water for prevention of tooth decay, and maintain a level of 1.5 - 2.5 mg/l. Concentrations above 5 mg/l are detrimental to tooth structure. High concentrations are contained in waste water from the manufacture of glass and steel, as well as from foundry operations. Organic fluorine is present in vegetables, fruits, and nuts. Inorganic fluorine, under the name of sodium fluoride, is a waste product of aluminum and is used in some rat poisons. Canadian Drinking Water Standards for fluoride are 1.5 mg/l maximum allowable limit.
Treatment of Fluoride: Fluoride can be reduced by anion exchange. Adsorption by calcium phosphate, magnesium hydroxide or activated carbon will also reduce the fluoride content of drinking water. Reverse osmosis will remove 93 - 95 % of the fluoride.
Source of Giardia Lamblia: Giardia is a protozoan which can exist as a trophozoite, usually 9 to 21 tm long, or as an ovoid cyst, approximately 10 um long and 6 um wide. Protozoans are unicellular and colourless organisms that lack a cell wall. When Giardia are ingested by humans, symptoms include diarrhea, fatigue, and cramps.
Treatment of Giardia Lamblia: Slow sand filtration or a diatomaceous earth filter can remove up to 99 % of the cysts when proper pretreatment is utilized. Chemical, ultrafiltration, and reverse osmosis all effectively remove Giardia cysts. Ozone appears to be very effective against the cysts when utilized in the chemical oxidation - disinfection process instead of chlorine. The most economical and widely used method of removing Giardia is mechanical filtration. Because of the size of the parasite, it can easily be removed with precoat, solid block carbon, ceramic, pleated membrane, and spun wrapped filter cartridges.
Source of Hardness: Hard water is found over 80% of Canadian water. The hardness of a water supply is determined by the content of calcium and magnesium salts. Calcium and magnesium combine with bicarbonates, sulfates, chlorides, and nitrates to form these salts. The standard domestic measurement for hardness is grains per gallon (gpg) as 〖"CaCO" 〗_"3" . Water having a hardness content less than 0.6 gpg is considered commercially soft. The calcium and magnesium salts which form hardness are divided into two categories: 1) Temporary Hardness (containing carbonates), and 2) Permanent Hardness (containing non-carbonates). Below find listings of the various combinations of permanent and temporary hardness along with their chemical formula and some information on each.
Temporary Hardness Salts
Treatment of Hardness: Softeners can remove compensated hardness up to a practical limit of 100 gpg. If the hardness is above 30 gpg or the sodium to hardness ratio is greater than 33%, then economy salt settings cannot be used. If the hardness is high, then the sodium will be high after softening, and may require that reverse osmosis be used for producing drinking water.
Source of Hydrogen Sulfide: Hydrogen Sulfide ("H" _"2" "S" ) is a gas which imparts its "rotten egg" odor to water supplies. Such waters are distasteful for drinking purposes and processes in practically all industries. Most sulfur waters contain from 1 to 5 ppm of hydrogen sulfide. Hydrogen sulfide can interfere with readings obtained from water samples. It turns hardness and pH tests gray, and makes iron tests inaccurate. Chlorine bleach should be added to eliminate the "H" _"2" "S" odor; then the hardness, pH and iron tests can be done. Hydrogen sulfide can not be tested in a lab, it must be done in the field. Hydrogen sulfide is corrosive to plumbing fixtures even at low concentrations. "H" _"2" "S" fumes will blacken or darken painted surfaces, giving them a "smoked" appearance.
Treatment of Hydrogen Sulfide: H2S requires chlorine to be fed in sufficient quantities to eliminate it, while leaving a residual in the water (3 ppm of chlorine is required for each ppm of hydrogen sulfide). Activated carbon filtration may then be installed to remove the excess chlorine. A second option is a manganese greensand filter to remove the "H" _"2" "S" .
Source of Lead: Lead (Pb2) found in fresh water usually indicates contamination from metallurgical wastes or from lead-containing industrial poisons. Lead in drinking water is primarily from the corrosion of the lead solder used to put together the copper piping. Lead in the body can cause serious damage to the brain, kidneys, nervous system, and red blood cells. The Canadian Drinking Water Standardsconsiders lead to be a highly toxic metal and a major health threat. The current level of lead allowable in drinking water is 0.01 mg/L.
Treatment of Lead: Lead can be reduced considerably with a water softener. Activated carbon filtration can also reduce lead to a certain extent. Reverse osmosis can remove 94 to 98 % of the lead in drinking water at the point-of-use. Distillation will also remove the lead from drinking water.
Source of Legionella: In July 1976, there was an outbreak of pneumonia effecting 221 people attending the annual Pennsylvania American Legion convention at the Bellvue-Stratford Hotel in Philadelphia. Out of the 221 people infected, 34 died. It wasn't until December 1977 that microbiologists were able to isolate a bacterium from the autopsy of the lung tissue of one of the legionnaires. The bacterium was named "Legionella pneumophila" (Legionella in honor of the American Legion, and pneumophila which is Greek for "lung-loving") and was found to be completely different from other bacteria. Unlike patients with other pneumonias, patients with legionnaire's disease often have severe gastrointestinal symptoms, including diarrhea, nausea, and vomiting. The maximum allowable content of Legionella is 0 mg/L.
Treatment of Legionella: Chemical oxidation-disinfection followed by retention, then filtration could be used. Since Legionella is a bacteria, Reverse osmosis or Ultrafiltration are the preferred removal techniques.
Source of Magnesium: Magnesium (Mg+2) hardness is usually approximately 33% of the total hardness of a particular water supply. Magnesium is found in many minerals, including dolomite, magnesite, and many types of clay. It is in abundance in sea water where its concentration is five (5) times the amount of calcium. Magnesium carbonate is seldom a major component of in scale. However, it must be removed along with calcium where soft water is required for boiler make-up, or for process applications.
Treatment of Magnesium: Magnesium may be reduced to less than 1 mg/l with the use of a softener or cation exchanger in hydrogen form. Also see "Hardness".
Source of Manganese: Manganese (Mn+4, Mn+2) is present in many soils and sediments as well as in rocks whose structures have been changed by heat and pressure. It is used in the manufacture of steel to improve corrosion resistance and hardness. Manganese is considered essential to plant and animal life and can be derived from such foods as corn, spinach, and whole wheat products. It is known to be important in building strong bones and may be beneficial to the cardiovascular system. Manganese may be found in deep well waters at concentrations as high as 2 - 3 mg/l. It is hard to treat because of the complexes it can form which are dependent on the oxidation state, pH, bicarbonate-carbonate-OH ratios, and the presence of other minerals, particularly iron. Concentrations higher than 0.05 mg/l cause manganese deposits and staining of clothing and plumbing fixtures. The stains are dark brown to black in nature. The use of chlorine bleach in the laundry will cause the stains to set. The chemistry of manganese in water is similar to that of iron. A high level of manganese in the water produces an unpleasant odor and taste. Organic materials can tie up manganese in the same manner as they do iron; therefore destruction of the organic matter is a necessary part of manganese removal. The Canadian Drinking Water Standards maximum allowable content is 0.05 mg/L.
Treatment of Manganese: Removal of manganese can be done by ion exchange (sodium form cation - softener) or chemical oxidation - retention - filtration. Removal with a water softener dictates that the pH be 6.8 or higher and is beneficial to use countercurrent regeneration with brine make-up and backwash utilizing soft water. It takes 1 ppm of oxygen to treat 1.5 ppm of manganese. Greensand filter with potassium will remove up to 10 ppm if pH is above 8.0. Birm filter with air injection will reduce manganese if pH is 8.0 to 8.5. Chemical feed (chlorine, potassium permanganate, or hydrogen peroxide) followed by 20 minutes retention and then filtered with birm, greensand, carbon, or Filter Ag will also remove the manganese.
Source of Mercury: Mercury (Hg) is one of the least abundant elements in the earth's crust. It exists in two forms, an inorganic salt or an organic compound (methyl mercury). Mercury detected in drinking water is of the inorganic type. Organic mercury inters the food chain through fish and comes primarily from industrial chemical manufacturing waste or from the leaching of coal ash. If inorganic mercury inters the body, it usually settles in the kidneys, whereas organic mercury attacks the central nervous system. As mercury is toxic, the maximum allowable content has been set at 0.001 mg/L by the Canadian Drinking Water Standards.
Treatment of Mercury: Activated carbon filtration is very effective for the removal of mercury. Reverse osmosis will remove 95 - 97 % of it.
Source of Methane: Methane (CH_4), often called marsh gas, is the primary component of natural gas. It is commonly found where landfills once existed and is generated from decaying of plants or other carbon based matter. It can also be found in and around oil fields. Methane is colourless, odorless, nearly invisible, highly flammable, and often found in conjunction with other gases such as hydrogen sulfide. Even though methane gas gives water a milky appearance which makes it aesthetically unpleasant, there are no known health effects.
Treatment of Methane: Aeration or degasification is the only way to eliminate the problem of methane gas. Venting the casing and/or the cap of the well will reduce the problem of methane in the water, but may not completely eliminate it. Another method is to provide an atmospheric holding tank where the methane laden water can be vented to allow the gas to dissipate. This method may not be 100% effective either. An aerator or degasifier is the proper piece of equipment to utilize for the removal of methane. Water is introduced through the top, sometimes through spray nozzles, and allowed to percolate through a packing material. Air is forced in the opposite direction to the water flow. The water is then collected in the bottom of the unit and repressurized.
Source of Nickel: Nickel (Ni+2) is common, and exists in approximately 85% of the water supplies, and is usually around 1 ppb (part per billion).
Treatment of Nickel: Nickel behaves the same as iron, and can be removed by a strong acid cation exchanger. Activated carbon filtration can be used to reduce the amount of nickel in drinking water, but may not remove it all. Reverse osmosis will remove 97 - 98 % of the nickel from drinking water.
Source of Nitrate: Nitrate (NO_3) comes into water supplies through the nitrogen cycle rather than via dissolved minerals. It is one of the major ions in natural waters. Most nitrate that occurs in drinking water is the result of contamination of ground water supplies by septic systems, feed lots, and agricultural fertilizers. Nitrate is reduced to nitrite in the body. The Canadian Drinking Water Standards MCL for nitrate is 10 mg/L.
Treatment of Nitrate: Reverse Osmosis will remove 92 - 95% of the nitrates and/or nitrites. Anion exchange resin will also remove both as will distillation.
Source of Nitrite: Nitrites are not usually found in drinking water supplies at concentrations above 1 or 2 mg/l (ppm). Nitrates are reduced to nitrites in the saliva of the mouth and upper GI tract. This occurs to a much greater degree in infants than in adults, because of the higher alkaline conditions in their GI tract. The nitrite then oxidizes hemoglobin in the blood stream to methemoglobin, thus limiting the ability of the blood to carry oxygen throughout the body. Anoxia (an insufficiency of oxygen) and death can occur. The Canadian Drinking Water Standards has established the MCL (maximum contaminant level) for nitrite at 1 mg/L.
Treatment of Nitrite: Nitrites are removed in the same manner as nitrates; reverse osmosis, anion exchange, or distillation. See Nitrate – Treatment of Nitrate.
Source of Odor: Taste and odor problems of many different types can be encountered in drinking water. Troublesome compounds may result from biological growth or industrial activities. The tastes and odors may be produced in the water supply, in the water treatment plant from reactions with treatment chemicals, in the distribution system, and/or in the plumbing of consumers. Tastes and odors can be caused by mineral contaminants in the water, such as the "salty" taste of water when chlorides are 500 mg/l or above, or the rotten egg odor caused by hydrogen sulfide. Odor in the drinking water is usually caused by blue-green algae. Moderate concentrations of algae in the water can cause it to have a grassy, musty or spicy odor. Large quantities can cause the water to have a rotten, septic, fishy or medicinal odor. Decaying vegetation is probably the most common cause for taste and odor in surface water supplies. In treated water supplies chlorine can react with organics and cause odor problems. The contaminant effects are strictly aesthetic and a suggested Threshold Odor Number (TON) of 3 is recommended.
Treatment of Odor: Odor can be removed by oxidation-reduction or by activated carbon adsorption. Aeration can be utilized if the contaminant is in the form of a gas, such as H_2S (hydrogen sulfide). Chlorine is the most common oxidant used in water treatment, but is only partially effective on taste and odor. Potassium permanganate and oxygen are also only partially effective. Chloramines are not at all effective for the treatment of taste and odor. The most effective oxidizers for treating taste and odor are chlorine dioxide and ozone. Activated carbon has an excellent history of success in treating taste and odor problems. The life of the carbon depends on the presence of organics competing for sites and the concentration of the odor-causing compound.
Organics come from three major Sources: (1) the breakdown of naturally occurring organic materials, (2) domestic and commercial chemical wastes, and (3) chemical reactions that occur during water treatment processes. The first Source is comprised of humic materials, microorganisms, and petroleum-based aliphatic and aromatic hydrocarbons. Organics derived from domestic and commercial chemical wastes include wastewater discharges, agricultural runoff, urban runoff, and leaching from contaminated soils. Organic contaminants comprising the third source which are formed during water treatment include disinfection by-products such as THMs (Trihalomethanes), or undesirable components of piping assembly such as joint adhesives.
Treatment of Organics: Activated carbon is generally used to remove organics, colour, and taste-and-odor causing compounds. The contact time and service flow rate dictate the size of the carbon filter. When removing organics, restrict flow rates to 2 gpm per square foot of the filter bed. Reverse osmosis will remove 98 to 99% of the organics in the water. Ultrafiltration (UF) and nanofiltration (NF) have both been proven to remove organics. Anion exchange resin also retains organics, but periodically needs cleaning.
Source of Pesticides: Pesticides are common synthetic organic chemicals (SOCs). Pesticides reach surface and well water supplies from the runoff in agricultural areas where they are used. Certain pesticides are banned by the government because of their toxicity to humans or their adverse effect on the environment. Pesticides usually decompose and break down as they perform their intended function. Low levels of pesticides are found where complete breakdown does not occur. There is no Canadian Drinking Water Standards maximum contamination level (MCL) for pesticides as a total; each substance is considered separately.
Treatment of Pesticides: Activated carbon filtration is the most effective way to remove organics whether synthetic (like pesticides) or natural. Ultrafiltration will also remove organic compounds. Reverse Osmosis will remove 97 - 99% of the pesticides.
Source of pH: The term "pH" is used to indicate acidity or alkalinity of a given solution. It is not a measure of the quantity of acid or alkali, but rather a measure of the relationship of the acid to the alkali. The pH value of a solution describes its hydrogen-ion activity. The pH scale ranges between 0 and 14. Typically all natural waters fall within the range of 6.0 to 8.0 pH. A value of 7.0 is considered to be a neutral pH. Values below 7.0 are acidic and values above 7.0 are alkaline. The pH value of water will decrease as the content of CO_2increases, and will increase as the content of bicarbonate alkalinity increases. The ratio of carbon dioxide and bicarbonate alkalinity (within the range of 3.6 to 8.4) is an indication of the pH value of the water. Water with a pH value of 3.5 or below generally contains mineral acids such as sulfuric or hydrochloric acid.
Treatment of pH: The pH can be raised by feeding sodium hydroxide (caustic soda), sodium carbonate (soda ash), sodium bicarbonate, potassium hydroxide, etc. into the water stream. A neutralizing filter containing Calcite (calcium carbonate - CaCO_3) and/or Corosex (magnesium oxide - MgO) will combat low pH problems, if within the range of 5 to 6. The peak flow rate of a neutralizing filter is 6 gpm / sq. ft. Downflow filters require frequent backwashing is required to prevent "cementing of the bed". A 50 - 50 mix of the two seems to provide the best all around results. Upflow neutralizers don't experience the problem of "cementing" of the bed.
Source of Potassium: Potassium (K^+) is an alkaline metal closely related to sodium. It is seldom that one sees it analyzed separately on a water analysis. Potassium is not a major component in public or industrial water supplies. Potassium is, however, essential in a well-balanced diet and can be found in fruits such as bananas.
Treatment of Potassium: A cation exchange resin, usually in the form of a softener, can remove Potassium. It can also be reduced by 94 - 97% utilizing electrodialysis or reverse osmosis.
Source of Radium: Radium (Ra) is a radioactive chemical element which can be found in very small amounts in pitchblende and other uranium minerals. It is used in the treatment of cancer and some skin diseases. Radium 226 and radium 228 are of most concern when found in drinking water because of the effects on the health of individuals. Radium 228 causes bone sarcomas. Radium 226 induces carcinomas in the head. Radioactivity in water can be naturally occurring or can be from man-made contamination. Radiation is generally measured in curies (Ci). One curie equals 3.7 x 1010 nuclear transformations per second. A picocurie (pCi) equals 10-12 curies.
Treatment of Radium: Radium can be removed by sodium for cation exchange resin in the form of a water softener. Reverse osmosis will remove 95 - 98% of any radioactivity in the drinking water.
Source of Radon: Radon (Rn) is a radioactive gaseous chemical element formed in the atomic disintegration of radium. Radon 222 is one of the radionuclides of most concern when found in drinking water. It is a naturally occurring isotope, but can also come from man-made sources. All radionuclides are considered carcinogens, but the organs they target vary. Since radon 222 is a gas, it can be inhaled during showers or while washing dishes. There is a direct relationship between radon 222 and lung cancer. Consult the Canadian Drinking Water Guidelines – Radiological Parameters for information on radon in water.
Treatment of Radon: Radon is easily removed by aeration, since it is a gas. Carbon filtration is also very effective in removing radon.
Source of Selenium: Selenium (Se) is essential for human nutrition, with the majority coming from food. The concentration found in drinking water is usually low, and comes from natural minerals. Selenium is also a by-product of copper mining / smelting. It is used in photoelectric devises because its electrical conductivity varies with light. Naturally occurring selenium compounds have not been shown to be carcinogenic in animals. However, acute toxicity caused by high selenium intake has been observed in laboratory animals and in animals grazing in areas where high selenium levels exist in the soil. The Canadian Drinking Water Standards has established the MCL for selenium at 0.05 mg/l.
Treatment of Selenium: Anion exchange can reduce the amount of selenium in drinking water by 60 - 95%. Reverse osmosis is excellent at reduction of selenium.
Source of Silica: Silica (SiO_2) is an oxide of silicon, and is present in almost all minerals. It is found in surface and well water in the range of 1 - 100 mg/l. Silica is considered to be colloidal in nature because of the way it reacts with adsorbents. A colloid is a gelatinous substance made up of non-diffusible particles that remain suspended in a fluid medium. Silica is objectionable in cooling tower makeup and boiler feedwater. Silica evaporates in a boiler at high temperatures and then redeposits on the turbine blades. These deposits must be periodically removed or damage to the turbine will occur.
Treatment of Silica: The anion exchange portion of the demineralization process can remove silica. Reverse osmosis will reject 85 - 90% of the silica content in the water.
Source of Silver: Silver (Ag) is a white, precious, metallic chemical element found in natural and finished water supplies. Silver oxide can be used as a disinfectant, but usually is not. Chronic exposure to silver results in a blue-gray colour of the skin and organs. This is a permanent aesthetic effect. Silver shows no evidence of carcinogenicity. However, ingestion of high quantities of silver may result in argyria, a condition characterized by a blue-grey discolouration of the skin, eyes and mucus membranes.
Treatment of Silver: Silver can be reduced by 98% with distillation, up to 60% with activated carbon filtration, up to 90% with cation exchange or anion exchange (dependent on the pH), or up to 90% by reverse osmosis.
SOCs (Synthetic Organic Chemicals)Source of SOCs: Over 1000 SOCs (Synthetic Organic Chemicals) have been detected in drinking water at one time or another. Most are of no concern, but some are potentially a health risk to consumers. Below is a list of synthetic organic chemials along with the proposed MCL (maximum contamination level) in mg/l.
Treatment of SOCs: Activated carbon is generally used to remove organics. Flow rates should be restricted to 2 gpm per square foot of the filter bed. Reverse Osmosis will remove 98 to 99% of the organics in the water. Ultrafiltration (UF) and nanofiltration (NF) both will remove organics. Anion exchange resin also retains organics, but periodically needs cleaning.
Source of Sodium: Sodium (Na) is a major component in drinking water. All water supplies contain some sodium. The amount is dependent on local soil conditions. The higher the sodium content of water, the more corrosive the water becomes. A major source of sodium in natural waters is from the weathering of feldspars, evaporates and clay. Intake from food is generally the major Source of sodium, ranging from 1100 to 3300 mg/day. Persons requiring restrictions on salt intake, usually have a sodium limitation down to 500 mg/day. The amount of sodium obtained from drinking softened water is insignificant compared to the sodium ingested in the normal human diet. The amount of sodium contained in a quart of softened, 18 grain per gallon water is equivalent to a normal slice of white bread. Sodium in the body regulates the osmotic pressure of the blood plasma to assure the proper blood volume. Sodium chloride is essential in the formation of the stomach acids necessary for the digestive processes. The Canadian Drinking Water Standards maximum allowable limit for sodium is 200 mg/L.
Treatment of Sodium: Sodium can be removed with the hydrogen form cation exchanger portion of a deionizer. Reverse Osmosis will reduce sodium by 94 - 98%. Distillation will also remove sodium.
Source of Strontium: Strontium (Sr) is in the same family as calcium and magnesium, and is one of the polyvalent earth metals that shows up as hardness in the water. The presence of strontium is usually restricted to areas where there are lead ores, and its concentration in water is usually very low. Strontium sulfate is a critical reverse osmosis membrane foulant, dependent on its concentration.
Treatment of Strontium: Strontium can be removed with strong acid cation exchange resin. It can be in sodium form as in a water softener or the hydrogen form as in the cation portion of a two-column deionizer. Reverse osmosis will also reduce strontium but as stated above strontium sulfate is a membrane foulant.
Source of Sulfate: Sulfate (SO_4) occurs in almost all natural water. Most sulfate compounds originate from the oxidation of sulfite ores, the presence of shales, and the existence of industrial wastes. Sulfate is one of the major dissolved constituents in rain. High concentrations of sulfate in drinking water causes a laxative effect when combined with calcium and magnesium, the two most common components of hardness. Bacteria, which attack and reduce sulfates, cause hydrogen sulfide gas (H_2 S) to form. The Canadian Drinking Water Standards maximum allowable limit is 500 mg/L.
Treatment of Sulfate: Reverse osmosis will reduce the sulfate content by 97 - 98%. Sulfates can also be reduced with a strong base anion exchanger, which is normally the last half of a two-column deionizer.
Source of Taste: Generally, individuals have a more acute sense of smell than taste. Taste problems in water come from total dissolved solids (TDS) and the presence of such metals as iron, copper, manganese, or zinc. Magnesium chloride and magnesium bicarbonate are significant in terms of taste. Fluoride may also cause a distinct taste. Taste and odor problems of many different types can be encountered in drinking water. Troublesome compounds may result from biological growth or industrial activities. The tastes and odors may be produced in the water supply, in the water treatment plant from reactions with treatment chemicals, in the distribution system, and/or in the plumbing of consumers. Tastes and odors can be caused by mineral contaminants in the water, such as the "salty" taste of water when chlorides are 500 mg/l or above. Decaying vegetation is probably the most common cause for taste and odor in surface water supplies. In treated water supplies chlorine can react with organics and cause taste and odor problems. See "ODOR" for more information.
Treatment of Taste: Taste and odor can be removed by oxidation-reduction or by activated carbon adsorption. Aeration can be utilized if the contaminant is in the form of a gas, such as H_2 S (hydrogen sulfide). Chlorine is the most common oxidant used in water treatment, but is only partially effective on taste and odor. Potassium permanganate and oxygen are also only partially effective. Chloramines are not at all effective for the treatment of taste and odor. The most effective oxidizers for treating taste and odor are chlorine dioxide and ozone. Activated carbon has an excellent history of success in treating taste and odor problems. The life of the carbon depends on the presence of organics competing for sites and the concentration of the taste and odor-causing compound.
Source of THMs: THMs (Trihalomethanes) are produced when chlorine reacts with residual organic compounds. The four common THMs are chloroform, dibromochloromethane, dichlorobromomethane, and bromoform. There have been studies that suggest a connection between chlorination by-products and particularly bladder and possibly colon and rectal cancer. An MCL of 0.10 mg/l for total THMs exists.
Treatment of THMs: Trihalomethanes and other halogenated organics can be reduced by adsorption with an activated carbon filter.
Treatment of TOC: Procedures and suggestions for reduction of TOC is given under the heading "ORGANICS".
TDS (Total Disolved Solids)
Source of Total Dissolved Solids: Total Dissolved Solids (TDS) consist mainly of carbonates, bicarbonates, chlorides, sulfates, phosphates, nitrates, calcium, magnesium, sodium, potassium, iron, manganese, and a few others. They do not include gases, colloids, or sediment. The TDS can be estimated by measuring the specific conductance of the water. Dissolved solids in natural waters range from less than 10 mg/l for rain to more than 100,000 mg/l for brines. Since TDS is the sum of all materials dissolved in the water, it has many different mineral sources. The chart below indicates the TDS from various sources.
High levels of total dissolved solids can adversely industrial applications requiring the use of water such as cooling tower operations, boiler feed water, food and beverage industries, and electronics manufacturers. High levels of chloride and sulfate will accelerate corrosion of metals. The Canadian Drinking Water Standards has a suggested level of 500 mg/L listed as an aesthetic objective.
Treatment Total Dissolved Solids: TDS reduction is accomplished by reducing the total amount in the water. This is done during the process of deionization or with Reverse Osmosis. Electrodialysis will also reduce the TDS. AT higher levels, excessive hardness, unpalatability, mineral deposition and corrosion may occur.
Source of Turbidity: Turbidity is the term given to anything that is suspended in a water supply. It is found in most surface waters, but usually doesn't exist in ground waters except in shallow wells and springs after heavy rains. Turbidity gives the water a cloudy appearance or shows up as dirty sediment. Undissolved materials such as sand, clay, silt or suspended iron contribute to turbidity. Turbidity can cause the staining of sinks and fixtures as well as the discolouring of fabrics. Usually turbidity is measured in NTUs (nephelometric turbidity units). Typical drinking water will have a turbidity level of 0 to 1 NTU. Turbidity can also be measured in ppm (parts per million) and its size is measured in microns. Turbidity can be particles in the water consisting of finely divided solids, larger than molecules, but not visible by the naked eye, ranging in size from .001 to .150 mm (1 to 150 microns). The Canadian Drinking Water Standards has established an MCL for turbidity to be less than 1.0 NTU, because it interferes with disinfection of the water.
Treatment of Turbidity: Typically turbidity can be reduced to 75 microns with a cyclone separator, then reduced down to 20 micron with standard backwashable filter, but flow rates of 5 gpm/ sq. ft. are the recommended maximum. Turbidity can be reduced to 10 micron with a multimedia filter while providing flow rates of 15 gpm/sq. ft. Cartridge filters of various sizes are also available down into the submicron range. Ultrafiltration also reduces the turbidity levels of process water.
Source of Uranium: Uranium is a naturally occurring radionuclide. Natural uranium combines uranium 234, uranium 235, and uranium 238; however, uranium 238 makes up 99.27 percent of the composition. All radionuclides are considered carcinogens; however, the organ each attacks is different. Uranium is not a proven carcinogen but accumulates in the bones similar to the way radium does. Therefore, the Canadian Drinking Water Standards tends to classify it as a carcinogen. Uranium has been found to have a toxic effect on the human kidneys. The Canadian Drinking Water Standards maximum allowable content for uranium is 0.02 mg/L.
Treatment of Uranium: Uranium can be reduced by both cation and anion dependent upon its state. Reverse osmosis will reduce uranium by 95 to 98%. Ultrafiltration will also reduce the amount of uranium. Activated alumina can also be utilized.
Source of Viruses: Viruses are infectious organisms which range in size from 10 to 25 nanometers [1 nanometer = one billionth (〖10〗^(-9)) of a meter]. They are particles composed of an acidic nucleus surrounded by a protein shell. Viruses depend totally on living cells and lack an independent metabolism. There are over 100 types of enteric viruses. Enteric viruses are the viruses which infect humans. Enteric viruses which are of particular interest in drinking water are hepatitis A, Norwalk-type viruses, rotaviruses, adenoviruses, enteroviruses, and reoviruses. The test for coliform bacterial is widely accepted as an indication whether or not the water is safe to drink; therefore tests for viruses are not usually conducted. Major enteric viruses and their diseases are shown below.
Treatment of Viruses: Chemical oxidation / disinfection is the preferred treatment. Chlorine feed with 30 minute contact time for retention, followed by activated carbon filtration is the most widely used treatment. Ozone or iodine may also be utilized as oxidizing agents. Ultraviolet sterilization or distillation may also be used for the treatment of viruses.
VOCs (Volatile Organic Chemicals)
Source of VOCs: VOCs (Volatile Organic Chemicals) pose a possible health risk because many of them are known carcinogens. Volatile organic chemicals are man-made, therefore the detection of any of them indicates that there has been a chemical spill or other incident. Volatile organic chemicals are listed below.
Volatile Organic Chemicals (Maximum Allowable Limit – mg/l)
Treatment of VOCs: The best choice for removal of volatile organic chemicals is activated carbon filtration. The adsorption capacity of the carbon will vary with each type of VOC. The carbon manufacturers can run computer projections on many of these chemicals and give an estimate as to the amount of VOC which can be removed before the carbon will need replacement. Aeration may also be used alone or in conjunction with the activated carbon. Reverse Osmosis will remove 70 to 80% of the VOCs in the water. Electro dialysis and ultrafiltration are also capable of reducing volatile organic chemicals.
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