Table of Contents:
Introduction
Should Treatment Be Considered?
Disposal Do's and Dont's
Federal Drinking Water Quality Standards
Treatment Versus Conditioning
     Treatment and Conditioning Systems Available
     Water Treatment Limitations
Disinfection of Home Water Supplies
     Boiling
     Chlorination
     Shock Clorination
     Ultraviolet Light Disinfection
     Distillation
     Ozone Disinfection
Water Filtration Systems
     Mechanical Filtration/Turbidity Control
     Activated Carbon Filtration/Adsorption
     Oxidizing Filtration Systems
     Neutralizing Filters
     Reverse Osmosis
Iron and Manganese Removal
     Sequestration by Phosphate Feeders
     Ion-Exchange for Iron/Manganese Removal
     Oxidizing Filters for Ferrous Iron
     Chlorinator-and-Filter Units for Ferrous and Bacterial Iron
     Oxidation by Aeration
High pH Water - Alkaline Water
Ion-Exchange - Water Softening
Health Risk Water Contaminants
     Focus on Pesticides and Sythetic Organic Chemicals
     Focus on Giardiasis
     Focus on Arsenic
     Focus on Sodium
     Focus on Nitrate
     Focus on Lead
Water Treatment Equipment Testing
Bottled Water
     Distilled or Demineralized
     Drinking Water
     Natural or Spring Water
     Mineral Water
Guidelines For Buying a Treatment System
     Claims to Watch Out For
Glossary of Water Treatment Terms
References

Introduction

     When we go to the faucet for a drink of water, we expect a glass of clear, safe water. When bathing, doing laundry or using water for cooking, we also expect clean, fresh water. Although most groundwater is safe to drink and suitable for household tasks, there is growing concern about contamination of public and private water supplies.

     Due to poor techniques in applying and disposing of household, agricultural and industrial chemicals, more synthetic and volatile organic chemicals are showing up in water supplies. In mining and petroleum drilling areas, dangerous levels of metals have been detected in groundwater and surface water supplies. In a private well water testing program' conducted by the Montana State University Extension Service in 1989, 43 percent of 1400 water samples taken from private wells exceeded the federal limit of coliform bacteria. Other studies' have revealed the presence of seven pesticides in Montana groundwater.,These include the herbicides atrazine, 2,4?D, dicamba, MCPA, picloran, simazine and the insecticide aldicarb. Fortunately, the levels detected were below established guidance levels that indicate cause for health concern. On the other hand, in 1989, dry?cleaning solvents and de-greasing agents -- perchlorethylene (PCE) and trichlorethylene (TCE) - were found in wells near Bozeman, Montana, at levels 30 to 50 times the safe level.

     Even if you're on a public water supply, potential problems exist. While municipal water supplies must comply with federal drinking water standards, there may still be health?related water problems. In areas with naturally soft, acidic waters, lead may leach from piping and solders. Cadmium and zinc may enter drinking water as a result of corrosion of galvanized pipe.

     Small communities and individuals with private wells often face difficult decisions about costly drinking water treatments. Economics often prohibit construction of a central treatment system for small communities. Construction of new wells or piping water from neighboring supplies of better quality may not be feasible. For these small community water systems and for homes with private wells, in?home water treatment may be more cost effective in removing undesirable contaminants from the water.

Should Treatment Be Considered?

     Many types of water treatment and conditioning systems are available. Their effectiveness depends on the contamination to be treated. Before considering any water treatment you should follow these recommendations:

1. Have the water tested by a certified laboratory.

The only way to determine contaminant levels is to have your water tested by a certified laboratory or qualified water specialist with reliable field test equipment. If there is any doubt about how any water sample was taken or tested, re-sample the water before investing in a treatment system.
2. If possible, locate contamination sources.

Treatment of water should only be considered after every effort has been made to locate and control the source of contamination. Diverting surface water drainage away from the well may help. In other cases this may not be possible due to geological formations. If the water supply is being contaminated by feed lot run off, septic tank seepage, or improper use, storage or disposal of household and agricultural chemicals, controlling these sources may eliminate the need for continuous treatment.
3. Check well construction.

Often water contamination leads back to the well itself (Figure 1). Due to improper construction, placement or neglect, surface or ground contamination can enter the water supply (Figure 2). Persistent bacterial contamination or turbid water may indicate a cracked well casing, poor grout or bad seals. Good well construction incorporates protective features that block contamination pathways.

Well water may become contaminated by coliform bacteria from:

     Since soil is nature's medium for filtering pollutants from groundwater, it is important to maintain adequate distance between wells and potential sources of contamination. Table 1 shows the minimum recommended distance between wells and common sources of groundwater pollution.

     When locating a well, consider relative elevations and locations of septic tanks, drain fields, stockyards, and other sources of contamination. Where geological and/or well construction conditions are marginal, even greater distances should be allowed. In well construction, plastic or metal casing serves as a structural support to prevent caving of the hole and to shut out seepage of undesirable water. If plastic casing is used, it must have a metal transition section extending at least 18 feet below ground level and extending at least 18 inches above ground. The metal casing is an important guard against contamination because it prevents breakage. It also allows adequate space between the side of the casing and the earth. A tightly fitting cap should be installed at the top of the casing to prevent foreign material from entering the well (Figure 3).

     Grouting is also an important step because it prevents seepage of contaminants from the surface along the casing walls. Grouting seals the space between the side of the casing and the hole with an impermeable material - usually bentonite or concrete. Generally, every well must be sealed in this manner to at least 18 feet below ground level.

     Back siphonage of contaminants into a well from stock tanks and other contaminated water sources can occur when a domestic water supply system shares a common distribution system with these facilities. If sharing a common distribution system is unavoidable, it is important to use equipment with proper backflow preventers to guard against back siphonage.

4. Check septic system.

Since septic systems are a major source of bacteria contamination, it is important the system be properly designed, installed and maintained. A few tips to assure a safe system:

5. Eliminate sources of contamination.

Sometimes the source of contamination is local, such as a septic system, chemical spill, leaking storage tankm or drainage into a sinkhole or seepage from a feedlot. Once the source of the contamination is eliminated, groundwater will eventually cleanse itself through filtration, natural breakdown of the contaminants, dilution and movement of the contaminants away from the well.

Focus on Arsenic

     Arsenic is found naturally in rocks and soil. The presence of arsenic in water supplies may also be related to the past use of arsenic in various pesticide formulation. Arsenic is also a contaminant found in copper metal, and a residue of smelting and coal mining.

     Minor symptoms of chronic arsenic poisoning are similar to those of many common ailments, making it difficult to diagnose. This type of poisoning can make people tired, lethargic, and depressed. Other symptoms are white lines across the toenails and fingernails, weight loss, nausea and diarrhea alternating with constipation, and loss of hair. Arsenic is also a carcinogen.

     Much has been heard recently about arsenic in Montana's water supplies. Bringing this issue to the forefront is the proposed curtailment of consumptive uses of water or other activities that elevate arsenic concentration in streams. The instream standard (20 nanograms/L) is already exceeded in the Missouri, Yellowstone, and Clark Fork Rivers.

     For example, upper Missouri River water between the Three Forks and Fort Peck Reservoir now contains arsenic concentrations 500 to 2,500 times greater than the 20-nanogram standard; the Madison River's concentrations are 2,500 to 10,000 greater. A recnetly published Montana Bureau of Mines and Geology/Department of Health and Environmental Sciences study show extensive, shallow groundwater contamination in the Madison Valley - domestic wells reveal levels up to 170 micrograms/L (the standard is 50 microsgrams/L). The study identifies the problem source as long-term irrigation with Madison River water and recommends effective, relatively inexpensive domestic well treatment methods.

     Arsenic Treatment. For reduction of aresenic in drinking water the Montana Department of Health and Environmental Sciences recommends distillation and reverse osmosis. However, reverse osmosis is marginally effective against high leveles of aresenic (see Table 12) so its use should be limited to water supplies with relatively low aresenic concentrations. The use of activated alumina is also an acceptable method of arsenic treatment. Activated alumina is a granulated form of aluminum oxide. In this process, wate containing arsenic is passed through a cartridge or canister of activated alumina. The alumina absorbs the arsenic and fresh water continues to service faucet. The cartidge of activated alumina has to be replaced periodically. Water treatment specialists should be consulted for details relating to these treatments. For high levels of arsenic, alternative water sources should also be considered.

     Sodium salts are present to a greater or lesser degree in all natural waters. Their concentrations vary from a few parts per million in some surface supplies to several hundred parts per million in well supplies. Sodium varies geographically in relation to soils, major geologic formation, annual climatic patterns and the extent to which the soils have been naturally leached.

     Sodium concentration increases as total salt concentration increases as you move form the mountainous areas of wester Montana to eastern Montana. Sodium is not a toxic contaminant and standards for drinking water are ambiguous. Sodium levles below 20 ppm are considered excellent while concentrations as high as 250 ppm are considered acceptable.

     Some patients with heart disease have difficulty in excreting sodium and are put on a sodium diet. Depending on age, general health, and sex, sodium may present a problem in drinking water. If sodiumj in water exceeds 20 ppm, it is advisable to contact the family physician for an opinion. It is important to note that only about 10 percent of dietary sodium come from drinking water.

     Sodium Treatment. Reverse osmosis, distillation, or deionization are effective mthods for removing sodium from drinking and cooking water. The use of sodium-free bottled water is also an available alternative.

     What About Water Softeners and Sodium? Water softening is commonly used to condition water that is very hard. The softening process exchange calcium an magnesium ions for ions of sodium. The amount of sodium in softened water depends on the hardness of the water being softened. For each grain per gallon of hardness, 7.5 milligrams of sodium per quart of water is added. Table 17 gives some examples.

     Actually, compared to the sodium present in foods (Table 18).

     It is sometimes recommended that persons with high bloob pressure who are on a medically-supervised restricted sodium diet not drink softened water. This can be accomplished if a hard water faucet is installed to bypass the water softener or by installing the softener so it bypasses the main drinking faucet. Another way is to install a drinking water system, such as reverse osmosis or a distiller, to remove sodium from the drinking water.

Focus on Nitrate

     Many groundwaters contain small amounts of nitrate-nitrogen. Concentrations range from 0.1 ppm to 3-4 ppm in many areas. The maxiumum U.S. EPA allowable level for nitrate-nitrogen (NO₃-N) in drinking water is 10 ppm. During the 1989 well test program in Montana, nitrate-nitrogen levels greater than the 10 ppm standard were detected in about six percent of the private well waters tested. Almost half of of the nitrate-contaminated samples came from the three counties of Dainels, Judith Basin and Roosevelt.

     Nitrate contamination usually occurs in shallow wells in agricultural areas. Run-off from fertilized fields, animal containment facilities and septic tank percolation may readily affect such wells. However, some subsoils accumulate enough nitrates to leach into shallow aquifers causing increasing nitrate levels in ground water supplies (Figure 21).

     Nitrate contamination of drinking water is of concern because it affects human and livestock health (Figure 22). In the intestines of children less than six months old, nitrate is reduced to nitrites. This readily combines with hemoglobin and impairs the body's oxygen carrying capability. The resulting disorder, infant methemoglobinemia, or "blue baby syndrome," can be fatal. Epidemiological studies also show a correlation between high nitrate levels and gastic and stomach cancers in humnas. Poultry and livestock can likewise be affected hy high levels of nitrate in water.

     Nitrate Treatment. Three methods can be used to reduce nitrate: 1) demineralization by distillation or reverse osmosis; 2) anion exchange; and, 3) blending. Of these systems, distillation and reverse osmosis are the most common and offer perhaps the most complete treatment for nitrates. Using bottled water or drilling a deepere well are also options to consider for nitrate-free water supplies. NOTE: Boiling nitrate bearing water will concentrate the nitrate and thus is not recommended.

     Becuae ion-exchange systems can treat large volumes of water, they are more appropriate for treatment of livestock water supplies. In the ion-exchange process, the anion resin in use takes up nitrate in exchage for chloride. In time, all the chloride will be exchanged for nitrate. The anion resin must then be recharged by backwashing with a brine solution (potassium or sodium chloride) (Figure 23). Since the backwash brine is high in nitrate it should be disposed of properly so as not to recontaminate the groundwater supply.

     Blending is the process of diluting the nitrate-comtaminated water with water from another source that has very low nitrate concentrations. Blending the two waters produces water that is low in nitrate concentration. Blended water is not safe for infants but is frequently used for livestock.

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