Home Water Treatment Systems
In a modern society, water is one of the things in life we often take for granted. When we turn on the tap, we expect water that is clean, safe and suitable for all household tasks. But in recent years, there has been a growing concern about contamination of our water supplies. We hear unsettling news accounts that make us question the safety of our water.
This publication provides a few guidelines for deciding whether you need to install a home water treatment system, and if so, how to select a system appropriate to your specific need.
|Identifying a Water Quality Problem|
No water is 100 percent pure. It contains contaminants from natural and man-made sources, such as minerals, gases, bacteria, metals and chemicals. Many of these contaminants are harmless. However, some impurities can adversely affect your health. Others damage equipment, stain laundry and fixtures and emit odors.
The first step in eliminating exposure to water-borne contaminants is to assess your situation. If your water comes from a public or municipal system, it is regularly tested for contaminants regulated by federal and state standards, such as microbial pathogens, radioactive elements and certain toxic chemicals. These are the contaminants that affect the safety of water and may cause health problems. Since public and municipal systems are regulated, a home water treatment system is seldom needed for health protection. Water quality problems such as hardness, corrosivity, foaming, staining or bad tastes, smell or color are undesirable. However, these factors do not necessarily make the water unhealthful.
If your water supply is a private well, you are personally responsible for testing and treating the water to avoid health risks. One of your major concerns should be microbial pathogens (bacteria, virus and parasites) in the water supply. This is especially important if your well is near a septic tank, or an area subject to animal wastes or nitrates. For further information, request a copy of Water Quality Problems - Health and Household and Testing for Water Quality from your Cooperative Extension Service agent.
If you are concerned about or dissatisfied with the quality of your water, have it tested by a state-certified laboratory. The analysis will identify the contaminants that are present and the extent of the problem. Determining which contaminants are present is essential in selecting a treatment system. Many types of water treatment systems are available. Each type of system is designed to treat specific water quality problems. No single water treatment system will treat all problems and all systems have limits.
|Treatment and Conditioning Systems|
Methods used to improve the quality of water are referred to as treatment or conditioning. What is the difference? Water treatment refers to systems that reduce harmful contaminants in the water, dealing with health and safety of the water. High levels of coliform, nitrates, arsenic, lead and pesticides are examples of harmful contaminants that must be treated before water is safe to drink.
Water conditioning refers to water problems that effect water taste, color, odor, hardness and corrosivity rather than health and safety. The presence of high levels of magnesium, calcium, iron, manganese and silt are common contaminants that require water conditioning. It is not uncommon to use both treatment and conditioning methods to improve water quality.
Here is a list of possible treatment and conditioning methods:
When shopping for in-home water treatment systems you will likely find systems categorized as point-of-entry or point-of-use treatment systems. Point-of-entry water treatment systems treat all of the water entering and being used in the home. Sedimentation filters, iron control treatment, water softener and a chlorination system used to control bacteria in the well are all considered point-of-entry treatment systems. Point-of-use water treatment systems, on the other hand, treats part of the water in the home water distribution system, usually at one faucet. The water is typically only used for drinking and cooking. Reverse osmosis, distillation and activated carbon filtration are examples of point-of-use water treatment systems.
Choosing an in-home water treatment device can be confusing and complicated if more than one water quality problem exists. Sometimes, several problems can be eliminated with one treatment. Activated carbon filters, for example, can remove taste, odor, chlorine, some pesticides and filter out particles. And occasionally, the treatment itself causes other problems. For example, ion exchange or reverse osmosis may make water more corrosive, requiring you to also use a neutralizing filter. Chlorination may form toxic organic compounds requiring you to install an activated carbon filter.
In many treatment cases two or more systems may be needed to satisfactorily treat the water. Disinfection by chlorination will kill bacteria. However, to remove the taste of chlorine, an activated charcoal filter is typically used. To remove particles of silt and sand, a mechanical filter should be added as part of the system.
Depending on your source of water, you may have to correct minor problems before you can address your major concern. The following guidelines for water treatment are based on the belief that it is practical and efficient to treat some water quality problems before others. For instance, only after turbidity, acidity, hardness and iron have been controlled will activated carbon filters, reverse osmosis units, or distillers operate efficiently.
Remember, these steps are a simplification of water treatment. When considering home water treatment, consult with water treatment professionals at a reputable and certified dealership to determine the best treatment approach for your problem.
|Water Treatment Steps:|
Drinking water should be free of coliform bacteria. The EPA drinking water standards indicate that water should contain less than one coliform organism in 100 milliliters. If your coliform test was reported as contaminated, take these steps:
There are a number of ways of disinfecting water but remember, treatment of a water supply is a safety factor, not a corrective measure. Don't install a permanent means of disinfection unless you are sure the contamination originates from the groundwater and that it is not a temporary condition.
The use of chlorine is the oldest and most common disinfection method for private water supplies. Chlorine is inexpensive and readily available, reliable, easy to use and monitor, and effective against most pathogenic bacteria, virus and cyst organisms. It also kills non-pathogenic iron, manganese and sulfur bacteria.
Chlorine is also a strong oxidizing agent which causes a problem mineral such as soluble iron and manganese to change to an insoluble precipitate so it can be filtered from the water.
For use in the home, chlorine is readily available as sodium hypochlorite commonly known as household bleach. This product contains 5 percent available chlorine. Chlorine is also available as calcium hypochlorite, which is sold in the form of dry pellets. In this form it has about 70 percent available chlorine.
Chlorination may be done in many ways. Chlorine may be used continuously in the dry or liquid form that is dropped or injected into the well water using a chemical feed pump. For periodic or shock water treatment, chlorine can also be poured in or fed in solution using a hose.
Shock chlorination is recommended whenever a well is new, repaired or found to be contaminated. It is essential following a flood or entrance of surface water into the well. It is also done to control nuisance problems such as iron bacteria.
Before shock treatment, warn everyone not to use the water. Children and elderly persons in the household may require special care. Strongly chlorinated water (less than 500 ppm chlorine) is not harmful to livestock but they will refuse to drink unless very thirsty. Make provisions for drinking water before doing a shock chlorination treatment, particularly if the solution is to be left in the system overnight.
If bacteriological problems persist following shock chlorination, a continuous chlorination system may be required.
|Emergency Disinfection Measures|
During an emergency and to disinfect small quantities of water for drinking, cooking, and brushing teeth, temporary methods are sometimes necessary. These methods are not recommended for general or regular use.
Boiling - First clear the water by letting it settle and filter through a clean cloth. Boil the water vigorously for one full minute; boiling will kill all bacteria. Overboiling, however, can concentrate chemical impurities such as nitrates. Store the boiled water in sterilized containers if possible. The boiled water will have a "flat" taste which you can eliminate by aeration.
Chlorine Bleach - Add 10 drops of chlorine bleach to one quart of water, mix the treated water thoroughly and let it stand for 30 minutes. If the water does not have a slight chlorine odor, repeat the dosage and allow it to stand for another 15 minutes. If the water tastes too strongly of chlorine, expose it to the air for a few hours or pour it from one container to another several times.
Granular Calcium Hypochlorite - Add a heaping teaspoon of calcium hypochlorite to 2 gallons of water. Use one pint of this chlorine solution in 200 gallons of water.
Chlorine Tablets (Halazone) - Add 1 tablet per quart of water. Be sure to read the manufacturer's directions carefully.
Iodine Tablets - Add 1 tablet per quart of water - check label for quantity to use.
Continuous disinfection requires equipment to add chlorine to all water drawn from the source. The chlorine must be thoroughly mixed with the water and have sufficient contact time to kill all disease-causing and nuisance organisms. The time required for disinfection depends on the concentration of chlorine, temperature and pH of the water, the amount of organic matter in the water, and the discharge rate of the pump. Disinfection for most water-borne disease-causing organisms occurs after 20 minutes of contact time when the pH is between 6 or 8 and the free available chlorine residual is in the range of .2 to .4 parts per million.
Research findings indicate that suspected carcinogenic compounds, called trihalomethanes, can actually be formed during chlorine disinfection when organic substances are present. To remedy this, activated carbon filtration or reverse osmosis units should become a part of all up-to-date home chlorination systems. To remove chlorine taste, use an activated carbon filter after the contact tank and just before the point of use faucet. Continuous chlorinators range in price from $500 to $1300.
|Ultraviolet Light Disinfection|
Ultraviolet light is a relatively new method of disinfecting private water systems. Ultraviolet radiation adds nothing to the water and does not produce any taste or odor. The UV light is produced by a mercury vapor lamp which produces a disinfecting dose rated in microwatt-seconds per square centimeter (MWs/cm2). Values of 20,000 MWs/cm2 will kill most types of pathogenic bacteria. However, viruses are more resistant and variable and may need up to 45,000 MWs/cm2.
An ultraviolet water treatment device is quite simple. The most common design consists of a stainless cylindrical chamber with a cylindrical mercury arc lamp located in it. Lamps vary in length from 12 to 48 inches and thus vary in energy output. Water enters one end of the chamber, flows through the chamber around the lamp and exits the other end within a few seconds.
To be effective as a disinfection treatment, ultraviolet radiation must pass through every particle of water. The thinner the water film and the slower the water flow, the more effective the system will be. Also, the water cannot have any turbidity, suspended soil particles, or organic matter. As a consequence, ultraviolet light treatment should only be attempted on clear water. A prefilter is recommended on ultraviolet systems as is periodic inspection and lamp cleaning. As a result, without regular inspection and maintenance, water treated by UV cannot be guaranteed to be bacteria free. In fact, one major distributor of the system adds this disclaimer of liability to its literature: "This product is designed for use only on water known to be of acceptable bacterial quality. Its intended use is as a safety device on private and non-municipal potable supplies already identified as safe to drink. If you think your water may be unsafe, please contact your local public health agency."
The cost will be at least $900 for a 47,000 microwatt-second household UV treatment system with a flow rate of 8 gallons per minute.
Distillation provides another water disinfection option as a point-of-use system. Distillers are also used to reduce nitrates, remove dissolved salts like chlorides, sulfates and carbonates of sodium, potassium and magnesium, organic matter and other soluble and suspended materials. Distillation units boil water, making steam that is condensed and collected as purified water.
Home distillers vary in design. However, the countertop single-batch version is most common. These distillers cost $250 to $1,200. All home electric distillers use 100-120 volt a.c. current. The water output of a home distiller ranges from 3 to 12 gallons per day. The power consumption of these systems varies from 3 to 5 kilowatt hours of electricity per gallon of distilled water produced. Thus the electric cost of distilled water can be high.
There are drawbacks to distillation. The most serious is that liquids with organic molecules whose boiling point is less than that of water will be carried with vapor into the condensate chamber and distillate reservoir. Chloroform, phenol and trichloroethylene have been found in the finished water.
Because distilled water is mineral free, it tends to taste flat and is hard on metals. Draw water directly from the distiller and not through any metal piping. Distiller tanks, if not properly used and maintained, can also become notorious breeders of bacteria because of the presence of warm water. To remove bacteria and concentrated salts, disinfect and clean regularly.
Filtration represents a broad category of treatment systems used to remove particles, taste, odor, some organics and minerals, and some bacteria from the water. Filtration systems fall into several categories:
In many cases, these filtration systems are an integral component of other water treatment systems. To remain effective, all filtration systems must be regularly inspected and maintained.
Mechanical or sedimentation filters simply retain debris as water passes through the filter unit. Mechanical filters are most effective for removing particles such as sand, silt, ferric iron, algae and some bacteria. Their effectiveness will depend on the particle size and the exit clearance of the filter.
|Activated Carbon Filtration|
Activated carbon filtration is a common treatment to remove offensive tastes and odor, color, chlorine and volatile organic chemicals, pesticides and trihalomethanes (a group of suspected carcinogens). Activated carbon will not remove bacteria, dissolved metals such as iron, lead, manganese and copper, or chlorides, nitrates and fluorides.
Activated carbon filters, usually made up of granulated, powdered or block carbon, act like a sponge with a large surface area to absorb contaminants in the water. Activated carbon, made from coal and nutshells, has a tremendous surface area - as much as 125 acres per pound of carbon. The efficiency of an activated carbon filter is dependent on the amount of carbon in it and the flowrate of water through the filter. The typical carbon filter is about 10 inches high and 3 inches in diameter - enough charcoal to treat about 1,000 gallons of water.
Home-use activated carbon filters are most commonly sold as faucet-mounted, stationary and line bypass systems. The stationary system is connected directly to the cold water faucet. The line bypass system has a separate faucet, but is tapped into the cold water pipe for its water supply. These systems are typically installed under the sink and can be purchased for $50 to $375. Pour-through carbon filters are also on the market. However, due to the small amount of carbon and minimal water contact time with the carbon, this system has limited effectiveness. This is also true of the faucet-mounted carbon filter costing about $25. A carbon unit for radon removal resembles a water softener tank and costs about $1,500 plus installation. Without periodic replacement, carbon filters may provide a breeding ground for bacteria. To assure maximum effectiveness, replace any carbon filter frequently, following the manufacturer's recommendations.
|Oxidizing filters are used mainly to remove iron, manganese and hydrogen sulfide. Manganese greensand is a common chemically reactive medium designed to remove iron and manganese that is in solution. The greensand will also act as a filter and catch iron and manganese precipitates that have been oxidized. The unit works by providing oxygen to the iron and manganese from the greensand bed. As a result, these minerals change from their soluble to insoluble form. The precipitated minerals become trapped as rust particles within the greensand filter bed. To remain effective, manganese greensand filters must be periodically backwashed to thoroughly remove iron precipitate, and regenerated when the oxygen is depleted.|
|Neutralizing filters are typically used for pH modification, or treating acidic water. A neutralizing filter is normally a pressure filter tank filled with limestone chips. As the water passes through the filter bed, calcium carbonate is dissolved into the water and the water pH is increased, reducing its acidity.|
|Reverse Osmosis Filtration|
Reverse Osmosis or "R.O." filtration systems for home water treatment are relatively new, although the process has been used extensively for industrial processes. Reverse osmosis treatment decreases dissolved minerals in the water. It successfully treats water with high salt content, and dissolved minerals such as nitrate, sulfate, calcium, magnesium, potassium, manganese, aluminum, fluoride, silica, boron and bicarbonate. R.O. is also effective with some taste, color and odor-producing chemicals, certain organic contaminants, and specific pesticides.
Although the R.O. membrane is capable of rejecting virtually all microorganisms, it can develop pinholes or tears that allow bacteria or other microorganisms to pass into the treated water. So R.O. is recommended only for bacteriologically safe water.
Household R.O. systems typically treat 3 to 5 gallons of water per day. However, some can treat between 1 to 9 gallons. R.O. systems range in cost between $100 and $850. The wide range reflects differences in capacity and design. The simplest home R.O. system consists of a membrane filter connected to the faucet spout. Most popular is a membrane, a storage container for the treated water, and a flow regulator for the reject water. The pressure for R.O. is usually supplied by the line pressure of the water system in the home. A sediment prefilter and activated carbon prefilter or postfilter might be included. The prefilter removes sand, silt and sediments, while the activated carbon removes the organic materials and dissolved gases not treated by the R.O. membrane. Water softeners are used in advance of the R.O. system when household water is excessively hard.
|Water Softening or Ion Exchange|
Water softening to condition hard water is perhaps the most familiar water conditioning system known to consumers. Hard water is caused by calcium and magnesium that are dissolved in the water. This causes scale to form in hot water pipes and water heaters. It interferes with the cleaning action of soaps and detergents, and forms a film on skin, clothing and fixtures. Hardness is measured either as milligrams per liter or parts per million. However, it is normally expressed in grains of hardness per gallon of water. The table lists the relative hardness of water expressed in both forms. Water Hardness Grains per Gallon Parts per Million (ppm) Soft 0 to 3 0 to 60 Moderate 3 to 7 60 to 120 Hard 7 to 10 120 to 180 Very Hard more than 10 more than 180
Softeners also will remove small amounts of iron and manganese if they are in a soluble or ferrous form.
The most common way to soften water is the cation-exchange water softener. A synthetic resin with a strong attraction for calcium, magnesium and other positively charged metal atoms called "cations" is saturated with sodium from a salt solution. As water passes through the resin, the sodium exchanges with the calcium and magnesium. Eventually, so much hardness collects on the resin that the unit can no longer soften the water and recharging is necessary. Then, the softening material is backwashed with a brine solution to replace the sodium and enable the ion exchange process to continue.
The major disadvantage of water softeners is that they remove beneficial calcium and magnesium and substitute sodium. People who are on a restricted sodium diet may be advised not to drink softened water. To overcome the problem, soften only the hot water tank lines, leaving the major cold water line for drinking unsoftened water. Softened water is more corrosive than unsoftened water, and the waste brine may be a disposal problem. Softening systems range from $650 to $2,100.
|Renting Equipment and Using Bottled Water|
In certain situations, purchasing water treatment equipment is not the best alternative. If the water has been contaminated by a spill, and permanent treatment is not required, renting equipment or buying bottled water are viable solutions.
Renting is a practical way to become familiar with the device prior to purchase. Renting allows you to determine maintenance requirements, costs and the effectiveness of the treatment system. Also, if you are renting your residence but you are not pleased with the water quality, equipment rental is reasonable. A rental agreement should clearly specify in writing the responsibility for maintenance, as well as any application of monthly rent to an eventual purchase. Insurance costs and periodic testing are other stipulations that need to be made.
Enforcement of chemical and microbiological standards for bottled water varies between states. Generally, standards for bottled water are no more stringent than those for public water systems. It is probably not cost-effective to purchase bottled water for health reasons when the normal supply is a municipal system, unless there is a health hazard within the home distribution system (such as lead pipes). There is no maintenance requirement with bottled water, nor any mechanical apparatus to operate, which appeals to some people.
Cost is a major determining factor in deciding to purchase or rent water treatment equipment, or to buy bottled water. The situation determines which may be less costly. Watch for hidden expenses such as separate installation fees or monthly maintenance fees. Additionally, the disposal of waste materials, such as reject water from reverse osmosis systems, spent cartridges from activated carbon units, and used filters, can add to the cost of water treatment and should be figured into the purchase or rental price.
|Sales Scams and Misleading Promotions|
Until recently, the point-of-use water treatment industry focused on improving the aesthetic quality of drinking water. The industry has lately been thrust into the forefront of treatment of contaminated drinking waters that pose a serious health hazard. The response has been an explosion of companies and products promising to render the consumer's drinking water safe and contaminant free.
Although many sellers of water treatment units are legitimate, some are unscrupulous. As part of their sales pitches, some dealers may falsely claim that the drinking water in your area contains a harmful level of chemical contaminants, such as chlorine or lead. Although certain communities may experience various levels of water contamination, your community may not. Therefore, you may wish to verify the dealer's claims about your drinking water with your local or state department of health before purchasing any product.
Some dealers also may claim that certain government agencies require or recommend widespread use of water filters in homes or restaurants, or that the government approves a particular unit. This is not true. If you see an EPA registration number on a product label, it merely means that the manufacturer has registered its product with the EPA. A registration number does not mean that the EPA has tested or approved the product or substantiated the manufacturer's claims.
Some sellers advertise in the local media, offering a free in-home test of your drinking water if you call. Although in-home testing may be a legitimate sales tool, some promoters use unsophisticated tests to convince you of the need to purchase their product. For example, they may test only for acidity/alkalinity, water hardness, iron, manganese and color. None of these indicate the presence of harmful contaminants. Others may test only for chlorine, which, although present in your drinking water, may not be at harmful levels. If you suspect your water is contaminated, review all sources of information, consult a qualified water quality contractor and/or have your water tested by an independent laboratory before investing in a water treatment unit.
Be aware that water filters sometimes are sold as part of prize promotions, which may not be legitimate. Some companies send out postcards saying that you have been selected to receive a prize, and, to receive further details, instruct you to call a telephone number, usually toll-free. If you call, you may discover that you must purchase a water treatment unit to be eligible for a prize, which may be of little or no value. Sometimes sellers will request your credit card number, saying they need to verify your eligibility for a prize or to bill your account. Be cautious about giving your credit card number over the telephone to someone you do not know. Many consumers who have purchased water treatment units from telephone sales have found later that the units do not remove contaminants from the water and that they cannot cancel their orders or return the products to obtain refunds.
If you are considering purchasing a water treatment device from a manufacturer unfamiliar to you, contact your state consumer affairs office to learn if it has received any complaints against the company. In addition, you can contact the National Sanitation Foundation, which operates a voluntary certification program for water treatment products. Although this organization cannot rate or recommend a particular brand of water treatment unit, it may be able to provide you with useful information about various water treatment devices and technologies. Address: The National Sanitation Foundation, 3475 Plymouth Road, P.O. Box 1468, Ann Arbor, Michigan 48106, (313) 769-8010. Problems with misrepresentations or fraudulent claims can be addressed to the Federal Trade Commission, 6th and Pennsylvania Avenue, N.W., Washington, DC 20580, Phone: (202) 326-2222, or to the Attorney General of your state.
|Questions to Ask When Purchasing Water Treatment Equipment|
Here are questions the consumer should ask a water treatment professional to determine the system needed; background information follows many of the questions. These questions should be used as guidelines. The extent to which the manufacturer or distributor is willing to provide answers can assist the consumer in making an informed choice.
1. What exactly does the analysis of the water (by the treatment professional) indicate? Are health hazards indicated? Should additional tests be made?
Many water treatment companies include in their services free in-home testing of the water, but not all contaminants can be detected this way. For example, organics, which have been associated with serious health problems, must be analyzed in a laboratory with sophisticated equipment. The consumer must be wary of home analysis claiming to determine more than basic water quality constituents (pH, iron, and sulphur).
2. How long has the company been in business, and are there referrals you can contact?
3. Have the product and the manufacturer been rated by the National Sanitation Foundation (NSF) or other third party organization? Was product tested for the contaminant(s) in question over the advertised life of the treatment device (with more than one gallon of water), under normal household conditions (tap water, actual flow rates, and pressures)?
The NSF, whose function is similar to Underwriter's Laboratory, sets performance standards for water treatment devices. Because companies can make unsubstantiated statements regarding product effectiveness, the consumer must evaluate test results of the device to determine if claims are realistic.
4. Does the water quality problem require the whole-house treatment or will a single-tap device be adequate?
Less than 1 percent of tap water is used for drinking and cooking. Some contaminants are as hazardous when inhaled or absorbed through the skin as when swallowed. Treatment of all water used in the household may be required. Reverse osmosis and distillation units are connected to a single tap. Activated carbon devices can be installed on a single tap or where water enters the house. The device selected depends on the type of contaminant in question.
5. Will the unit produce enough treated water daily to accommodate household use? If a filter or membrane is involved, how often will it need to be changed? How does the consumer know when to change filters?
The consumer must be certain enough treated water will be produced for everyday use. The maximum flow rate should be sufficient for the peak home-use rate. Activated carbon units, reverse osmosis units and iron filters need routine maintenance. You should be fully informed of maintenance requirements.
6. What is the total cost to buy and maintain the device? Will the company selling the device also install and service it? Is there a fee for labor? Can the consumer perform maintenance tasks or must a professional be involved? Will the unit substantially increase electrical use in the home?
The consumer must watch for hidden costs, e.g., separate installation fees, monthly maintenance fees or equipment rental fees. Additionally, the disposal of waste materials (reject water, spent cartridges from activated carbon units, and used filters) can add to the cost of water treatment and should be figured into the purchase price.
7. Is there an alarm or indicator light on the device to alert the consumer to a malfunction? Does the manufacturer include in the purchase price a retesting of the water after a month or two?
Many units have back-up systems or shut-off functions to prevent consumption of untreated water. Testing the water a month after the device is installed assures you the unit is accomplishing the intended treatment.
8. What is the expected lifetime of the product? What is the length of the warranty period, and what does the warranty cover?
The warranty may cover only certain parts of a device, so you should be aware of the warranty conditions.
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