In most cases, the deep well water is perfectly safe to drink, but may have nuisance problems such as mineral tastes, hardness, or acidity. Most of these issues can be solved economically. Contaminants that pose an immediate or long-term health hazard are more difficult and expensive to remove. If your water is deemed unfit to drink by your local health department, you should work with them to find a workable strategy for getting potable water to the home. In all cases, it’s wise to get the advice of an experienced professional to help devise the most effective and economical strategy for treating the particular problem you are facing.
The most common types of treatments are described below. With any system, make sure the equipment is NFS-certified for the condition or contaminant being treated and is designed to meet the flow rates required in your household. Consider maintenance needs and costs, and filter costs and service life before selecting a system.
Household bleach can be used to treat a well and home piping contaminated with bacteria or other nuisance organisms that may cause disease or produce foul odors and tastes. This is used when a new well is built or repaired, new piping or plumbing added, floodwater has entered a well, or when iron or sulfur bacteria are causing odors or slime. The bleach is added to the well water, allowed to mix and settle, and later the well is flushed until clear of any traces of bleach. NOTE: If the bacteria are coming from a septic system, farming activities, or other ongoing sources, the problem must be solved or bacterial contamination will return.
Where ongoing chlorination is needed, consult with a water treatment expert about the feasibility and cost of automatic chlorination equipment called hypochlorinators.
These reduce the calcium and magnesium ions in the water that cause hardness. Most units work by binding the ions to sodium, reducing the water hardness, but increasing the levels of salt in the water. In areas with very hard water, the sodium levels may be high enough to pose a health risk for people on low-salt diets (a quart of very hard water, softened with sodium, will contain about 75 mg. of salt). The simplest solution is to bypass the water softener for one tap in the house used for drinking. Another more expensive alternative is to potassium chloride as the binding agent, although this can cause other health problems.
An expensive process called reverse osmosis (see below) can also be used to remove the sodium. A number of companies claim to offer “salt-free” water softeners. However, few if any are fully certified under NSF Standard 44 for water softeners. Make sure a unit has “system” certification, not just the component certifications required of all equipment used in potable water systems. Water softeners are designed to last for many years with minimal maintenance. The salt must be periodically replenished and inside of the equipment should be periodically inspected and any residue removed. If you are using a filter to remove iron and manganese, this should be plumbed before the water softener, as these minerals can foul the mineral elements in the softeners. See Hard Water Q&A.
Two types of equipment are used in homes to neutralize acidic water that is causing problems, such as blue stains of fixtures and corrosion. The most common system is a neutralizing filter. In the other a chemical feed pump or metering pump is used to inject neutralizing chemicals.
A neutralizing filter runs the water though a tank filled with calcium carbonate or ground limestone, and sometimes magnesium oxide or other minerals for high acidity. Look for a system with at least 1 cubic foot of filtration media. Chemicals are replenished once or twice a year by the homeowner or service company. Some “active” systems use a backwash system to keep the mineral bed clean and extend its service life. These work well, but use an extra 200 gallons of water a week for a typical family.
In a chemical feeder, a small pump is used to inject a solution of soda ash (similar to baking soda) and water directly into the well or into the plumbing before it enters the pressure tank. First a small amount of soda ash is mixed with water in a holding tank, and the injection pump is activated with the well pump kicks on. Feeder systems are sometimes used with high flow rates, or when the well water contains high levels of carbon dioxide or dissolved minerals. Soda ash injection does not increase water hardness. (A similar system can be used to lower the pH of highly alkaline water — pH above 8.5 — by injecting a weak acidic solution instead of an alkaline solution.) In addition to adding the soda ash, the pump, screens, and filters need periodic cleaning for the system to work properly.
There are a wide range of whole-house water filters on the market – some very effective, others pretty useless. A well-designed whole-house system can supply the pressures and flow rates required of a typical household and, depending on the filter element, can filter out a wide range of contaminants. Different types of filters are used for sediment, chemicals, and minerals such as iron and magnesium. As with all water purification equipment, pay attention to flow rates and pressure drops, maintenance requirements, and the cost and service life of filters. Also make sure the system, not just the components, is NSF-certified for the contaminants in question.
- Sediment filters mechanically strain out visible particles including clay, rust, sand, and other particles that contribute to turbidity. Water with large amounts of particles may need multiple stages. Some systems use reusable filters although most are disposable.
- Iron and Manganese. Iron leaves reddish brown stains on fixtures and clothing and manganese leaves similar brown-black stains. Both have a metallic taste. Both can be filtered out with special fine filter elements, often combined with chlorination or other chemical treatments prior to filtering. Iron removal can be complicated by the presence of iron bacteria, which often form a reddish-brown slime inside toilet tanks and similar places. It’s best to consult with professionals to analyze the specific problem and optimal solution.
- Chemicals.Many chemicals that effect smell, taste, and human health can be filtered out using very fine media. Many use activated carbon to remove contaminates such as chlorine, iron, VOCs, some heavy metals, and chemicals such as hydrogen sulfide (that causes rotten egg smell).Because chemical filters can clog easily, they are often installed in series with a sediment filter, which removes and large particles from the water before it reaches the finer filter element.
REVERSE OSMOSIS AND DISTILLATION
Because of their cost and relatively slow speed of treatment, these systems are generally installed at the sink or other point-of-use, rather than treating the whole-house water supply. RO wastes up to five gallons of water for each one treated, but can remove over 99% of harmful bacteria, and 95 to 99% of most chemicals including arsenic, nitrates, lead, and toxic metals. It is effective in removing salt and is widely used in desalination systems. Membranes typically need replacement every 2-5 years and can be costly. Also pre- and post-filters need replacement every 6 months to a year, depending on the system and usage levels.
Another option for producing pure water is distillation. This is slower then RO and uses a significant amount of electricity – up to 3 kWh to produce one quart of distilled water, making this prohibitively expensive to operate in areas with high electrical costs. Distillation provides the purest treated water, so is worth considering where water quality is severely compromised.