Disinfection destroys bacteria and other microorganisms in drinking water. However, it is not a long-term substitute for a safe water supply. If living organisms have contaminated your private well or water supply, proper disinfection kills them. However, it won't reduce nitrates or eliminate other contamination problems.

Water can be disinfected with heat, chemicals, or light. Boiling water kills bacteria and parasites like giardia and cryptosporidium. The Center for Disease Control (CDC) and the Minnesota Department of Health (MDH) recommend that you bring the water to a rolling boil and boil it for at least one minute. Cool and do not contaminate it with dirty utensils, hands or containers after boiling. Boiling water will concentrate any nitrate that is in the water. Therefore, don't boil if there's nitrate in the water.

Water can also be disinfected with chlorine, bromine, iodine, or ozone. Chlorine also oxidizes iron and manganese so they can be filtered out. Yet, high concentrations of chlorine give water a bad taste. Chlorine may combine with organic contaminants to form cancer-causing compounds. Ozone may be used to disinfect public water supplies, but is rarely used for private supplies.

Chlorine is used most often to disinfect private wells. A well may be contaminated when flooded or when the watertight casing is no longer intact. It may be contaminated when opened for maintenance or repair. Homeowners can chlorinate wells themselves or hire professionals. If you hire professionals, make sure they are licensed contractors.

If you disinfect your well, calculate how much chlorine you need. It is important to disinfect the entire household plumbing system. Chlorine must stay in piping long enough to kill all living organisms. Extension has a publication that helps calculate how much chlorine to add to your system. It explains how to disinfect your well.

Ultraviolet light can disinfect water, although it has limitations. For instance, the water must be filtered and be free of iron or other compounds. They could interfere with the ultraviolet lights' ability to penetrate cell walls to kill living organisms. Some counter-top water treatment systems use ultraviolet light.

Continuing disinfection is no substitute for a permanent safe water supply. It helps reduce nuisance bacteria and odors. It can make water safe until a sanitary supply is secured. If your well is contaminated, boil water, carry water from a safe supply or buy bottled water until the problem is corrected.

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