Owners of private wells are responsible for monitoring their own water quality. Even though testing is not required, the Environmental Protection Agency recommends that private wells be tested prior to domestic use to detect any contaminants. This initial testing enables the owner to establish a baseline for tracking and comparing any future changes in water chemistry. The EPA also recommends that owners test wells annually for coliform bacteria, nitrates and other constituents that may be of concern in localized areas.

The most reliable way to find out what is in your well water is to commission a comprehensive test by an EPA-approved laboratory. Testing is particularly important if you live in an area of known risk for certain contaminants. If you are going to invest in well testing, use a company with expertise in collecting water samples, interpreting test results and explaining treatment implications (if any).

EPA standards for regulated wells serve as useful guidelines for evaluating the quality of water from unregulated private wells. Some common contaminants have only aesthetic effects (such as taste, odor or color) in drinking water and others are annoying (copper, iron and manganese staining) and may permanently discolor plumbing fixtures. High hardness levels may result in clogged plumbing and impaired operation of electrical devices that use water. In EPA-regulated wells, these effects are included under non-enforceable secondary standards.

Some contaminants with possible implications for human health may be invisible and have no characteristic odor. In EPA-regulated wells, the levels of these contaminants (including microorganisms, disinfectants, disinfectant byproducts, inorganic and organic chemicals, and radionuclides) are governed by legally enforceable primary standards and should be properly evaluated if contaminant levels exceed the EPA's maximum contamination level (MCL).

In areas where multiple contaminants are known to be present, laboratory testing can be costly. There are some (limited) options for obtaining reliable, free water testing by certified laboratories. The New Mexico Department of Health is conducting a statewide study of arsenic and metals in drinking water and urine. The initial phase of testing has already been completed in Northern New Mexico.

The New Mexico Environment Department, under its Liquid Waste (Septic Tank) Program, provides free and confidential testing of private domestic wells for fluoride, iron, and nitrate. The NMED also conducts periodic "water fairs" at which residents can get their well water tested without charge.

Because water quality in Northern New Mexico is changing as a result of drought conditions and development, consider testing the water (or acquiring a copy of recent laboratory test results) before you buy a house that is dependent on water supply from a private well. It is also suggested that you gather information about nearby wells if you are buying undeveloped land and anticipate drilling a water well.

The confidentiality of your test results is critical because the diagnosis of problem water, if not properly disclosed, can adversely affect real-estate transactions.

Stephen Wiman has a background in earth science (Ph.D. in geology) and is the owner of Good Water Company in Santa Fe. He may be reached at 505-471-9036 and skwiman@goodwatercompany.com.

Originally published 5/6/2007 in Santa Fe New Mexican's Real Estate Guide p103