What consumers do, if anything, about water quality is usually an indefinable combination of various factors and almost always includes understanding, personal preference and budget. Even some people who live in established water-problem areas do not want to know what is in their water. For others who have been drinking well water for years (or even generations), they perceive no correlation between any adverse health conditions and water.

If you are on a municipal or community water system, you have some comfort that your water quality is being monitored to ensure EPA compliance. Most complaints about public-system water have to do with residual taste ("chlorine taste") imparted by chemical agents used to eliminate microorganisms, scale (calcium and magnesium "hardness" buildup on fixtures, in water heaters, and spotting on dishes), and concern about what potentially harmful contaminants might be present. Remedies for taste improvement include faucet and pitcher filters and bottled water for drinking and cooking. Hardness can be treated with conventional ion-exchange water softeners and salt-free systems.

The latest nanotechnology in salt-free systems uses media certified by National Sanitation Foundation International (NSF) and requires no electricity, no drain and no wasteful backwashing. Under-sink, reverse-osmosis systems provide the highest-quality water for drinking and cooking. Reverse-osmosis water can be remineralized to enhance its taste. Insist on NSF certification of contamination reduction (see the system's performance data sheet) and be wary of certification only on individual system parts.

The decision tree for well water can be much more complex. The first concern should be bacterial contamination, which is commonly treated by "shocking" the well with chlorine bleach. If shocking is not effective, the next step is running conditioned water through ultraviolet light. Along with bacteria testing, the EPA recommends initially running a complete laboratory test suite on your well water to establish a baseline for monitoring any future changes in water quality.

Hardness is a common complaint about well water. Iron and manganese staining are common complaints in well water and treatment methods are dictated by chemical valence. Iron removal is often not a simple, generic solution.

If you even think that your well water may need treatment (talk to your neighbors!), consider ordering a laboratory test. On-site testing is just not reliable for system design. Nitrate and arsenic are two common invisible, odorless contaminants that can be detected and quantified through lab tests and can be treated by specialized systems. Local nitrate contamination is commonly attributable to septic-system leakage. Arsenic is naturally occurring in this area and is more difficult to treat because it commonly exists in two chemical valences. In certain areas, testing for radionuclides in well water is recommended.

Even after complete suites of lab tests are collected and interpreted, some well water quality is so good that deciding to do nothing about it is a good decision. It's your water, and you get to choose what action, if any, to take about water testing and treatment.

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 7/1/2007 in Santa Fe New Mexican's Real Estate Guide p124