While municipal water supplies are required by law to be tested, private wells are not, and not unexpectedly, few are sampled routinely for any of the dozens of contaminants from animal feces to farm pesticides that can make water drawn from them unhealthy. However, that does not make up for a past history of dumping contaminants into the ground. In early 1997, the region's largest underground water supply, the Barnes Aquifer, was contaminated by an industrial solvent, trichloroethylene. In a portion of West Holyoke and Southampton, more than a dozen households with private wells had to use bottled water. He said that monitoring of the plume of contamination over the last two years has shown it is not spreading to the rest of the aquifer and has not increased in concentration.
New projects have to use more environmentally sound practices.
The contamination was eventually traced to a septic tank at a private home, where it was estimated five to 10 gallons of the solvent dumped in the tank had caused all the trouble. Contamination can enter drinking water elsewhere than at the source. Sometimes pipes can pollute water. Lead pipes in older homes can add unhealthy levels of lead to water, a pollutant that can affect the development of children. That has been a problem over the years in Springfield and other older urban areas.