Bow study finds chloride, acidity in Brown Hill Road wells

Monitor staff
Saturday, May 21, 2016

High levels of chloride and low pH have been traced in wells in the area of Brown Hill Road in Bow, according to a study by the town’s Drinking Water Protection Committee.

Residents on Brown Hill Road have complained of corrosion from salt contaminating their wells since the 1990s, the report says. In July 2013, residents brought the issue back to the select board, which then assigned it to the Drinking Water Protection Committee.

The committee received permission from 79 homeowners in the neighborhood to test their wells between July and September 2014, and results were returned in December.

The study found wells installed before 1985 to have higher levels of chloride and lower pH (higher acidity) compared with newer wells, “likely because older wells were not sealed into bedrock, and therefore are more susceptible to recharge from acid rain and surface drainage including salt contamination,” according to the report.  

Wells installed after 1985 were required to have at least 10 feet of casing sealed into the bedrock.

The reports states homeowners with newer wells did not express concern of corrosion, but the study did find “naturally occurring contaminants arsenic and uranium. The study found 30 percent of the samples had arsenic levels above drinking water standard, and 18 percent had uranium levels above the standard.

The report concluded current chloride levels were similar and slightly lower than levels tested in the 1990s, “suggesting that road salt loading has not increased the concentrations found in groundwater.” Chloride contamination in wells can come from road salt drainage and softener from home water treatment systems.

The committee will host a public information session on June 8 at 7 p.m. at the old town hall, 91 Center Road, Bow. The full study can be found on bow-nh.com and questions can be directed to the Drinking Water Committee at bowdrinkingwater@gmail.com.