High Levels of Arsenic, Uranium Detected in Connecticut Drinking Wells

A U.S. Geological Survey study has found some private water wells in Connecticut have high levels of naturally occurring arsenic and uranium in them, and residents are being urged to get their water tested.

Around 23 percent of Connecticut residents have private water wells for their water supply, the USGS said.

In the study, posted in November 2020, thousands of water samples from more than 2,000 private drinking water wells in the state between 2013 and 2018 were analyzed. 2,433 samples were studied for arsenic and 2,191 for uranium.

The most recent data has shown that around 3.9 percent of private water wells contained water with arsenic concentrations higher than 10 micrograms per liter—the maximum level for public drinking water standards granted by the Environmental Protection Agency.

In addition, around 4.7 percent of wells contained uranium concentrations higher than the EPA's drinking water standards.

Arsenic can enter the water supply either from natural deposits in the Earth, but it can also be dumped by industrial outlets, the Centers for Disease Control and Prevention states. In private water wells, it may come from previous fertilizer use or industrial waste.

Arsenic has been related to increased cancer risk, low birth weight, decreased child intellectual development, immune system suppression and other health effects. Excessive uranium exposure can also be harmful and has been linked with kidney disease.

Ryan Tetreault, private well program supervisor at the Connecticut Department of Public Health—which cooperated with the study—said in a statement: "Even though we know there are areas across our state that have higher concentrations than others, any private well in Connecticut has the potential to have elevated arsenic or uranium. Private well owners should have their well water tested at least once for these contaminants."

A listing of environmental labs approved to test drinking water can be found here.

The department recommends that anyone using a water well with arsenic concentrations above federal and state levels should either swap to another water source or install a treatment system.

Wells containing uranium concentrations higher than EPA standards should also be treated, the USGS said.

The USGS study follows on from another, similar one carried out in 2017 which also identified areas where there were high levels of arsenic and uranium in Connecticut water wells.

The 2017 study found seven percent of water samples from 674 private wells in the state contained arsenic or uranium concentrations that were higher than the EPA's maximum contaminant levels (MCL) for drinking water supplies. The MCL for 10 micrograms per liter for arsenic and 30 micrograms per liter for uranium.

The newest study included additional samples and focussed on previously underrepresented areas.

Eliza Gross, USGS physical scientist and lead author of the study, said: "The previous USGS study published in 2017 identified some areas where there were high contaminant levels, and we now have a more complete statewide assessment."

Water in glass
A stock image shows water being poured into a glass. The USGS said an estimated 23 percent of Connecticut residents use private wells for their water supply. Pinkomelet/iStock