NHDES Recommends Lower Arsenic Level

Concord, NH – On December 31, 2018, the New Hampshire Department of Environmental Services (NHDES) submitted a report to the Legislature recommending a more protective limit for the amount of arsenic in drinking water provided by public water systems regulated by the department. NHDES proposes a new limit of 5 parts per billion (ppb). NHDES has been enforcing a limit of 10 ppb, established by the U.S. Environmental Protection Agency (EPA) since 2006. Before 2006 the limit was 50 ppb.

Arsenic is an element that occurs naturally in various rock formations, including some that are quite common in New Hampshire. More than one third of the community water systems in the state have a measureable amount of arsenic in their water. Consuming water with arsenic over a long period of time increases the risk of bladder, lung, and skin cancer as well as cardiovascular disease. Arsenic in drinking water has also been linked to increased risk of adverse birth outcomes and reduced IQ in children.

By law, lowering the drinking water standard known as a maximum contaminant level (MCL) will also lower the ambient groundwater quality standard (AGQS), which is used to require remedial action and the provision of alternative drinking water at a contaminated site and also sets limits under which treated and untreated wastewater may be discharged to groundwater.

In 2018 the Legislature directed NHDES to review the regulatory limits for arsenic in drinking water and groundwater and to document their findings in a report by January 1, 2019. NHDES intends to work in consultation with the Legislature to lower the drinking water and groundwater standards for arsenic in 2019. In making its proposal, NHDES considered the prevalence of arsenic in New Hampshire water supplies, the adverse health impacts that could be avoided by lowering the limit, the cost of water treatment to remove arsenic, and other factors all of which are explained in the report.

For more information, please contact Paul Susca, NHDES, at (603) 271-7061.