New Hampshire Reduces Arsenic Standard by Half 

New Arsenic Standard

On July 12, 2019, Governor Chris Sununu signed a bill reducing the state drinking water standard, or maximum contaminant level (MCL) for arsenic from 10 to 5 parts per billion, which is half of the federal default standard.  According to New Hampshire Department of Environmental Services (NHDES) officials, the new standard will apply to public water systems and environmental monitoring sites.  Private water supplies are not regulated in New Hampshire. 

Arsenic is naturally occurring, is commonly found in New Hampshire’s groundwater, and has been linked to an increased prevalence of bladder and other cancers as well as developmental effects in children.  According to NHDES officials, new rules are required for the new, reduced arsenic drinking water standard, which are anticipated to become effective in July 2021.

For more information, use the following link to view the NHDES’ December 31, 2018, Review of the Drinking Water Maximum Contaminant Level (MCL) and Ambient Groundwater Quality Standard (AGQS) for Arsenic.

August 13, 2019


arsenic, water supply George C. Holt, PG
Principal Hydrogeologist

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