New Hampshire Public Water Suppliers have two years to prepare to comply with the newly adopted arsenic maximum contaminant level (MCL) of 5 micrograms per liter (ug/L) or parts per billion (ppb). The current federal MCL established by the United States Environmental Protection Agency (US EPA) for arsenic is 10 ppb.
Arsenic is a naturally occurring contaminant in drinking water originating from rock and soil deposits containing arsenic. The presence of arsenic can also result from human activities such as use of pesticides or glass and electronic production wastes. It is generally understood that most of the arsenic occurring in New England drinking water wells is associated with naturally occurring bedrock deposits.
Drinking water with elevated levels of arsenic increases the risk for certain types of cancer including bladder, lung and skin cancers, increase the risk of cardiovascular disease and increase the risk of birth defects and reduced IQ in children.
Why did NH decide to lower the MCL?
The NH Department of Environmental Services (NHDES) sites the demonstrated risk of arsenic in drinking water at levels below the US EPA MCL of 10 ppb and proven ability of water treatment technologies to reliably achieve removal to levels of 5 ppb or less in finished water. The full report on the NHDES recommendation for lower arsenic level can be viewed at the following site:
For more information on the NHDES drinking water standards visit:
How does this impact public water suppliers outside of NH?
Regulators keep track of new regulations implemented by other states. Arsenic deposits are found around the country. The United States Geological Survey (USGS) has published studies identifying the areas with greater prevalence of water supply wells with elevated levels of arsenic. In particular, the USGS report entitled “Quality of Water from Crystalline Rock Aquifers in New England, New Jersey and New York, 1995 – 2007” updated March 2018, presents data identifying wells with arsenic (1) greater than or equal to 10 ppb, (2) in the range of 5 ppb to less than 10 ppb, and (3) less than 5 ppb. Refer to the below figure and the link to the USGS report for more details. While there are a greater number of wells that have been identified with elevated arsenic in NH, there are a number of impacted wells in Maine and Massachusetts and keep in mind that the sample study did not include data from all public water supply wells. However, the data and graphic is useful in providing a visual of where impacted wells may be located. https://pubs.usgs.gov/sir/2012/5156/pdf/sir2012-5156_ayotte_508.pdf
Should you have questions regarding arsenic in drinking water or methods of treatment, please contact ResilientCE at 508-726-2458 or admin@resilientce.com.
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