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Lower arsenic limits for new wells in Snohomish County

Board of Health aligns local requirements with federal standards

SNOHOMISH COUNTY --- By unanimous vote at their July 8 meeting, Snohomish County’s local Board of Health lowered the acceptable limit of arsenic in private drinking water wells. The old maximum level was 50 parts per billion, and the new level is 10 parts per billion. New research indicates that long-term consumption of water with more than 10 parts per billion can increase the risk of certain cancers.

The change conforms to tighter federal standards set by the Environmental Protection Agency. In Snohomish County it currently applies only to new construction, not existing wells. Effective immediately, building permits for new homes with individual wells will be approved only if drinking water does not exceed 10 parts per billion. The Board’s decision also revises the rule to allow treatment of water with arsenic at levels between 10 and 150 parts per billion. In 2006, the new limit also will apply to existing public water systems throughout the country.

“Arsenic is among a number of contaminants that occur naturally in our local water,” said M. Ward Hinds, MD, MPH, head of Snohomish Health District. “Residents who drink from wells want safe water to drink,” he said, “so it makes good sense to test their water source before they commit to building.”

The health risks of ingesting low levels of arsenic over a lifetime can include damage to a person’s cardiovascular and nervous systems, and a higher chance of developing some cancers.

The Health District provides bottles for collecting water samples. Sample testing costs about $15 to $17 per contaminant. Systems to treat higher levels of arsenic are available from private vendors. Such systems must be checked for effectiveness by the Health District.

More information about arsenic in drinking water is available on the EPA’s Web site: To ask questions or request testing instructions from Snohomish Health District, call 425.339.5250.

Established in 1959, the Snohomish Health District works to improve the health of individuals, families and communities through disease prevention, health promotion, and protection from environmental threats. Find more information about the Health District at