DRINKING WATER PROTECTIONMinnesota Department of Health

Randy Ellingboe

Chris Elvrum

• Contaminants in drinking water create potential for disease• Chemicals• Pathogens (bacteria, protozoans, viruses)

• The Good News:• MN Public water supplies are doing a good job at protecting public

health, and compliance with the Safe Drinking Water Act is very high (>99%)

• Majority of private wells provide a safe adequate supply

• The Bad News: • Some private water supplies at risk – knowledge limited• Number of potential contaminants increasing, most unregulated

• Pressing need to evaluate impacts on public health2

Groundwater and Public Health

Minnesota’s Drinking Water Sources

Public Water Supply: Groundwater2.7 million people

73 % from groundwater

Wells in Minnesota

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• Public Water Supply Wells serve 2.7 million people

• 11,000+ Public Wells

• Private Wells serve 1.2 million people

• ~250,000 Private Wells in operation

GW Quality for Drinking Water

• Groundwater sources across the state vary widely in quality, from those sources that require no treatment to those that are much like surface water sources

• Surface water and groundwater under the influence of surface water always requires a substantial amount of treatment

Groundwater QualityContaminants – naturally-occurring

& anthropogenic• Microbiological

• Bacteria, Viruses etc.

• Chemical• Arsenic, Nitrate, PFCs

• Radiological • Radium

• Contaminants of Emerging Concern

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Contaminants of Emerging Concern• Society uses a lot of chemicals

• 42,000 chemicals + 40,000 polymers in common use

• Science is better at looking for and finding chemicals• Looking for more chemicals in more places • Better laboratory analytical tools / lower detection limits

• There are new ways to measure toxicity • Low doses / subtle effects

• We have toxicity data on a limited number of chemicals• Drinking water advice on a few hundred

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Testing Drinking WaterPublic Water Supplies•Safe Drinking Water Act - covers100+ contaminants•Frequency and number of parameters tested in finished water varies, depending on risk

Private Wells•Arsenic, Nitrate, and Bacteria•Testing at time of well construction. No additional testing or treatment required

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Source Water Protection“Preventing contamination by managing potential sources in a well’s recharge area”

Required in MN rule for groundwater source systems

More effective and cost-efficient than clean-up, treatment or drilling a new well

*Private supplies protected by well construction code

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Drinking Water Summary

• Essential to economic growth and development• Human activities impact quantity and quality• Contaminants both naturally occurring and anthropogenic

• Unregulated contaminants a challenge• Protection is key for public health

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