OREGON STATE UNIVERSITY

Private well water often unsafe after major floods

01/19/2012

CORVALLIS, Ore. – The catastrophic flooding unleashed on western Oregon and Washington in the past few days raises an additional, serious and immediate concern for many, if not most people who get their water from private wells – contamination that makes the water unsafe to drink.

Due to the extent of flooding, Extension well water experts at Oregon State University say residents with wells in this area should be very cautious about water that may have been contaminated by surface pollutants.

Warning signs include sediment, cloudiness, “off” smells, or excessive puddling near the well. Water should be absolutely clear.

Well water contamination can be serious and affect everything from parts of the well to your health,” said Chrissy Lucas, an OSU Extension groundwater protection education program assistant. “It should be treated as an emergency. If you have any doubts at all, the first priority is to drink or cook with bottled water or water treated for an emergency situation.”

Heavy rains, flood water and extensive standing water, Lucas said, can bring contaminants from the surface quickly down into the well. Normally, groundwater from wells has moved slowly through the soil, naturally filtering and breaking down any potential contaminants before people drink it.

Contaminants can include bacteria, sediments, heavy metals, oils, fertilizers, pesticides, almost anything found on the surface. Deeper wells sometimes have fewer problems, Lucas said, but provide no guarantee of safety. Wells more than 10 years old or less than 50 feet deep are more likely to be susceptible to contamination, experts say.

If water must be used before bacterial safety tests are made, water should first be boiled for one minute, followed by an addition of eight drops of unscented bleach – about one-eighth of a teaspoon – to each gallon of water. Then let the water sit about 30 minutes before using it.

The best protection, she said, is for people to have their water tested at a private laboratory before use. If it has been contaminated, treatment may be necessary. The problem can continue for months after the flood is over until the well is properly treated.

More detail on these issues can be found online in two documents produced by the Environmental Protection Agency, at http://1.usa.gov/i9eO1I and http://1.usa.gov/cjpOEy

Local health department officials and OSU Extension offices can help provide more information, Lucas said. A toll-free Safe Drinking Water Hotline is also available, at (800) 426-4791, and a range of information is at the OSU Well Water Program web site at http://bit.ly/yOouMK