Public Service Announcement
Public Health


Flooding: Water and on-site sewage system recommendations, disinfection of private wells

Kittitas County, WA - 01/18/2011 - Flooding of a well or an on-site sewage system can lead to health concerns such as contaminated drinking water, sewage back-up into homes, or a lack of sanitation in the case of an on-site sewage system failure. Illnesses related to these types of contamination can cause nausea, vomiting, diarrhea, or more serious symptoms.

On-site sewage system recommendations

During the flood, limit or discontinue the use of an on-site sewage system until the water in the drainfield is lower than the water level around the house.  If the soil is saturated wastewater will not be treated and will become a source of pollution.   Also, shut off power to sewage lift pumps used in some systems (mound, pressure, at-grade) until water recedes.

After the flood, try not to compact the soil over the drainfield by driving or operating equipment in the area when the soil is still saturated.  Saturated soil is more susceptible to compaction; this can reduce the ability of the drainfield to treat wastewater and can lead to system failure.  If damage to a system is suspected it should be professionally inspected and serviced.  Most septic tanks are not damaged by floods because they are below ground and completely covered.  Contact the Kittitas County Public Health Department to report an on-site sewage system failure at (509) 962-7515.

Water recommendations

Those who use well water from an individual well or a water system that services less than 15 homes should have a water sample tested for bacterial contamination before any further water consumption if there was the potential for the well to have been contaminated.  Contamination can occur if the wellhead was submerged at any time in standing flood water.  Normal snowmelt around the wellhead is not a potential source of contamination.  Water should also be tested if there is a change in odor, taste, color, or clarity.  Drink bottled water or boil water in a covered container for three minutes or longer until test results are received that show the water is safe to drink.

Water systems that service more than 15 homes are run by certified water operators.  Users of these systems will be contacted by their water operator if there are any changes to the water supply.

Water test kits can be picked up at the Kittitas County Public Health Department in Ellensburg or at Evergreen Valley Utilities in Cle Elum.  Contact information is listed below.  Cost for the bacteria test is $20.  Verbal results can be received as soon as the next day.

Kittitas County Public Health Department
507 N Nanum Street, Suite 102
Ellensburg, WA 98926
(509) 962-7515

Evergreen Valley Utilities
301 W 1st Street
Cle Elum, WA 98922
(509) 674-9642

Disinfection of private wells

If a bacteria test is returned showing that a well is unsafe, private well owners can disinfect their well using common household liquid bleach if the well cover was properly sealed.  If the well cover was not properly sealed and dirt and debris were deposited in the well, more cleaning would be required.

To disinfect a private well, follow the instructions on the attached document.  Water should not be consumed from the well immediately after disinfecting.  Instead, the well should be tested for bacteria again after the disinfection.  If the test result shows that bacteria are still present, the disinfection process should be repeated.  Water should not be consumed from the well until bacteria test results are returned that show the water is safe to drink.  Additional bacteria samples should be taken two to four weeks and three to four months after the first test showing no bacteria is returned.

Kittitas County, from the Cascades to the Columbia, and online at


Contact: Kittitas County Public Health Department, (509) 962-7515