Clark Fork River at Bonner Dam (then Clark Dam), 1908
Flood waters can infiltrate and contaminate private wells, springs, and cisterns. It is up to the owner to make sure the water is safe for consumption and domestic uses. After flooding, you should have the well disinfected and tested to make sure it’s safe.
The National Ground Water Association offers this information for wellowners, including actions to take in preparation for flooding: http://wellowner.org/
This DEQ Fact Sheet on Shock Chlorination Treatment of a well and water system offers a step-by-step approach to disinfecting a well or water system.
DEQ offers this Check Your Well website. DEQ also offers this site, go to Private Well Information. And this page of Important Information Links.
The State of Colorado offers this Fact Sheet on Residential Water Well Disinfection.
The State of Alaska offers this detailed Fact Sheet on Recovering from Flooded Drinking Water Systems.
Safe disposal of of wastewater is essential to protect human health. Flooding can cause septic tanks to fill causing sewage to back up. If you suspect your wastewater system has been compromised by flood waters, contact your county health department and a licensed septic system installer or a licensed plumber to have it assessed. Do not use or flush your toilets until you know that the septic tank and associated sewer pipes are intact; otherwise, wastewater could flow back up into the house through the toilet, shower, bath and laundry drains.
Butte-Silver Bow and DEQ offer this Fact Sheet on addressing Flooded Septic Tanks.
The Montana Guide to Septic Systems covers important information to protect and maintain your system.
Secure above-ground fuel storage tanks, including propane.
Preparing for Flooding
A number of precautions can be taken as soon as a flood warning is issued.
Move chemicals or hazardous materials above flood level to lessen the chance of spill or contamination.
Turn off power to underground storage tank systems.
Take a product inventory and water level reading to help account for possible product loss of storage tanks.
Secure all tank openings and make sure caps and other components are in good condition.