Steps to Take in Response to Potential Well Contamination From Flooding Events
The Cayuga County Health and Human Services Department recommends that if the area around a homeowner’s well gets flooded or if it is suspected that the well is contaminated due to flooding, the well should be disinfected and then tested for bacteria contamination before using it for drinking water or for cooking.
Until testing shows that the water is free of contamination, the water should be boiled for one minute and then cooled before usage or bottled water should be used. If flooding and groundwater contamination is extensive, your well may not be a suitable source of drinking water for some time.
Severe flooding that damages the well casing, deposits debris around the well or submerges electrical controls will require a qualified professional for evaluation, servicing and disinfection.
Procedures for Disinfecting a Well
Drilled Well: 1 to 1 1/2 gallons of any household bleach per 100 feet of well.
Dug Well: 1/2 to 1 gallon of bleach per 25 feet of well.
There are also chlorine tablets available, they are more concentrated than liquid bleach (if you use these tablets, crush them before you put them into the well to make sure they dissolve, remember to be careful doing this, heat is generated).
Pour half to three quarters of the chlorine into the well (dug or drilled well) washing down the sides of the well casing as best you can.
Run water from each tap (including dishwasher, washing machine, any outside faucets and run a hot water tap to get chlorine into the hot water tank) until a chlorine odor appears. Pour the remainder of the chlorine into the well, again taking measures to wash down the sides of the casing or pit.
Allow the system to stand idle for at least 8 hours (overnight would be sufficient). The chlorine can be flushed from the system with normal use (remember if you have chlorine in the line to your washing machine you want to remove it before doing a load of laundry).
After chlorine odor is gone, wait a few days, then take a sample to a private laboratory for bacterial analysis to determine whether contamination has been eliminated.