A well that’s been inundated with floodwater could end up with debris, bacteria, and other contaminants in your drinking water. It has to be cleaned out and tested before it’s safe for humans and animals to use. Because wells are complicated, you’ll need to get ahold of a licensed water well contractor to do any servicing of a flooded well.

Michael Schnieders is a hydro-geologist with Water Systems Engineering in Ottawa, Kansas. He says one of the first steps is to purge the well.

"The necessary time required to pump the well is dependent on the well size and design, the aquifer and the flood water depth and quality. As few as three-hours, and as many as 24-hours may be needed," he says. "It’s recommended you purge the well until visual turbidity is gone. Visual turbidity is the means of evaluating a sample visually against an opaque background for signs of contamination or sediment."

Take the well pump apart to clean it separately. Then, remove any sediment or debris that has collected in the lowest extension of the well.

Schnieders says the chemicals used for disinfection should be approved for potable water and selected based on suspected contaminants and the materials used in the well’s construction.

"Key steps in the process include using the correct dosage, targeting the entire well system with an adequate treatment volume, adjusting the pH if you live in a hard water or alkaline water area, and allowing sufficient contact time for the solution," he says.

All associated piping and pumping equipment should also be disinfected with the solution. Before you take even a sip of water from the well, have it tested for total coliform bacteria.