When high water reaches a Washington property, or the ground around a private well stays saturated for days, the water from the tap can change without warning. A private well is the homeowner's responsibility from start to finish. No city or utility tests it on a schedule, so the first real check often falls to you. This guide covers what to look at after a flood and what to do next.
Why flooding changes a well
Flood water carries silt, soil, and whatever sat on the surface: animal waste, septic overflow, fuel, fertilizer, and debris. If that water can reach the well casing, the top of the well, a pit, or a cracked seal, it can move into the supply. Washington is in Franklin County, where many homes draw on groundwater and some properties sit in the Missouri River bottomland. Wells in that area often already carry heavy iron and very hard minerals, so a flood can make an existing problem look worse or introduce something new.
Start with the outside of the well
Before you test anything, walk the property and look at the well itself.
- Check that the well cap is in place, tight, and free of cracks.
- Look for standing water, mud, or debris around the top of the casing or inside any pit.
- Note any sign that the ground settled, shifted, or washed away near the wellhead.
- Check the electrical box and pressure tank for water damage. Do not work on wet electrical parts yourself.
Write down what you find, with dates and photos. If anything looks damaged, have a licensed well contractor inspect the system before you run the pump again.
Do not assume clear water is safe
Water that looks clear and smells normal can still carry bacteria after a flood. Until a lab result comes back, treat the supply as untested. Many homeowners use bottled water for drinking and cooking in the meantime. Ask your county health department or state environmental agency what they currently recommend for private wells after flooding, since guidance can change with conditions.
Testing for bacteria first
The most common post-flood test checks for total coliform bacteria and E. coli. Coliform bacteria indicate that surface water or other contamination may have reached the well. A positive result tells you the supply needs attention before anyone drinks it. Collecting a clean sample matters, so follow the lab's instructions closely.
- Choose a drinking water lab that accepts private well samples and ask whether it supplies the correct bottle and cooler.
- Collect the sample from an indoor cold tap placed before any filter, softener, or other equipment.
- Let the water run for the time the lab specifies, then fill the bottle without rinsing it or touching the inside of the cap.
- Keep the sample cold and deliver it to the lab within the time window the lab sets.
- Record the date, the tap used, and any flood notes on the chain of custody form.
Other tests to consider
Bacteria are the first concern, but floodwater can also move chemicals into groundwater. Ask the lab about nitrate if fertilizer or septic systems were near the well, since nitrate is a common contaminant from those sources. Ask about metals or fuel-related compounds if there was a spill, tank, or industrial site nearby. Homeowners on deeper wells in the area may also want to check for radium, and for hydrogen sulfide if there is a rotten egg smell. Those issues come from local geology rather than the flood itself, but a flood does not clear them out.
Reading the results
A lab report lists each item tested, the result, and a reference point for comparison. Read the bacteria line first. If coliform or E. coli is reported as present, stop using the water for drinking and cooking. Keep it off-limits until a professional has inspected the well, disinfected it if needed, and a follow-up sample comes back clean.
For chemical results, look for any item listed above its reference point and ask the lab what it means for your household. Treatment decisions come after you know what is actually in the water, not before. A single report is a snapshot, so plan to test again.
What to do next
- Keep bottled or otherwise safe water for drinking until you have results in hand.
- Store the chain of custody copy and the lab report together with your well records.
- Set a retest schedule with your lab, and repeat testing after every future high water event.
- If the well or equipment is damaged, book an inspection with a licensed well contractor before restarting the system.