What to Do With Your Well Water After a Flood in Maryland
July 5, 2026 · 5 min read · By Deep Dive Plumbing Maryland
Do not use your well water after flooding until it has been shock chlorinated and tested negative for bacteria. Use bottled water for drinking, cooking, and brushing teeth.
Maryland's Chesapeake Bay watershed is prone to flooding — from tropical storms, nor'easters, and heavy summer rain events. When floodwater reaches your wellhead, it can introduce bacteria, sewage, agricultural chemicals, and other contaminants directly into your water supply. Here is the step-by-step process to safely restore your well.
Step-by-Step Well Restoration After Flooding
Do not use the well
Until the well has been tested and treated, use bottled water for drinking, cooking, and brushing teeth.
Inspect the wellhead
Check the well cap and casing for damage, debris, or signs that floodwater entered. Document with photos.
Pump out the well
Run the pump until the water runs clear. This removes the initial flood-contaminated water from the well.
Shock chlorinate
A licensed plumber introduces chlorine into the well to disinfect the casing, pump, and distribution system.
Flush and wait
After the chlorine contact time (12–24 hours), flush the system until the chlorine smell dissipates.
Test the water
Have the water tested by a certified lab for bacteria (total coliform and E. coli) before resuming use. Wait 5–7 days after flushing before testing.
Frequently Asked Questions
Is my well water safe after a flood?
No — not until it has been tested and treated. Floodwater carries bacteria, sewage, agricultural chemicals, and other contaminants. Even if the water looks clear, it may be contaminated. Do not drink, cook with, or brush teeth with well water after flooding until the well has been shock chlorinated and tested negative for bacteria.
How long does it take to restore a well after flooding?
The process typically takes 3–7 days: 1 day to pump out and chlorinate, 12–24 hours for chlorine contact time, 1–2 days to flush, and 5–7 days to wait before testing. If the first test comes back positive for bacteria, the process must be repeated. In some cases, structural repairs to the well are needed before the well can be safely restored.
Does homeowners insurance cover well contamination from flooding?
Standard homeowners insurance typically does not cover flood damage, including well contamination. Flood insurance (through FEMA's National Flood Insurance Program or a private insurer) may cover well remediation costs. Check your policy and contact your insurer promptly after a flood event.
What if my well keeps testing positive for bacteria after flooding?
Repeated positive bacteria tests after shock chlorination indicate a persistent contamination source — usually a compromised well cap, cracked casing, or inadequate grout seal that is allowing surface water to continue entering the well. The well needs a structural inspection and repair before the contamination problem can be resolved. A UV treatment system provides ongoing protection while the source is investigated.
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