The snow came off fast, the ground was still frozen underneath, and now there is standing water in the low spot where your wellhead sits. Maybe it drained by afternoon. Maybe it sat there for two days.
Either way, the question is the same and it is worth taking seriously. A wellhead sitting in surface water is the one situation where the barrier between everything on the ground and everything in your drinking water can be crossed directly. Runoff carries whatever it has traveled across, which around here can mean livestock manure, septic drainfields, orchard chemicals, road runoff, and whatever was in the soil.
The good news is that a properly constructed, undamaged wellhead is designed to keep surface water out, and most flooding events end with nothing wrong. The bad news is that the wells most likely to flood are frequently the older ones least equipped to resist it. This guide covers how to tell the difference, what to do immediately, and how to confirm your water is safe rather than assume it.
If your wellhead has been underwater and you are unsure whether the water is safe to drink, call us at (509) 300-5151.
Why This Matters More Than It Looks
A well is a hole that goes straight down past every natural filter the ground provides. Everything about well construction, the casing, the grout seal around it, the sanitary cap on top, exists to make sure the only water entering that hole comes from the aquifer rather than from the surface a few feet away.
Surface water is not treated and not filtered. Runoff moving across a pasture, past a septic drainfield, or down a road ditch picks up bacteria, nitrates, sediment, fuel, and agricultural chemicals along the way. Groundwater is generally protected from all of that by many feet of soil that filters and breaks down contaminants over months or years of slow travel. Standing water at a wellhead skips every bit of that protection.
Coliform bacteria are the standard indicator, and they are the most common finding after a flooding event. Coliform itself is often harmless, but its presence means surface material reached your water, and whatever else was in that surface material likely came with it. Coliform bacteria in well water covers what a positive result actually means.
Nitrate is the second concern, especially in agricultural areas across the Columbia Basin, and it is genuinely dangerous for infants. Nitrates in well water covers the health thresholds.
Turbidity and sediment are usually the visible symptom. Cloudy or muddy water after a runoff event is a strong signal that a direct pathway opened up, though clear water is not proof that nothing got in.
The EPA’s private well owner resources are worth reading on this specific scenario, because flooding is one of the few events where they recommend acting before you have test results rather than after.
Which Wells Are Most at Risk
Not every wellhead is equally vulnerable, and knowing where yours sits tells you how worried to be.
Wells in low spots and depressions collect water by definition. The wellhead should sit on ground that sheds water away from the casing, ideally on a small mound, with the casing extending well above grade. Washington requires casing to stand a minimum height above the ground surface for exactly this reason, and older wells frequently do not comply because the rule came later or because grade changed around them over the decades.
Pit wells are the highest-risk configuration there is. If your wellhead sits down inside a concrete pit or vault below ground level, that pit collects water and holds it against the casing. These were built for freeze protection generations ago and are now discouraged everywhere. If you have one, this article applies to you more than to anyone else.
Wells with damaged or missing sanitary caps are wide open. A cracked cap, a missing gasket, or a cap that was never a sealed sanitary type in the first place is a direct entry point. Well cap replacement covers what a proper one looks like, and it is one of the cheapest pieces of insurance on a property.
Wells with compromised casings or failed grout let water enter below the surface where you cannot see it. A corroded steel casing on a well from the 1960s is an obvious candidate. So is a well where the annular seal around the outside of the casing has degraded, creating a channel straight down alongside the pipe. Well casing repair covers the symptoms.
Shallow wells are more exposed than deep ones, simply because there is less material between the surface and the water.
And proximity matters. A wellhead near a septic drainfield, a corral, a manure pile, or a chemical storage area has more to worry about in runoff than one in the middle of an open field. Septic to well separation distances in Washington covers the required setbacks.
What to Do Right Away
Order matters here, and the first steps are about safety rather than water quality.
Stay away from electrical components if any part of the well system is wet. Pump wiring, a pressure switch, a control box, or a disconnect sitting in or near standing water is a serious hazard. If the equipment is submerged or the ground around it is saturated, turn the circuit off at the breaker panel, not at the well, and keep clear until things dry out or an electrician or well contractor has looked at it.
Stop drinking the water until you know. This is the part people skip, and it is the whole point. Use bottled water for drinking, cooking, brushing teeth, ice, and pets until you have a clean test result. Boiling for a full minute kills bacteria and is a reasonable interim step, but it does not remove nitrate, chemicals, or fuel, and it actually concentrates nitrate. If runoff came off agricultural ground, do not rely on boiling.
Do not run the pump hard while the well is turbid. Pulling sediment through a pump wears it and can pack the intake. If the water is visibly dirty, minimize use rather than trying to flush the well aggressively on your own.
Look at the wellhead once it is safe to approach. Is the cap in place and intact? Is the casing standing above grade or has soil washed away around it? Is there any visible damage, separation, or a gap between the casing and the ground?
Document it. Photos of standing water at the wellhead are genuinely useful later, whether for a contractor, for insurance, or for a future buyer’s questions. Selling a property with an undisclosed contamination event is its own problem, and well disclosure when selling in Washington covers what has to be reported.
Shock Chlorination and Testing, In the Right Order
The sequence here trips people up constantly, and doing it backward wastes both time and money.
Test first if you can wait for results. A test taken before any chlorine goes in the well tells you what actually happened, which matters if you need to know whether there is an ongoing problem rather than a one-time event. Chlorinating first destroys that information.
Shock chlorinate second. This is the disinfection step, and it involves introducing chlorine into the well at sufficient concentration, circulating it through the entire plumbing system including every fixture and the water heater, letting it sit for a period of hours, and then flushing it all out. Done properly it kills bacteria throughout the system. Done casually, with a jug of bleach poured down the casing and no circulation, it treats the top of the well column and nothing else. Well shock chlorination covers the procedure properly.
Test again after the chlorine is fully flushed, and this is the step that actually matters. Testing too soon gives a false clean result, because residual chlorine suppresses bacterial growth in the sample. Wait until there is no chlorine detectable at the tap, which usually takes several days of normal use, then sample.
Then test a third time a few weeks later. This is the step almost everyone skips and it is the one that distinguishes a resolved event from an ongoing one. If the first post-chlorination test is clean and a follow-up several weeks out is also clean, the contamination was a one-time entry and it has been dealt with. If bacteria return, you do not have a contamination event, you have a construction defect letting surface water in continuously, and no amount of chlorine will fix that. The well needs physical repair.
What to test for depends on your surroundings. Coliform and E. coli always. Nitrate if there is any agriculture, livestock, or septic nearby, which covers most of this region. Beyond that, consider what the runoff actually crossed. How to read well water test results helps make sense of the report, and well water testing around Wenatchee covers where to get it done.
Fixing the Underlying Problem
If your wellhead flooded once in an unusual year, address the water quality and move on. If it floods regularly, chlorinating every spring is treating a symptom.
Regrading is the most common fix and often the cheapest. Building up the ground so it slopes away from the casing in every direction, and adding a diversion above the wellhead if runoff arrives from a predictable direction, solves a lot of these situations for the cost of a few hours of machine time.
Extending the casing brings a short casing up to a compliant height above grade. This is real work requiring a licensed contractor, but on a well that floods every year it is the permanent answer.
Eliminating a well pit is strongly worth considering if you have one. Converting a pit well to an above-grade wellhead with a pitless adapter removes the flooding pathway entirely and brings the well up to current standards. It is not a small job, but for a pit that fills every spring it is the right one.
Replacing the cap and repairing the seal are the cheap items on this list and should be done regardless. A sanitary cap with an intact gasket costs very little and closes the most likely entry point.
Repairing casing or grout is the expensive end, and it is what you are looking at if repeat testing shows recurring contamination. Washington’s well construction and maintenance requirements set the standards this work has to meet, and a well that cannot be brought up to them may need to be properly decommissioned and replaced.
When to Call
Handle the immediate steps yourself. Stop drinking the water, stay away from wet electrical equipment, and get a sample to a lab. Those cost almost nothing and they are the ones that matter most in the first 48 hours.
Call a professional if the wellhead or pump equipment was submerged, if the water stays cloudy or has an odor after the flooding subsides, if a test comes back positive for E. coli, if bacteria return after a proper shock chlorination, if you have a well pit, or if the casing shows any visible damage or has soil washed away from around it.
Call immediately rather than waiting if anyone in the household is pregnant, if there is an infant on formula, or if anyone is immunocompromised. Nitrate and bacterial risks are meaningfully higher for those groups and the precautionary threshold should be lower.
We handle post-flood inspections, shock chlorination, wellhead repairs, and pit conversions across Wenatchee, East Wenatchee, Cashmere, Leavenworth, Chelan, Quincy, and Moses Lake. Call (509) 300-5151 or request a free estimate.
Frequently Asked Questions
Is my well water safe to drink after the wellhead has been flooded?
Assume it is not until a test says otherwise. Use bottled water for drinking, cooking, ice, and brushing teeth until you have a clean result. Boiling for a full minute handles bacteria as an interim measure, but it does not remove nitrate or chemicals and actually concentrates nitrate, so it is not sufficient if the runoff crossed agricultural or livestock ground.
Should I shock chlorinate before or after testing my well?
Test first if you can wait for the results, because chlorine destroys the evidence of what actually got in. Then shock chlorinate, then test again only after all chlorine has flushed out of the system, since residual chlorine produces a false clean result. A third test a few weeks later is what tells you whether the problem is truly resolved.
Why does my well keep testing positive for bacteria even after chlorinating?
Recurring bacteria after a proper shock chlorination almost always means surface water is entering the well continuously through a physical defect rather than having entered once during an event. The usual causes are a damaged or non-sanitary cap, a casing that does not extend far enough above grade, a failed grout seal around the casing, or a below-grade well pit. Chlorine cannot fix any of those.
What should I do if my wellhead sits in a pit that fills with water?
Treat it as the highest-risk configuration there is, since the pit holds water directly against the casing. Short term, keep the cap sealed and test your water after any flooding. Long term, converting the pit to an above-grade wellhead with a pitless adapter eliminates the pathway entirely and brings the well up to current Washington standards.