Wells don't usually freeze at the bottom — the earth below the frost line stays a steady 45–55°F all winter, and your pump sits comfortably in it. Wells freeze at the top: the pitless adapter connection in a shallow trench, the exposed pipe in an uninsulated pump house, the pressure tank in a vented crawl space, the hydrant left half-drained. One hard night at 5°F finds the weak link, and you wake up to no water — or worse, to the sound of a burst line thawing at noon.
Winterizing a well system is a half-day of cheap work in October that prevents the most miserable failure mode rural homeownership offers. Here's the complete list, in order of what freezes first.
Know Your Frost Line
Everything below the local frost line (6 inches in the South, 4+ feet in the northern tier) is safe year-round. Everything above it is on your list. The classic vulnerable points: the top few feet of the well casing, water lines passing through crawl spaces and rim joists, the pressure tank and switch, outdoor hydrants and spigots, and any above-ground pipe run to a barn or coop.
The Wellhead
- Insulate the exposed casing. An insulated well head cover (the fake-rock or bag styles both work — R-value matters, looks don't) traps ground heat rising along the casing. In hard-freeze country, add a bag of leaves or straw around (never sealing the cap vent) for pennies.
- Don't let the cover create a critter condo. Mice chew wire insulation; check that the well cap itself is sealed and vermin-proof.
- Well pits: if your well lives in a pit, insulate the lid and walls, and make sure the pit drains — a flooded pit that freezes is a casing-cracker. (Long-term: pits are obsolete for good reason; budget a pitless conversion.)
The Pump House / Crawl Space
This is where most freezes actually happen — the pressure tank, switch, and exposed piping.
- Seal the drafts. A pinhole draft at -10°F freezes a pipe behind an insulated wall. Foam, caulk, close vents.
- Wrap the pipes. Heat tape (heat cable) with a built-in thermostat on every exposed run, then foam pipe insulation over the tape (check the tape's rating allows covering). Thermostatic tape draws power only below ~38°F — cheap to run.
- Protect the tank and switch. The pressure switch's thin sensing tube is often the first casualty — it freezes, the switch reads zero, the pump either won't run or won't stop. An insulated tank jacket, or a thermostatically-controlled space heater or heat lamp in the pump house, keeps the whole cluster above freezing. A remote temperature sensor/alarm ($25) that pings your phone at 35°F is the cheapest insurance in this entire article.
- A dripping faucet is not winterization. It reduces burst risk on marginal nights but wastes water, can overwhelm a septic in deep cold, and does nothing for the pump house. Fix the insulation instead.
Outdoor Fixtures
- Frost-free hydrants drain themselves only if the hose is disconnected — a connected hose traps water in the standpipe and splits it. Disconnect every hose in October.
- Standard outdoor spigots: shut the interior supply valve, open the spigot to drain, add an insulated cover.
- Irrigation lines: drain or blow out with compressed air before the first freeze.
Vacant Property? Drain It Instead
For a cabin or house left unheated, don't fight the freeze — surrender the water:
- Kill power to the pump.
- Open the lowest drain and all faucets (both handles); drain the pressure tank completely.
- Drain the water heater (power/gas off first).
- Blow lines out with a compressor if possible; pour non-toxic RV antifreeze in traps and toilet bowls — never in the well or supply lines.
- Leave faucets open. The pump and the water down-hole take care of themselves below the frost line.
If a Pipe Freezes Anyway
No water at one fixture on a frozen morning: open the tap, warm the suspect pipe with a hair dryer or heat gun from the tap end backward — never a torch, and never leave heat unattended. No water anywhere: check the pressure switch and its sensing tube first (thaw gently), and kill pump power if you suspect ice blockage — a pump dead-heading against an ice plug overheats.
Your Action Plan
- Every October (or when nights first touch 28°F): wellhead cover on, heat tape checked and plugged in, pump house sealed, hoses off hydrants, spigots drained and covered.
- Test the heat tape — most have an indicator; a dead tape discovered in January is a bad discovery.
- First hard freeze: walk the system once — listen for the pump short-cycling (a symptom of a freezing sensing line).
- Spring: reverse it — covers off, tape unplugged, hydrants checked for winter damage.
The whole discipline is a date problem: winterization done November 20th instead of October 20th is a coin flip on the first cold snap. Put the fall checklist in the WellKept app as a recurring October reminder — it holds the list (your list, with your property's quirks: "heat tape on the barn run, check the coop hydrant"), and the spring reversal too. One reminder, twice a year, versus one burst pipe: the math does itself.
Frequently Asked Questions
At what temperature will my well pump freeze? The submersible pump itself won't — it sits below the frost line in ground that stays 45–55°F. What freezes is exposed infrastructure: wellhead piping, pressure tanks, switches, and above-ground runs, which are at risk whenever air temperature holds below ~28°F for several hours, especially with wind.
How do I keep my well pump house from freezing? Seal drafts, wrap exposed pipes in thermostatic heat tape under foam insulation, insulate the pressure tank, and add a thermostatically controlled space heater or heat lamp for hard-freeze nights. A $25 WiFi temperature alarm that alerts your phone below 35°F catches the failure before the pipes do.
Should I let my faucets drip to keep well pipes from freezing? It's a last-resort tactic for a marginal night, not a winterization plan. On a well, constant dripping cycles your pump, wastes stored pressure, and can overload a septic system in prolonged cold. Insulation and heat tape solve the problem; a drip only postpones it.
How do I winterize a well for a vacant house? Shut off pump power, drain the pressure tank and all lines from the lowest point, drain the water heater, blow out lines with compressed air if possible, and add RV antifreeze to traps and toilets only — never to the well or supply plumbing. The well itself needs nothing; it's below the frost line.
What happens if my pressure tank freezes? Ice inside the tank or its connections blocks flow and can split the tank tee or the pressure switch's sensing tube — the switch then misreads pressure and the pump won't run, or runs continuously. Thaw gently, then inspect for cracks before trusting the reading; a frozen-and-thawed switch that behaves oddly should be replaced.