Is my well pump actually bad?
Most symptoms blamed on a well pump are caused by a cheaper part. This works out which one before anybody pulls anything.
The short answer
Usually not. The symptoms people read as a failing pump — rapid cycling, weak pressure, a pump that never stops — are more often a waterlogged pressure tank, a worn pressure switch, a clogged filter or a leak. Check those first: they cost tens of dollars, and pulling a pump costs thousands.
Tick a symptom to see what actually causes it, ranked, with the cheap causes separated from the expensive one.
Three parts, and only one of them is expensive
A well water system has a pump down the well, a pressure tank in the house, and a pressure switch between them telling the pump when to run. All three produce overlapping symptoms, and only one of them requires pulling several hundred feet of pipe out of the ground to replace.
That asymmetry is the whole reason to diagnose carefully. A pressure switch is about $20. A pressure tank is a few hundred. A submersible pump replacement runs into four figures, most of which is the labour of getting it out.
| Part | Why it gets blamed |
|---|---|
| Pressure tank | The cheapest thing to be wrong, and the most commonly misdiagnosed as a dead pump. |
| Pressure switch | A $20 part that mimics almost every pump fault. |
| Pump or motor | The expensive answer. Worth ruling the cheap ones out first. |
| The well itself | Water level, yield or casing — not the equipment. |
| Plumbing or fittings | A leak, a stuck valve or a clogged filter downstream. |
| Electrical supply | Wiring, capacitor or control box rather than the motor. |
Rapid cycling is a tank fault, not a pump fault
This is the single most expensive misdiagnosis in well water, and almost every article on the subject files it under “signs your pump is failing”.
A pressure tank is an air spring. A sealed cushion of air above a bladder gets compressed as the pump fills the tank, and pushes water back out as you use it. When that bladder fails, or the air pre-charge leaks away over years, there is almost no stored water left. The pump starts, fills what little remains in a few seconds, hits cut-out, stops — and repeats the moment you draw again.
The pump in that scenario is working perfectly. It is being asked to start dozens of times a minute, and the starting is what will eventually kill it. Replace the pump and the new one will short-cycle exactly the same way.
Test it in five minutes: cut the power, open a tap to drain system pressure, then put a tyre gauge on the schrader valve at the top of the tank. It should read 2 psi below your cut-in pressure — 38 psi for a 40/60 switch. Near zero, or water spitting out of the valve, means the bladder has gone.
The order to check things in
Cheapest and most reversible first. Every step here is something you can do yourself or ask a contractor to confirm before authorising anything larger.
- Is the breaker on and holding? A tripped well breaker is common after a storm. If it trips again immediately, stop and get an electrician — repeated resets on a shorted motor are a fire risk.
- What does the pressure gauge do? Watch it through a full cycle. Pressure that climbs and falls in seconds points at the tank. Pressure that climbs slowly and never reaches cut-out points at the pump or a leak.
- Check the tank pre-charge. As above. This one test resolves a large share of all well complaints.
- Look at the pressure switch contacts. Power off, cover off. Pitted, blackened or welded contacts explain a pump that will not start or will not stop.
- Rule out a leak. Close the main valve into the house with the pump off and watch the gauge. Falling pressure means the leak is on the well side; holding pressure means it is in the house.
- Change the sediment filter. A neglected cartridge throttles the whole house and imitates a weak pump for the price of a coffee.
- Only then consider the pump. By this point you have eliminated everything cheap, and a contractor has something useful to work from.
Every cause, and how to confirm it
The tool above ranks these against your symptoms. In full, with the observation that settles each one:
| Cause | How to confirm | Typical cost |
|---|---|---|
| Waterlogged pressure tank (failed bladder or lost pre-charge)Pressure tank | Cut the power, open a tap to drain the pressure, then check the schrader valve on top of the tank with a tyre gauge. It should read 2 psi below cut-in. If it reads near zero, or water sprays out, the bladder has failed. | $40–$120 to re-charge with air; $300–$700 to replace the tank |
| Failed or fouled pressure switchPressure switch | Pull the switch cover with the power off and look at the contacts. Pitted or blackened contacts, or a rapid chattering click when the pump tries to start, point here. | $20–$60 for the part; $150–$300 with a call-out |
| Clogged sediment filter or closed valvePlumbing or fittings | Compare pressure before and after the filter housing, or simply fit a fresh cartridge. If pressure returns, that was it. Also check the main and bypass valves are fully open. | $10–$40 for a cartridge |
| Water level dropping below the pump intakeThe well itself | Air spitting that gets worse the longer water runs, and recovers after the well rests for a few hours, is the signature. A steady leak does not behave that way. | Free to observe; $800–$3,000 to lower the pump or deepen the well |
| Leak in the drop pipe, pitless adapter or house plumbingPlumbing or fittings | Shut the main valve to the house with the pump off and watch the gauge. If pressure still falls, the leak is between the pump and that valve. If it holds, the leak is inside the house. | $150–$400 for house plumbing; $800–$2,500 for a drop pipe or pitless adapter |
| Worn pump end (impellers)Pump or motor | Pressure that builds slowly and never quite reaches cut-out, with the pump running fine electrically, and no leak found. Usually arrives gradually over months. | $900–$2,500 installed, depth dependent |
| Failed pump motorPump or motor | No water at all, and the breaker trips immediately or the motor hums without starting. An electrician or well contractor can confirm with a resistance and insulation test at the control box. | $900–$2,500 installed; more on a deep well |
| Control box, capacitor or wiring faultElectrical supply | A motor that hums but will not start, or trips on start rather than while running, points at the capacitor or relay rather than the motor itself. | $60–$250 for the box; $150–$400 fitted |
| Deteriorating well screen or casingThe well itself | New sand or grit in the water with no plumbing work having been done, often with pressure gradually falling as the impellers wear. | $400–$1,200 to investigate; repairs vary widely |
Costs are planning ranges compiled from published pricing, not quotes. Depth drives pump replacement cost more than anything else, because most of the bill is the labour of pulling and re-setting the pipe.
Frequently asked questions
- How do I know when my well pump is bad?
- A genuinely failed pump usually means no water at all, or a breaker that trips the moment it tries to start. Weak pressure, rapid cycling and a pump that runs constantly are more often the pressure tank, the switch, a leak or a clogged filter — all far cheaper to fix.
- What causes a well pump to short cycle?
- Nearly always a pressure tank that has lost its air charge or whose bladder has failed, so there is no stored water between cut-in and cut-out. A tank that was undersized for the pump in the first place does the same thing. It is rarely the pump itself.
- Why does my well pump keep losing prime?
- On a submersible, genuine prime loss usually means the water level has fallen to the pump intake, or there is a leak in the drop pipe or a failed check valve letting water run back down the well. Submersibles do not need priming in normal operation.
- How long does a well pump last?
- Commonly 8 to 15 years, though sand in the water, frequent starting and running against a closed valve all shorten it considerably. A pump that short-cycles for years will fail early, which is why fixing the tank matters even when the pump still works.
- Can I replace a well pump myself?
- Pulling a submersible means handling hundreds of feet of pipe, wire and a heavy pump, plus the electrical connection at the control box. It is done by capable homeowners with the right equipment, but the wire splice and the torque arrestor have to be right or the job fails expensively. Most people should not.
- Is it the pump or the pressure tank?
- Watch the pressure gauge through a cycle. Pressure swinging up and down within seconds is the tank. Pressure that rises slowly and stalls below cut-out, with no leak found, is the pump. No pressure at all with a humming or tripping motor is the pump or its control box.