Troubleshooting
How to Tell if Your Well Pressure Tank Is Bad
A failing tank shows up as short pump cycles and jumpy pressure long before it leaks. Five checks, none of which require opening anything electrical, will tell you where it stands.
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A well pressure tank is bad when it no longer holds an air cushion or is no longer structurally sound. The clearest signs are water coming out of the air valve (failed diaphragm or bladder), an air charge that keeps disappearing, rust or weeping at seams and fittings, and a pump that starts every time you open a faucet. A tank with water on its air side, or with corrosion, should be replaced — not recharged.
New to how the tank works? Our well pressure tank guide explains the air cushion, drawdown and precharge in two minutes.
Signs a pressure tank is failing
| Sign | Usually means | Next step |
|---|---|---|
| Pump clicks on with every faucet use | Little or no drawdown: waterlogged or very low air charge | Checks 2–4 below |
| Pressure falls fast, then jumps back | Lost air cushion | Check 3 |
| Water spits from the air valve | Failed diaphragm or bladder | Replace tank |
| Air charge low again weeks after being set | Leaking air valve or internal failure; possible corrosion | Replace tank (see the Amtrol warning below) |
| Rust, bulging, weeping seams, wet floor | Shell or fitting failure | Replace tank; turn power off if actively leaking |
| Tank sounds full to the top when tapped | Water-filled air side (a rough clue only) | Confirm with check 3 |
Why "just add air" can be dangerous
Amtrol's residential tank manual warns that adjusting the precharge or adding pressure to a tank that is corroded, damaged or has lost integrity can make it burst or explode, and that a loss of air — or a pump cycle that has become shorter than when the tank was new — can indicate internal corrosion.[1] That's why the checks below are observations. Decide on recharging only after you know the tank is sound.
Five checks, in order
Check 1: Look at it
With a flashlight, inspect the shell, the bottom seam, the base ring and the fittings on the tank tee. Rust streaks, bubbling paint, a damp base or a mineral crust at a seam are all reasons to replace the tank. Check the air valve cap too; a missing cap lets the valve core corrode.
Check 2: Time one pump cycle
Open a faucet and time how long the pump runs from cut-in to cut-out. Franklin Electric says a pump motor should run at least one minute per start.[2] If yours runs a few seconds, the tank isn't storing much water. The full method is in short cycling: time it.
Check 3: The air-valve check (the decisive one)
Safe to check
- Turn off the pump's breaker.
- Open a faucet near the tank and let it run until the flow stops and the gauge reads zero. The Water Systems Council's precharge sheet describes the same sequence: shut off power, open a faucet near the tank, drain completely.[3]
- Remove the cap on the tank's air valve (usually on top). Press the valve pin briefly.
| What comes out | What it means |
|---|---|
| Water, or a spray of air and water | The diaphragm or bladder has failed. Replace the tank. |
| Nothing at all | No air charge. On a diaphragm tank this often means a failure; have it evaluated before any recharge. |
| A firm hiss of dry air | Air side intact. Go to check 4. |
Check 4: Measure the precharge
With the tank still empty, read the air valve with a tire gauge. It should be 2 psi below your pump's cut-in pressure — 28 psi on a 30/50 system, 38 psi on 40/60.[1][4] The precharge calculator gives the target for any setting.
- Within a psi or two: the tank is probably fine; look elsewhere (check valve, leak, switch, tank size).
- Low, on a tank that's newer and shows no corrosion: the precharge can be reset following the manufacturer's instructions — Amtrol's procedure is to drain the tank, check, then release or add air to 2 psi below cut-in.[1] Re-check it in a few weeks.
- Low again after being reset, or low on an older or rusty tank: replace it.
Check 5: The bucket drawdown test
Measure how many gallons the tank delivers between cut-out and cut-in with the pump off, and compare with what a tank that size should deliver. At 30/50 psi a healthy tank gives roughly 30% of its total volume; at 40/60, about 26%.[5] Step-by-step: the bucket drawdown test.
What "waterlogged" means
A waterlogged tank has lost its air cushion, so it fills almost completely with water and can no longer deliver stored water between pump starts. In a diaphragm or bladder tank, that happens when the membrane fails or the air charge leaks out. In an older air-over-water tank without a membrane, it happens gradually by design: the air gradually dissolves into the water unless something replenishes it.[6] Franklin Electric's troubleshooting table lists a waterlogged tank as a cause of a motor that starts too often, and notes it can also cause nuisance tripping of the overload on some two-wire motor controls.[2]
Replace or recharge? A quick rule
| Situation | Our recommendation |
|---|---|
| Water at the air valve | Replace |
| Visible corrosion, weeping seam, bulge | Replace |
| Precharge low once, tank newer and clean | Reset per the manufacturer's instructions, then monitor |
| Precharge keeps dropping | Replace |
| Everything checks out but the pump still short cycles | Tank may be too small — see sizing |
Leave to a pro
Replacing a tank means shutting down and draining the system, handling a heavy vessel, re-plumbing the tank tee, and usually replacing the pressure switch, gauge and relief valve at the same time. Amtrol's own manual says its tanks must be installed by a licensed professional following local codes.[1]
What replacement costs
HomeGuide reports $800–$1,500 for a typical installed replacement, with a national average of $1,000; small 20–29 gallon tanks run $450–$1,000 installed and 80–99 gallon tanks $850–$2,300.[6] Size by the pump, not by household size — see how to size a well pressure tank.
Sources
- Amtrol. Well-X-Trol Residential Pre-Pressurized Well Tanks — Installation & Operation Instructions (WX-101 through WX-350). Accessed Sept. 28, 2026.
- Franklin Electric. Submersible Motors: Application, Installation & Maintenance (AIM) Manual, 60 Hz. Accessed Sept. 28, 2026.
- Water Systems Council (wellcare). Pressure Tank Pre-charge — information sheet. Accessed Sept. 28, 2026.
- Pentair. Adjusting Well Pump Pressure Switches (instruction sheet U80-129). Accessed Sept. 28, 2026.
- The Driller. How to Calculate and Control Pressure Tank Drawdown — Bob Pelikan (Feb. 1, 2006). Accessed Sept. 28, 2026.
- HomeGuide. How Much Does It Cost to Replace a Well Pressure Tank? (article dated July 25, 2025). Accessed Sept. 28, 2026.
We cite manufacturer documentation and public agencies first. Read how we choose and check sources.