Signs of a Bad Well Pressure Tank (and a 2 Minute Test)
The pressure tank stores water under an air cushion so your pump does not have to start every time you open a tap. When the tank fails, the pump starts working far too hard.
A bad tank is one of the most common reasons a well pump wears out early. The good news is that it is easy to test, and sometimes it only needs air.
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- The classic sign is the pump clicking on and off every few seconds when you run a tap. That is called short cycling.
- Press the air valve on top of the tank. Water coming out means the bladder has failed and the tank needs replacing.
- If only air comes out, check the air charge: it should be 2 psi below the pump cut-in, measured with the tank empty.
Is My Pressure Tank Bad? Quick Checker
Tick what matches. Then do the 2 minute tap test below.
A quick guide to narrow things down, not a diagnosis. Turn off the power before you touch any wiring.
The 6 Signs of a Bad Pressure Tank
- Rapid cycling. The pump turns on and off every few seconds while a tap runs.
- Water from the air valve. A burst bladder lets water into the air side.
- The tank sounds full all the way up. A healthy tank sounds hollow near the top.
- Pressure that pulses at the taps or in the shower.
- A clicking pressure switch and higher power bills from all the starts.
- Rust, sweating or leaks on the tank shell or fittings.
A waterlogged tank with the wrong air charge is a standard cause of a pump that starts too often, along with a bad pressure switch, a check valve stuck open or a leak (The Driller (submersible motor troubleshooting)).
The 2 Minute Test
- Open a tap and time the pump. Healthy systems run for a minute or more each start; a few seconds points to the tank.
- Press the air valve on top of the tank with a pen tip. Air is good. Water means a failed bladder.
- Knock on the tank from top to bottom. You should hear a hollow sound above the water line.
- Try to rock the tank. Very heavy for its size usually means it is full of water.
How to Check and Set the Air Charge
Bladder and diaphragm tanks come pre-charged with air, but they lose a little over time. The charge must be set with the tank empty of water.
- Switch off the pump at the breaker.
- Open a tap and drain the system until the water pressure gauge reads zero.
- Check the air valve with a tire gauge.
- Set it to 2 psi below your pump cut-in: 28 psi for a 30/50 switch, 38 psi for a 40/60 switch.
- Close the tap and switch the pump back on.
The 2 psi rule is the one tank makers such as Amtrol use. If the tank will not hold its charge for more than a few weeks, the valve or bladder is leaking.
Tire pressure gauge and small air pump
A plain dial or digital tire gauge reads the tank air valve. A small compressor or bike pump tops it up.
See options on AmazonRepair or Replace?
| What you find | What to do |
|---|---|
| Air charge low, holds after topping up | Recharge it and check again each year |
| Charge leaks away within weeks | Replace the air valve core, or the tank |
| Water from the air valve | Replace the tank |
| Rust or leaks on the shell | Replace the tank |
| Old galvanized tank with no bladder | Replace with a bladder tank |
When you replace it, size the new tank to your pump so it runs at least a minute per cycle. Use our pressure tank sizing calculator, compare picks in best well pressure tanks, and check prices in pressure tank replacement cost.
Frequently Asked Questions
How do I know if my well pressure tank is bad?
The main signs are the pump turning on and off every few seconds, water coming out of the air valve, a tank that sounds full all the way up, pulsing pressure and rust or leaks.
What should the air pressure be in my well tank?
Set it 2 psi below the pump cut-in pressure, measured with the tank drained: 28 psi for a 30/50 switch and 38 psi for a 40/60 switch.
Can a waterlogged pressure tank be fixed?
Sometimes. If the bladder is intact, draining the system and restoring the air charge fixes it. If water comes out of the air valve, the bladder has failed and the tank must be replaced.
How long do well pressure tanks last?
Many bladder tanks last about 10 to 15 years, depending on water quality, how often the pump cycles and whether the air charge is kept right.
Can a bad pressure tank damage my pump?
Yes. Constant short cycling makes the motor start far more often than it should, which shortens its life.
Sources: The Driller (submersible motor troubleshooting); tank air charge rule from Amtrol installation guidance.
