Your pressure tank has one job: store pressurized water so your pump doesn't have to start every time someone rinses a glass. When the tank fails, the pump starts doing exactly that — cycling on and off dozens of times an hour — and every cycle is a hammer blow to the most expensive component in your water system.
The diagnosis takes two minutes and a $5 tire gauge. Here's the whole troubleshooting tree.
How the Tank Works (30 Seconds)
Modern tanks are bladder or diaphragm tanks: a balloon of compressed air on top squeezes water out of the bottom. Air charge pushes water out until pressure falls to the pressure switch's cut-in (typically 30 or 40 psi), pump refills the tank until cut-out (50 or 60 psi), repeat. The air charge is the spring in the whole mechanism. Lose the air, and the tank is just a steel jug full of water — "waterlogged" — with no capacity to buffer anything.
The Symptoms
- Short cycling: pump clicks on/off every few seconds during water use. The signature symptom of a waterlogged tank.
- Pressure that pulses at the shower head, on/off/on/off.
- The tank feels heavy and full at the top. Push the tank near the top: a healthy tank rocks easily and sounds hollow up top. Knock on it: hollow ring above, dull thud below the water line. Thud all the way up = waterlogged.
- Water spits from the air valve. Press the Schrader valve (looks exactly like a tire valve) on top of the tank; if water comes out, the bladder is ruptured — skip straight to replacement.
The 2-Minute Air Charge Check
You need a tire-style pressure gauge and your pressure switch's cut-in number (look at the switch cover: "30/50" or "40/60" — first number is cut-in).
- Kill power to the pump at the breaker.
- Drain the tank: open a low faucet or the tank's drain valve until water stops flowing and pressure hits zero.
- Gauge the Schrader valve on top of the tank.
The rule: air charge should be 2 psi below cut-in. A 40/60 system wants 38 psi in an empty tank; a 30/50 system wants 28 psi.
- Reading correct (within a couple psi): Tank's fine — your short cycling is elsewhere: a stuck pressure switch, a clogged switch sensing tube, or a leak.
- Reading low, no water at valve: Recharge with a bicycle pump or compressor to cut-in minus 2. Restore power, run the system, recheck in a week or two. Slow loss over months = normal maintenance (air diffuses); loss in days = leaking valve core or pinholed bladder.
- Water at the valve: Bladder's ruptured. Replace the tank — air recharges will only buy days.
Replacing the Tank
A ruptured bladder isn't repairable. The good news: a replacement pressure tank is $150–$400 and swapping one is honest DIY: kill pump power, drain, unscrew the old tank from the tank tee, thread on the new one with fresh PTFE tape, pre-check its air charge before filling, repressurize, check for leaks.
Two buying notes:
- Bigger is better for pump life. Tank size determines drawdown — how much water flows between pump cycles. A pump should run at least 60 seconds per cycle; if your old tank was small and your pump short-cycled even when healthy, upsizing is the cheapest pump-longevity upgrade available.
- Match the connection size (usually 1" or 1¼") and don't reuse a corroded tank tee — replace it and the gauge while everything's apart; they're a few dollars.
Old-style galvanized (bladderless) tanks that waterlog every few months: an air volume control can maintain them, but a modern bladder tank ends the ritual permanently.
Your Action Plan
- Now: Find your cut-in number, do the knock test.
- This weekend: Kill power, drain, gauge the air charge. Recharge to cut-in minus 2 if low.
- If water exits the air valve: order the replacement tank.
- Every 6 months forever: repeat the 2-minute check. Air loss is normal and gradual — catching it early is the difference between a bike-pump fix and a pump replacement.
That 6-month recheck is the part everyone intends and nobody does. Log today's air charge reading in the WellKept app and set the recurring reminder — next time it fires, you'll also see what the charge was last time, which tells you the loss rate, which tells you whether the tank is aging normally or failing. Two numbers with dates beat a perfect memory.
Frequently Asked Questions
How do I know if my pressure tank is waterlogged? Knock down the side of the tank: it should sound hollow on top and dull at the bottom. Dull the whole way up, plus a pump that clicks on and off rapidly during water use, means waterlogged. Confirm by pressing the air valve on top — water spraying out means the bladder is ruptured.
What should the air pressure be in a well pressure tank? Two psi below your pressure switch's cut-in setting, measured with the pump off and the tank completely drained of water. A 40/60 switch wants 38 psi; a 30/50 switch wants 28 psi. Checking with water in the tank gives a meaningless reading.
Why does my well pump turn on every time I use water? The pressure tank has lost its air charge or its bladder has failed, so it stores almost no usable water. Every small draw drops pressure instantly to cut-in and starts the pump. Recharge the air or replace the tank — rapid cycling wears out pumps and switches fast.
How long do well pressure tanks last? Diaphragm and bladder tanks typically last 7–15 years. Correct air charge is the biggest lifespan factor — a tank run waterlogged flexes its bladder far more per gallon delivered. The twice-yearly air check is what gets you to the long end of the range.
Can I add air to my pressure tank myself? Yes. Turn off the pump breaker, drain the tank to zero pressure through a faucet or drain valve, then add air through the Schrader valve on top with a bicycle pump or compressor until the gauge reads cut-in minus 2 psi. Restore power. It's a tire-inflation job, nothing more.