How to Test a Pressure Tank

What You Need

A standard tire pressure gauge. That's it. No special tools required.

Test 1: The Schrader Valve Test (Bladder Check)

1. Turn the pump OFF at the breaker.
2. Open a faucet and let all pressure release until water stops flowing.
3. Find the Schrader valve on the tank (top or side — looks like a tire valve).
4. Press the center pin briefly with a screwdriver tip.

Result — Air comes out: Bladder is likely intact. Proceed to Test 2.

Result — Water comes out: Bladder has failed. Tank is waterlogged. Replace the tank.

Result — Nothing comes out: Tank has lost all pre-charge air. Proceed to Test 2.

Test 2: Pre-Charge Pressure Check

With the pump still OFF and system pressure at zero, press your tire gauge against the Schrader valve. Read the pressure.

Correct pre-charge: 2 PSI below your cut-in pressure. For a 30/50 switch: 28 PSI. For a 40/60 switch: 38 PSI.

If pressure is low, add air using a bike pump or air compressor. If it won't hold air, the bladder is failing.

Test 3: The Drawdown Test (Sizing Check)

1. Let the pump build pressure to cut-off and shut off.
2. Open a faucet and count the seconds until the pump starts again.

Under 30 seconds: Tank is undersized or waterlogged — insufficient drawdown.

60–120 seconds: Normal for most residential systems.

Over 2 minutes: Well-sized tank in good condition.

Frequently Asked Questions

What tools do I need to test a pressure tank?

A tire pressure gauge (or pump with a built-in gauge) is the main tool — the same kind you'd use on a car tire. You'll also want a bucket and stopwatch for a drawdown test, and access to the tank's air valve, which is usually a Schrader valve like on a tire, located on top of the tank.

How often should I test my pressure tank?

Check the air pre-charge once a year as routine maintenance. Test sooner if you notice short-cycling, fluctuating pressure, water hammer, or a drop in water pressure throughout the house — these symptoms usually mean the tank needs testing right away, not at the next scheduled check.

What pressure reading means my tank has failed?

Water coming out of the air valve when you press it means the bladder has ruptured — that's a failed tank, not something you can recharge. If only air comes out but the reading is far below 2 PSI under your switch's cut-in setting, the tank likely just needs to be recharged, not replaced.

Can I test the tank without draining the whole system?

The Schrader valve and pre-charge checks don't require draining — you check air pressure with the tank empty of water but the system otherwise intact (pump off, no water flowing). A full drawdown test does require running water until the pump kicks on, so plan to be without water briefly during that test.

What's a normal drawdown amount for my tank size?

Drawdown (the usable water volume before the pump kicks back on) is typically 30-40% of a tank's total volume for a properly sized and charged tank — for example, a 40-gallon tank should give roughly 12-16 gallons of drawdown. Significantly less suggests low pre-charge or an undersized tank.