How to Check and Set Pressure Tank Air Charge

Every bladder-style pressure tank has a sealed air chamber that needs to hold a specific pressure — called the precharge — to work correctly. Over months and years, that air charge slowly leaks out, and when it does, the tank starts waterlogging: it fills almost entirely with water, the air cushion disappears, and your pump starts short-cycling. Checking and correcting the precharge is a 10-minute job that requires nothing more than a tire pressure gauge and an air pump.

Step 1: Kill the Power and Drain the Tank

Shut off power to the well pump at the breaker. Open a faucet somewhere in the house and let it run until pressure drops to zero — you'll hear the water stop and see the pressure gauge on the tank (if it has one) fall to 0 psi.

Step 2: Find the Air Valve

Look for a Schrader valve — it looks exactly like the valve stem on a car tire — usually on the top of the tank. Remove the cap.

Step 3: Check the Pressure With a Tire Gauge

Press a standard tire gauge onto the valve just like you would on a car tire. The reading should be 2 psi below your pump's cut-in pressure. If your pressure switch is set to 40/60 (cut-in at 40, cut-out at 60), your tank precharge should read 38 psi.

Step 4: Add or Release Air as Needed

If the reading is low, add air with a bike pump, compressor, or shop air until it hits the target. If it's too high (rare, but possible after a repair), press the valve pin briefly to release a little air. Recheck after every adjustment — it's easy to overshoot.

Step 5: Restore Power and Check for Leaks

Turn the breaker back on and let the system refill and cycle normally. If the tank loses precharge again within a few weeks, the bladder itself likely has a leak, and no amount of re-pressurizing will fix it — that points to tank replacement rather than a maintenance issue.