How to Check a Well Pressure Tank's Air Charge (4 Simple Steps)

TL;DR: Your well pressure tank needs the correct air charge to work efficiently. Most systems use a 30/50 PSI switch, so the tank's air charge should be 28 PSI. Check it by turning off power to the pump, draining the tank until water stops flowing, then measuring air pressure at the tank's Schrader valve with a tire gauge. Add or release air to match your cut-in pressure minus 2 PSI. A properly charged tank reduces pump cycling and prevents premature failure.

_Last reviewed: July 2026 · 6 min read_

When your well pump cycles on and off every 30 seconds, the culprit is usually a lost air charge in the pressure tank. A bladder tank relies on compressed air to push water through your home's plumbing—when that air cushion is wrong, the pump runs constantly, electricity bills climb, and the pump motor wears out years early.

Okoniq Property Hub lets you log pressure readings, track air-charge adjustments, and set reminders to recheck the tank every 12 months so you catch problems before they compound.

What does the air charge do in a well pressure tank?

A modern pressure tank has a rubber bladder inside. Water fills the bladder; compressed air surrounds it. When you open a faucet, the air pushes water out without triggering the pump—until pressure drops to the cut-in point (typically 30 PSI), which starts the pump and refills the bladder to the cut-out point (typically 50 PSI).

If the air charge is too low, the bladder expands too far and the pump cycles every time you flush a toilet. Too high and the bladder never fills properly, cutting your usable water storage in half. The correct pre-charge is always 2 PSI below your cut-in pressure. For a 30/50 switch, that's 28 PSI. For a 40/60 switch, it's 38 PSI.

You can identify your switch settings by reading the label on the square pressure switch mounted near the tank, or by watching the pressure gauge during a pump cycle. If you're troubleshooting other pump issues, how to diagnose a ceiling water stain covers similar detective work—pressure clues show up in unexpected places.

How do I measure the tank's air charge?

Turn off the circuit breaker that powers your well pump at the main panel. Open a garden hose spigot or the lowest faucet in the house and let water drain until flow stops completely—this empties the bladder so you're measuring only the air side.

Locate the air valve (a Schrader valve, identical to a car tire valve) on top or side of the tank. Unscrew the plastic cap and press a tire pressure gauge firmly onto the valve stem. Read the PSI.

Compare that number to your target: cut-in pressure minus 2. If your switch is 30/50 and the gauge shows 22 PSI, you've lost 6 PSI and the pump is short-cycling. If it shows 35 PSI, the bladder can't expand and you've lost water capacity.

Record the date and reading in Okoniq so you can spot trends—many tanks lose 2-3 PSI per year through microscopic valve leaks. When you see a pattern, you know whether to check quarterly or stick with the annual schedule.

How do I adjust the air pressure?

If pressure is low, attach an air compressor or bicycle pump to the Schrader valve and add air in 2 PSI increments, checking with the gauge between additions. Stop at your target (cut-in minus 2).

If pressure is high, press the center pin inside the valve with a small screwdriver or the reverse end of a tire gauge to release air. Check frequently—it's easy to overshoot.

Once you hit the target, replace the plastic cap to keep dirt out of the valve, close the drain faucet, and restore power to the pump. Open a faucet and watch the pressure gauge climb to cut-out, then close the faucet and listen. The pump should stay off for several minutes even with small draws like a toilet flush or washing hands.

Bladder failure (a tear in the rubber) mimics low air charge but can't be fixed by adding air—if you pump the tank to 28 PSI and it drops to 10 within an hour, or if water sprays out of the air valve when you press the pin, the bladder is ruptured and the tank needs replacement. That's a $200–400 part plus labor, versus the $0 cost of checking air pressure annually.

When should I check the air charge?

Check once a year in spring before irrigation season, when pump run-time increases and stress on the system peaks. Also check if you notice any of these symptoms:

• Pump cycles on and off rapidly (more than twice per minute during steady use)
• Water pressure fluctuates wildly between faucets
• You hear the pump run every time someone flushes a toilet
• The pressure gauge needle bounces instead of holding steady

Many landlords bundle this check with boiler maintenance basics if they have both systems, creating a single annual mechanical walk-through. If you're managing a seasonal property, add it to your closing-up checklist—a tank can lose air over the winter and you'll never know until the pump burns out in May.

Newer tanks (post-2010) hold air charge better than 1990s models, but all bladder tanks eventually lose pressure through the valve or develop pinhole leaks in the bladder itself. The 10 minutes you spend with a tire gauge now saves a $1,200 emergency pump replacement later.

FAQ

How often does a well pressure tank need the air charge adjusted?

Most tanks need adjustment every 1–3 years depending on valve quality and usage patterns. Check annually; adjust only when the reading is more than 2 PSI off target. Frequent adjustments (more than twice a year) suggest a leaking valve or failing bladder.

Can I check the air charge without draining the tank?

No. Water in the bladder compresses the air and gives a false high reading. You must drain the tank completely through a faucet before measuring. Skipping this step is the most common mistake—people see 40 PSI and think the charge is fine, when the actual air-side pressure is only 18 PSI.

What happens if I overinflate the pressure tank?

The bladder can't expand fully, so you lose water storage capacity and the pump cycles more often to maintain pressure. In extreme cases (10+ PSI over target), the bladder can rupture from being pinched against the tank wall. Always stay within 1 PSI of your target.

Why does my tank lose air charge over time?

The Schrader valve leaks microscopically, or the bladder develops tiny permeability losses. This is normal wear. Tanks in damp basements or near salt air (coastal properties) lose pressure faster. If a tank drops from 28 to 18 PSI in under six months, replace the valve core or the entire tank.

Do I need a special gauge to check well tank air pressure?

No. A standard tire pressure gauge (0–60 PSI range) works perfectly. Digital gauges are easier to read in dim basements. Avoid gauges that only read to 30 PSI—you may need to measure up to 40 PSI on some systems.

This is educational information, not plumbing or mechanical advice. If your pump short-cycles after correcting air charge, or if you're uncomfortable working with pressurized systems, call a licensed well contractor to inspect the tank, switch, and pump.