Well pressure tank problems: short cycling, waterlogged tanks and how to check the air charge

How a well pressure tank works, the signs it's failing, how to check and set the air precharge, what a waterlogged tank means, and when to call a well contractor.

By the Septic & Well Guide editorial team · Last reviewed October 4, 2026 · How we research

If your house is on a private well, the pressure tank is the part of the system you can actually see, usually a blue, gray or white tank in the basement, garage or well house. It's also one of the most common reasons a well system acts up. The good news: the most frequent pressure tank problem can be diagnosed in ten minutes with a tire gauge. This guide explains how the tank works, the symptoms of trouble, and how to check it.

What the pressure tank does

A well pump can't run every time someone opens a faucet. Starting a pump motor draws a surge of current and wears the motor, so the system needs a buffer. That's the pressure tank.

Most modern tanks have a rubber bladder or diaphragm that separates water from a cushion of compressed air. Here's the cycle:

The pump runs and pushes water into the tank, squeezing the air.
When pressure reaches the cut-out setting on the pressure switch (often 50 or 60 psi), the pump shuts off.
As you use water, the compressed air pushes water out to the faucets, and pressure falls.
When pressure drops to the cut-in setting (often 30 or 40 psi), the pump starts again.

A pressure switch labeled 30/50 or 40/60 tells you those two numbers. The amount of water the tank delivers between pump starts is called the drawdown. A healthy tank lets the pump run less often and for longer cycles, which is what pump motors are designed for.

Our guide to how private wells work explains the rest of the system, from the pump to the faucet.

Signs of a pressure tank problem

Short cycling. The pump clicks on and off every few seconds while water runs, or the pressure gauge needle swings rapidly between cut-in and cut-out. This is the classic sign.
Pressure that swings noticeably at the shower while someone else uses water.
A pause in water flow before the pump kicks in, then a surge.
The tank sounds or feels full of water all the way to the top when you knock on it, instead of hollow near the top.
Water from the air valve. If water comes out of the tire-style valve on top of the tank, the bladder has failed.
Higher electric bills or a pump that fails early.

Short cycling matters because repeated starts are hard on the pump motor and the pressure switch contacts. A tank problem left alone can turn into a much more expensive pump replacement.

The air precharge: what it should be

The air side of a bladder tank is filled at the factory to a set pressure, called the precharge. AMTROL, one of the largest well tank makers, says its well tanks ship with a standard precharge of 38 psi.

The precharge needs to match your pressure switch. AMTROL's installation instructions say to release or add air so the precharge is 2 psi below the pump's cut-in setting. Its example: with a 30/50 pressure switch, adjust the precharge from 38 psi down to 28 psi. By the same rule, a 40/60 switch calls for 38 psi, and a 20/40 switch for 18 psi.

Why 2 psi below? The bladder should be nearly empty, but not completely empty, at the moment the pump starts. If the precharge is too low, the tank holds less usable water and the pump cycles more. If it's higher than the cut-in pressure, the tank runs out of water before the pump starts, which causes a momentary loss of flow.

Boshart Industries, which makes pressure switches and well fittings, notes that temperature changes affect the air charge just as they do a car tire. A tank charged in a cold basement in winter can read a few psi higher in summer, enough to close a 2 psi margin. Boshart mentions guidance of 10 to 20 percent below cut-in and suggests about 15 percent if you see this problem. Follow your tank manufacturer's instructions first.

How to check the precharge

You need a standard tire pressure gauge, ideally a digital one that reads accurately in the 20 to 60 psi range, and a bike pump or small compressor.

Turn off power to the pump at its breaker or disconnect. This is important: you're going to drain the system.
Drain the tank. Open a faucet or the drain valve near the tank, and let water run until it stops and the system pressure gauge reads zero. AMTROL's instructions say to drain the tank of all water before checking precharge. A reading taken with water in the tank shows system pressure, not the air charge.
Remove the cap on the air valve, usually on top of the tank.
Check the pressure with the gauge.
Press the valve stem briefly. If air comes out, the bladder is intact. If water comes out, the bladder has failed and the tank needs replacement.
Adjust. Add air with the pump or let some out until the precharge is 2 psi below the cut-in pressure (or your tank maker's figure).
Close the faucet, restore power, and watch the pump fill the tank to cut-out. Then open a faucet and confirm the pump runs for a longer, steadier cycle.

AMTROL's instructions also caution against overcharging. Never exceed the tank's maximum working pressure on its label.

What the results mean

Precharge low, but air comes out of the valve: the tank just needed air. Bladders slowly lose a little air over time. Recheck it in a few months. If it keeps dropping quickly, there may be a slow leak at the valve or in the bladder.
Precharge near zero and water comes out of the valve: the bladder or diaphragm has ruptured and the tank is waterlogged. Adding air won't help for long. The tank should be replaced.
Precharge correct, but the pump still short-cycles: the tank probably isn't the problem. Common other causes are a failing check valve (pressure drops even when no water is being used), a leak somewhere in the plumbing, a faulty pressure switch, or a tank that's too small for the pump. These are jobs for a well contractor.

Older tanks without a bladder

Some older homes have a plain steel tank with no bladder, where air and water are in direct contact. Air slowly dissolves into the water, so these tanks become waterlogged over time and need to be drained and recharged periodically, or fitted with an air volume control. If you have one and it gives you constant trouble, a modern bladder tank is usually a worthwhile upgrade.

Signs the tank should be replaced

water from the air valve;
rust, pinhole leaks or a wet base;
a precharge that won't hold even after adding air;
a tank so old that the pump keeps short-cycling despite a correct precharge.

Pressure tanks are heavy when full and connect to the well's electrical controls, so many owners hire a well contractor or plumber to replace them. If you do it yourself, turn off the pump's power, relieve all pressure, and set the new tank's precharge before filling it.

Keep it working

Check the precharge once a year, using the steps above.
Look at the pressure gauge occasionally while water runs. You'll learn what "normal" looks like.
Keep the area around the tank dry and accessible.
If you have a water treatment system, ask the installer whether it affects the tank's location or pressure settings.