Pressure Tank Troubleshooting: The Sheet That Says Replace a Waterlogged Tank

By SubcontractorHub Editorial Team·Published November 2026

Sizing a new tank from pump flow is a calculator. This page is the troubleshooting publication, fetched in full. It does not add causes the PDF does not list, and it does not price a tank. Drawdown for a replacement you have already decided to buy is the pressure tank sizing calculator. Demand is from a public search only. Ahrefs was not refreshed.

What Pressure Tank Troubleshooting Is For

Department of Health publication 331-342, revised September 2017 and fetched the day this was written, describes a bladder pressure tank as a vessel with pressurized air and water separated by a membrane, pre-charged with air at the factory. It says that, on average, a bladder pressure tank lasts 5 to 7 years. That average is not a promise that the tank in front of you will fail on year six. It is the sentence on the sheet.

The functions it lists are to hold a desired pressure range, to minimize pump cycling because frequent starts and stops can damage facilities, and to protect against water hammer. It also says bladder pressure tanks do not provide any actual useful water storage capacity. Read that as the sheet's contrast with a storage tank you can draw down for a long outage, not as a claim that the bladder does nothing between cut-in and cut-out. The sizing calculator is where drawdown gallons are worked.

The cycle drawing on the PDF uses two common ranges, 30 to 50 psi and 40 to 60 psi. Pump off when the tank is nearly empty and the air is at the pre-charge. Pump starts as water compresses the air. Pump stops at the cut-off. Demand lets the air push water out and the cycle repeats. Pressure tank troubleshooting starts when that cycle collapses into rapid clicking.

When the Sheet Says the Tank Is Waterlogged

331-342 says a tank is waterlogged when the internal bladder fails and water fills the air space around the bladder. The instruction is to replace waterlogged tanks. The signs it lists are specific. Gently tipping the tank may show the problem by weight. The pump motor cycles on and off rapidly. A tap on the shell sounds different from a tank with a normal air-water balance. When you depress the pin of the air-charging valve, water escapes. Stale, rusty water at the tap can come from corrosion inside the tank. The helpful hint says it is often most cost-efficient to replace a waterlogged tank.

Water at the air valve is the sign this page will not talk a customer out of. Recharging air into a tank that is already passing water through the valve is not the repair the sheet describes. Say "replace" and then size the next tank on the calculator, from the pump's gallons per minute and the switch, not from the old shell's faded label alone.

The Air Check in That Pressure Tank Troubleshooting Sheet

Air leaves a bladder tank the way it leaves a tire, the sheet says. Loss of air over-expands the bladder and can fail it early. Loss of air also leads to excessive pump cycling, which may shorten the life of the well pump motor. The hint is to follow the manufacturer if you can do it safely, and otherwise to hire someone. It says to take safety seriously and not to exceed your experience.

The typical steps, which the PDF labels as typical manufacturer instructions rather than a universal code, are these. Turn the pump power off or isolate the tank. Open a faucet and drain the tank completely. Check air pressure at the valve on top with a gauge. The air pressure should be 2 psi below the start pressure setting of the pump. Use a compressor to charge it. Do not over-pressurize. Close the faucet. Turn power back on or open the isolation valve and refill. Confirm the pump turns on and off at the right pressures on the system gauges.

On a 30 psi start, 2 psi below is 28 psi. On a 40 psi start, it is 38 psi. Those two figures are arithmetic from the sheet's "2 psi below" line and the ranges drawn on the page. They are not a new rule. If the nameplate start pressure is different, use that start pressure minus 2 psi, still only when the tank is empty of water.

The Warning About Opening the System

The same section tells the reader to avoid depressurizing the water system. It says depressurizing creates a high risk of backflow and contamination, and it tells public-water operators to contact their regional office before they depressurize as part of an air adjustment or other work on the tank. Tank condition, gauge accuracy, and the pressure-relief valve can make the job hazardous. The sheet points to a companion note, 331-429, on pressure relief valves. That second PDF was not fetched, so its design rules are not copied here.

A house on a private well is not the audience written at the top of a drinking-water tech tip for public systems, but the mechanical signs are the same bladder. The backflow warning is quoted because it is on the page, not because this article is a cross-connection manual. If you are on a public system, the sheet's instruction is to call the region first. The after-hours number printed on 331-342 is 877-481-4901.

How to Log Pressure Tank Troubleshooting

1. Write whether water came out of the air valve. If it did, the sheet says replace.
2. If it did not, write the air pressure you read and the pump start setting, so the 2 psi gap is visible.
3. Write that the tank was drained before the reading. A gauge on a tank still full of water is not the step in the PDF.
4. Write the cut-in and cut-out you saw after power was restored.
5. Do not add a check-valve diagnosis this PDF does not contain. If you suspect one, say it is not from 331-342.
6. Do not write a tank price. None is on the sheet.

If the tank is replaced, size the next one from flow and the switch on the pressure tank sizing calculator. The pump that fills it is the well pump size calculator. Whether the well can keep up with treatment backwash is the well recovery rate calculator. A UV chamber downstream of this tank has its own lamp interval on UV lamp replacement.

Public search also returned contractor blogs about short cycling from a bad check valve or a leak. Those pages were not the publication fetched in full, so they are not folded into this list. One sheet, one set of signs. If the bladder is intact, the air is 2 psi under start, and the pump still short-cycles, this PDF has finished its job and the next test is outside it.

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