Well pump pressure tank problems

The tank's own failure signature, separate from the pump's: what causes short cycling, how to tell an empty tank from a waterlogged one, and how to check its air charge.

A pressure tank problem announces itself as a pump problem: the pump seems to run too often, pressure will not hold, or nothing comes out at all. Signs your well pump is bad already separates the symptoms that point at the pump from the ones that point at the tank. This guide stays on the tank side of that split and goes a level deeper: what a lost air charge actually does inside the tank, how to tell an empty tank from a waterlogged one, and how to check the tank's air charge yourself.

What causes a well pump to short cycle?

InspectApedia's water-tank troubleshooting reference names the default cause directly: "If your water pump cycles on and off rapidly (pump short cycling) the most common cause is loss of air charge in the water pressure tank." It explains why: "A bad or defective water pressure tank which has lost its air charge or which cannot keep its air charge will cause well pump short cycling - rapid turning on and off of the water pump."

Left alone, that is not just an annoyance. The same source: "This frequent pump switching on and off is hard on the pump (damages the pump) and also on the pump switches and controls (switch contacts can become burned)." A tank problem ignored becomes a pump problem.

Source: InspectApedia, Diagnose Water Tank Problems (Daniel Friedman)

Is a pump that runs continuously the same fault?

No, and the two get mixed up often enough to be worth separating clearly. Short cycling is the tank's own signature, covered above. A pump that runs continuously and never satisfies the pressure switch is listed on signs your well pump is bad under the symptoms that point at the pump itself, not the tank. This page is only about the short-cycling side of that split.

How do I tell an empty tank from a waterlogged one?

The two failures feel different by hand, and InspectApedia states the difference directly: "waterlogged tanks are nearly full and are heavy; a light, nearly empty water pressure tank means no water is being sent into it." A gentle knock or shake is the traditional first check: "Gently moving or "shaking" the water tank can tell you if the tank contains any water at all."

That check has a real limit, and the same source is direct about it: "shaking the water pressure tank alone is not going to reliably diagnoses a ruptured bladder in a captive air water tank." A tank that shakes or sounds full is waterlogged. A tank that shakes empty only tells you it is empty, not why, and shaking alone will not tell a genuinely ruptured bladder apart from a well that simply has not refilled it yet.

It is worth doing gently. The same source: "Be careful: don't get too violent - moving a water tank around can cause plumbing leaks or even a burst pipe."

Source: InspectApedia, Diagnose Water Tank Problems (Daniel Friedman)

How do I check the tank's air charge myself?

InspectApedia's instructions start with power, before anything else: "Turn off electrical power to your water pump." Timing matters too: "to be sure that the air charge in a water pressure tank is at the proper level, always set or check the air pre-charge pressure when there is no water pressure in the system and no water pressure in the water tank." A tank checked while still under pressure will read wrong.

The target pressure, verbatim: "Add air to the water pressure tank until the tank pressure reads 2 psi below your water pressure control switch CUT-IN pressure (the pressure at which the pump will turn on)." Worked as an example: "For example if your pressure control switch is a 20/40 switch (CUT-IN at 20 psi, CUT-OUT at 40 psi) then set the tank pressure to (20 - 2) = 18 psi."

A second method skips the gauge entirely: "A simple method for recharging the air in a water pressure tank is to turn off the pump, attach a garden hose to the tank drain, open the hose, drain the tank completely, and then let the pump re-fill the tank."

Source: InspectApedia, How to Add Air to a Water Pressure Tank (Daniel Friedman)

If the air charge won't hold

A fast repeat drop is worth treating differently from a slow one. InspectApedia is direct about what it means: "If your water tank air charge is being lost rapidly, say within days of setting the proper air charge, then your water tank may have an air leak that can be fixed. Or you may need to replace the tank."

That is two different outcomes, not one, and a fixable leak is worth finding before anyone prices a new tank. If a contractor confirms it is the tank, well pump repair or replace has the published replacement range.

Source: InspectApedia, How to Add Air to a Water Pressure Tank (Daniel Friedman)

What it costs to fix, and what to do next

None of the above prices the repair. Well pump repair or replace sets the published tank and switch replacement costs against a full pump replacement and shows where each one crosses over. Well pump troubleshooting checklist turns the checks on this page into the short list a contractor, or this site's own quote form, actually asks for.