Pump Short-Cycling? It's Often the Tank.

Pressure Tank Service in Elbert County

The pressure tank is the quiet workhorse of your well system, and when it fails it takes the pump down with it. Its job is to hold a cushion of pressurized air against a volume of water so your pump isn't forced to start every single time you open a faucet. When the tank loses that air cushion, the pump cycles on and off rapidly — and that “short-cycling” is the number-one cause of premature pump burnout. The frustrating part is that a failing tank rarely announces itself as a tank problem. It shows up as pulsing water, a pump that never seems to rest, or a motor that dies years before it should — so the smart move is to diagnose the tank as part of the whole system before spending money on the wrong part.

How a pressure tank actually works

Understanding what's happening inside the tank makes every symptom make sense. A well pump doesn't push water straight to your tap on demand — it fills a tank, and the tank feeds the house between pump cycles. Modern tanks are diaphragm (or bladder) tanks: a flexible rubber membrane separates a pre-charged air chamber from the water. As the pump runs, water fills the tank and compresses the air on the other side of the membrane. When you open a faucet, that compressed air pushes the stored water back out — so the pump can stay off until the tank draws down to the point where it needs to kick on and refill. The air side is pre-charged to about 2 psi below the pump cut-in pressure. For a common 40/60 switch, that's roughly 38 psi in the tank measured with the water side drained; for a 30/50 switch it's about 28 psi. That air charge is the heart of the whole arrangement — get it wrong and the tank can't do its job.

The amount of water the tank actually delivers between the pump shutting off and kicking back on is called drawdown. It's always a fraction of the tank's total volume — a “44-gallon” tank might only give you ten or twelve gallons of usable drawdown — because the air cushion has to keep the pressure up as the water leaves. Proper drawdown is what keeps the pump from starting too often, which is exactly why a tank that has lost its air charge is so hard on a pump.

Types of pressure tanks

Not every tank is built the same, and the type on your system changes how it fails and how it gets serviced:

• Diaphragm tanks — a fixed rubber diaphragm sits across the middle of the tank, air above, water below. Common, reliable, and the standard on most newer installs.
• Bladder tanks — the water is held inside a replaceable balloon-like bladder while the air fills the space around it, so the water never touches the steel shell. This keeps the tank interior from corroding and is a popular long-life design.
• Older air-over-water (plain steel) tanks — the oldest style has no membrane at all; air and water share the same space. Over time the air simply dissolves into the water and the tank becomes waterlogged, which is why these older tanks needed periodic recharging or an air-volume control to add air back. If you've got one of these, short-cycling is almost expected without regular attention.

Signs of a waterlogged or failing tank

How a tank problem gets diagnosed

A methodical check confirms it's really the tank before anything gets replaced, because short-cycling can also come from a bad pressure switch or a clogged sensing port. A pro will typically:

• Watch the gauge while water runs — the pattern of how fast the pressure rises and falls, and how often the pump cycles, points straight at drawdown loss.
• Check the air pre-charge with the tank drained — the air pressure is only meaningful with the water side emptied. Reading it against the pump's cut-in setting shows whether the charge is simply low or the membrane is gone.
• Test the air valve for water — water coming out of the Schrader valve is the definitive sign of a ruptured diaphragm or bladder.
• Confirm the pressure switch settings — verifying the cut-in and cut-out numbers rules the switch in or out, so a new tank isn't asked to fix a switch problem.

Recharge, or replace?

Sometimes a tank has simply lost air pressure and can be re-charged to spec — a quick, inexpensive fix, especially on older air-over-water tanks that lose air naturally over time. But on a diaphragm or bladder tank, once the internal membrane has ruptured (water on the air side), the tank is done and needs replacing; there's no recharging a torn bladder. A rusted-through or leaking shell is likewise a replacement. The honest test is to check the pre-charge, check the membrane, and confirm the pressure switch is set correctly — so a new or recharged tank actually solves the problem instead of masking it. When a tank does get replaced, matching the drawdown to the household's water use and the pump's start rating is what keeps the new tank from short-cycling all over again.

What drives the cost of a pressure tank job

There's no single sticker price, because the right fix depends on what actually failed and what the system needs:

• Recharge vs. replacement — simply adding air back to a tank that only lost its charge is a far smaller job than swapping the tank out.
• Tank size — a larger tank with more drawdown costs more than a small one, but the right size reduces pump cycling and can pay for itself in pump life.
• Tank type — a basic diaphragm tank and a long-life bladder tank sit at different price points.
• What else gets renewed — it often makes sense to replace an aging pressure switch, a corroded tank tee, or worn fittings while the system is already opened up, rather than paying twice.

The point of diagnosing first is simple: you only pay for the parts and labor the well actually needs, and you protect the pump — the most expensive piece of the whole system — in the process.