Pressure That Surges and Drops: Reading a Well Pump and Pressure Tank
A waterlogged pressure tank looks exactly like a whole-house plumbing fault. Diagnosing at the well head first is what saves the wasted trip.
August 23, 2026 · 6 min read
Out around Caddo Mills, Nevada, and the rural parts of Hunt and Collin counties, a large share of properties are on private wells. When those homeowners call us about water pressure, the fault is on the well side more often than it is inside the house — and the two present almost identically.
What the pressure tank is doing
A well pump cannot run every time you open a tap; it would burn out in a season. So the system stores pressurised water in a tank. The tank contains a rubber bladder with compressed air on one side and water on the other. Water is pushed in until the air is compressed to the cut-out pressure, and the pump stops. As you use water, the air pushes it back out until pressure falls to the cut-in point, and the pump starts again.
That stored volume — the drawdown — is the entire reason the pump is not running constantly. Everything that goes wrong here is a variation on losing it.
Symptom: pressure surges and drops while you shower
Classic waterlogged tank. The bladder has failed or the air charge has leaked away, so there is almost no compressed air left to store energy. Drawdown collapses from many gallons to a fraction of one. The pump now cuts in and out every few seconds — short cycling — and you feel it as pressure pulsing at the shower head.
This is worth fixing quickly, because short cycling destroys pumps. Every start is hard on the motor, and a pump doing hundreds of starts an hour instead of a few will fail early and expensively.
Symptom: pressure comes and goes on its own
Suspect the pressure switch. It is a small mechanical device that senses system pressure and closes the pump contacts. The contacts pit and burn over time, and a switch with degraded contacts makes and breaks unpredictably. Water in the switch housing or a blocked sensing port produce similar behaviour.
Symptom: pressure fine at first, then falls away
This points at the well itself or the pump's capacity. If the pump is drawing down faster than the well recovers — because the water level has dropped, or the pump is worn — you get good pressure briefly and then a decline as you keep using water. A dry spell, or new development drawing on the same aquifer, can change this on a well that was stable for years.
Symptom: no water at all
- Check the breaker first. Pump circuits trip, and it is free to look.
- Check the pressure switch for burnt or welded contacts.
- Listen at the well head. A pump that hums but does not deliver is a different fault from one that is silent.
- A failed capacitor on the control box will stop a pump that is otherwise fine.
What the house side looks like instead
It is worth knowing what would point away from the well. A pressure problem at one fixture only is a fixture problem — a blocked aerator or a failing cartridge. Pressure that has fallen gradually over years across the whole house, on a property with older galvanized supply, is corrosion narrowing the pipe. A sudden house-wide loss with no well symptoms suggests a supply line failure.
The distinguishing feature of a well fault is that the pressure is not steady. Surging, cycling, or coming and going is the tank, the switch or the pump. Steady but low is usually the house.
What this does to the rest of your plumbing
Short cycling and unstable pressure are hard on more than the pump. Fixture cartridges wear faster, water heaters see pressure swings they were not designed for, and appliance inlet valves fail early. Fixing the well side often resolves a set of small annoyances inside the house that nobody had connected to it.
We work Hunt County and the rural parts of Collin and Rockwall counties as part of our normal route. Family-owned, based in Rockwall. TX Master Plumber TXM11693, TX HVAC TACLB2360E. (469) 338-5533.
Frequently asked
How do I know if my pressure tank is waterlogged?
Rock it, if it is small enough — a healthy tank feels top-heavy with air below; a waterlogged one feels solid and heavy throughout. The definitive test is at the air valve on top: with the system depressurised you should get air, and it should read a couple of psi below the pump cut-in. Water out of that valve means the bladder is gone.
Why does my well pump keep clicking on and off?
Almost always a pressure tank that has lost its air charge. Without stored air there is nothing to hold pressure between pump runs, so the pump starts and stops constantly. It should be dealt with promptly because that cycling is what kills pumps.
Can a well problem cause a high water bill?
Not directly — you are not billed for well water — but it shows on the electricity bill instead, because a short-cycling or continuously running pump draws power around the clock. An unexplained rise in electric use on a well property is worth checking at the pump.