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A Well Pump That Short Cycles

The pump switching on and off every few seconds is the one well fault that gets worse quickly, and the cause is usually not the pump.

The short of it

Rapid on-off cycling is almost always the pressure tank rather than the pump. When the bladder fails there is no air cushion left, so the pump starts and stops within seconds. Left alone it destroys the pump, which is the expensive part of the system.

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What short cycling is

A healthy system pumps water into the tank until it reaches cut-out pressure, then rests while the tank delivers. Short cycling is when that rest period collapses to a few seconds — the pump starts, stops, and starts again, over and over, on a small draw.

Why it is usually the tank

A pressure tank works because it holds a cushion of air above a bladder or diaphragm. That cushion is what stores pressure. When the bladder fails, or the air charge is lost, the tank fills solid with water and there is nothing left to store — so pressure hits cut-out almost instantly and collapses just as fast.

A waterlogged tank feels uniformly heavy and cold rather than hollow in its upper half. That is the usual field test.

Why it matters more than it sounds

Motor wear on a pump is dominated by starts, not by running hours. A pump that starts thirty times an hour instead of twice is doing a year of starting in a fortnight. Short cycling left alone does not stay a tank problem — it becomes a pump replacement.

The other causes

A pressure switch set with too narrow a gap between cut-in and cut-out produces the same pattern. So does a leak on the delivery side that bleeds pressure back down as soon as the pump stops. Both are worth ruling out, and both cost far less to put right than a tank.

On a well, nobody else is going to notice it failing.If the pressure has gone or the pump is cycling, that is worth a call today rather than next week. We route to contractors who work on wells specifically and cover your area, matched on the ZIP code you give, and you are never charged. Nor does it have to be the well; any plumbing work is routed the same way.

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