Your Autofill May Be Hiding a Leak — and Paying for It Every Month
An autofill does exactly one job: keep the water level constant no matter what. It is genuinely useful equipment through a Gulf Coast summer, when evaporation alone can pull down a quarter inch a day. But think about what “keep the level constant no matter what” means when something goes wrong. The autofill cannot tell the difference between water that evaporated and water that escaped through a cracked return line. It replaces both, silently, around the clock. The first symptom of a leak — a dropping water level — is the exact symptom the autofill exists to erase.Schedule Your Leak Detection Today
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Where the evidence goes instead
The water still has to come from somewhere, so the leak does not disappear. It just changes address, from the pool to the utility bill. That is a much worse place for it, because water bills fluctuate for ordinary reasons — a hot month, guests, more irrigation — so a gradual climb is easy to rationalize. Meanwhile the leak keeps running underground, washing soil out from under the deck the whole time. We regularly find leaks that had been running for a year or more on pools where the level never once looked wrong. The homeowner did nothing careless. Their equipment was working perfectly, doing what it was designed to do.The 48-hour test
This is the single most useful thing an autofill owner can do, and it costs nothing:- Find the autofill’s shutoff valve — usually at the equipment pad or in the autofill box itself
- Close it completely
- Mark the water level precisely with tape on the tile
- Wait 24 to 48 hours, running the pump on its normal schedule
- Measure the drop, then open the valve again
When the autofill is the leak
There is a second failure mode, and it is the one in the photo above. Inside the autofill housing is a valve, usually float operated, that opens when the level drops and closes when it recovers. It is a mechanical part sitting permanently in water. The image shows the inside of one of these housings with heavy mineral scale built up around the fill line. Scale is what our water leaves behind, and once it accumulates on the valve seat or the float arm, the valve stops closing fully. It does not fail dramatically. It just never quite shuts. Now water runs continuously. Because most installations are plumbed with an overflow to the drain line, the excess leaves quietly instead of flooding the deck. The pool looks fine. The pool is fine. The meter spins anyway.
Telling the two apart
Both problems raise the bill, but they separate quickly:- Shut the autofill off. Pool level holds steady? The autofill was the problem. Level drops? You have a real leak.
- Listen at the autofill box with the pool at normal level and everything off. A faint continuous hiss means the valve is passing water.
- Check the meter with all water in the house off and the autofill closed. Movement means something else on the property is running.
