How to Tell If Your Pool Is Leaking: The Bucket Test and Other Signs

This is the question that sends more Austin pool owners searching at midnight than any other, and it is genuinely hard to answer by eye. Our summers evaporate a serious amount of water, so a pool that seems to be dropping fast may be behaving perfectly normally, and a pool with a real leak can look like ordinary evaporation for months.

Fortunately there is a definitive test that costs nothing and takes a day.

The bucket test

The logic is simple: evaporation acts on any exposed water equally, so if you put a bucket of water next to your pool water and the pool drops faster, the difference is not evaporation.

• Fill a bucket with pool water and place it on a pool step so it is partly submerged, which keeps the bucket water at the same temperature as the pool.
• Mark the water level inside the bucket and mark the pool's water level on the outside of the bucket or on the wall.
• Leave the pool operating on its normal schedule for 24 hours. Do not swim, do not backwash, do not add water.
• Compare the two levels. If they have dropped by the same amount, that is evaporation and your pool is fine. If the pool level has dropped more than the bucket level, you have a leak.
• Run it again with the pump switched off for 24 hours. If the loss is worse with the pump running, the leak is likely in the pressure-side plumbing. If it leaks the same either way, suspect the shell, the skimmer, or a fitting.

How much loss is normal in Austin?

As a working rule, a quarter of an inch a day is normal summer evaporation for an Austin pool, and a hot, dry, windy day can push it higher. That works out to roughly an inch and a half to two inches a week.

Losing half an inch or more a day, consistently, points to a leak. So does losing more than about two inches a week when the weather has not been extreme. And any pool where the autofill valve now runs constantly, when it used to cycle occasionally, is telling you something changed.

Two factors inflate normal evaporation and confuse the picture: wind, which strips water from the surface far faster than still air, and a heated pool, which evaporates much more than a cold one. If you have just started running the heater, expect the loss to jump for reasons that have nothing to do with a leak.

The other signs of a leak

• The autofill valve runs constantly, or the water bill has climbed with no other explanation.
• Persistently wet, soft, or spongy ground near the pool, the equipment pad, or along the line between them, even when it has not rained.
• Soil settling or sinking near the shell, or new cracks appearing in the deck and coping. In Central Texas clay this is both a symptom of a leak and a consequence of one.
• Air bubbles blowing from the return jets, which means air is being drawn into the system. That is a suction-side leak, usually before the pump.
• Chemistry that never holds. A pool that constantly needs chemicals topped up may be quietly diluting itself through a leak-and-refill cycle.
• A visible crack in the plaster, or grout missing around the skimmer throat, which is one of the most common leak points of all.

Narrowing down where it is

Once you know there is a leak, a few checks help before you call anyone. Turn the pump off for a day and see where the water stops dropping, because the water level often settles at the height of the leak. If it stops at the skimmer, suspect the skimmer. If it stops at the light, suspect the light niche. If it drains well below every fitting, suspect the shell or main drain.

Dye testing is the DIY method for confirming a suspected crack. With the pump off and the water perfectly still, release a small amount of leak-detection dye or food coloring right next to the suspected spot. If water is escaping there, the dye is drawn into the crack in a visible thread.

What you should not do is start cutting decking or excavating on a hunch. Underground plumbing leaks are located properly with pressure testing and electronic listening equipment, and a $300 to $600 diagnostic is drastically cheaper than opening the wrong section of concrete.

Why it matters more in Central Texas

A leaking pool anywhere wastes water and chemicals. A leaking pool in Austin does something worse: it keeps a patch of expansive clay soil permanently saturated.

That soil swells when wet and shrinks when it dries, and it exerts real force on whatever is next to it. Sustained over months, that movement cracks decking, settles the ground around the shell, and in serious cases stresses the pool structure itself. If the leak is close to the house, saturated soil against a foundation is a genuinely expensive Austin problem.

This is why a leak is worth chasing even when the water loss seems tolerable. The repair is rarely urgent in week one. It is often much more expensive in year two.