Pool leak questions, answered

Evaporation is steady and weather-driven. On the North Carolina coast in summer it usually takes about a quarter of an inch a day, a little more in a hot, windy stretch or when the pool is heated and uncovered. A leak takes more than that, keeps taking it on cool, still days, and does not slow down when the weather does.

The bucket test settles it in 24 hours. Fill a bucket with pool water, set it on a step so the rim is above the surface, mark the water level inside the bucket and the pool level outside it, and turn the pump off. A day later, compare the two marks. If the pool dropped noticeably more than the bucket, the difference is a leak, not the weather.

If you would rather not guess, call and we will talk you through it at no charge.

A quarter of an inch a day is normal evaporation for most of the year here, and up to half an inch in a hot, dry, windy spell. Anything approaching an inch a day, day after day, is a leak until proven otherwise. Two inches a day is a leak by any measure and worth a call the same day.

Measure at the same spot on the tile line at the same time each day, with the pump off if you can, so splash-out and the pump’s own draw do not muddy the number. Heavy rain can hide a loss for a day or two; measure again once the weather settles.

Loss that shows up with the pump running and stops when it is off points to the pressure side: the return lines from the equipment pad back to the pool, and the fittings where they enter the wall. Under pressure, water is pushed out through any break. At rest, the same break sits quiet.

Air in the pump basket or bubbles from the returns can be a related sign, though that usually means the suction side is drawing air. Either way, the next step is isolating the lines and pressure-testing them one at a time rather than guessing at the yard.

Loss that continues with the equipment off is the structure itself, the suction side of the plumbing, or the fittings and penetrations: skimmer throat, returns, light niche, main drain. The pressure-side plumbing is ruled out by the pattern, which narrows the job considerably.

Watch where the level stops. A pool that drops and then holds at a particular height is telling you the leak sits at that height: the bottom of the skimmer mouth, a return fitting, the top of the light niche. If it keeps dropping with no floor in sight, the main drain, the shell or a suction line is more likely.

That the leak is at, or just above, the level where it stopped. Water cannot escape through an opening it is no longer touching. A pool that settles at the bottom of the skimmer opening usually has a leak in the skimmer body or the seal between skimmer and shell. A pool that settles around the light is often leaking through the light niche or its conduit. A pool that settles at a return fitting has a fitting or a return line leaking.

Do not let the pool drop further to find out. Refill to the normal level and call. A pool left low in coastal ground can lift or crack, and a low level puts the pump at risk of running dry.

An autofill hides the one sign everyone notices, the dropping level, by topping the pool up around the clock. The signs that remain are indirect: a water bill climbing for no reason, chemicals that will not hold because fresh water keeps diluting them, a fill valve that seems to run constantly, algae in a pool that used to behave, or wet ground and soft spots that never dry.

The check is simple: turn the autofill off for 24 hours and do the bucket test. If the pool drops more than the bucket, the autofill has been covering a leak.

A wet pad when nothing has run, drips at unions and pipe fittings, standing water under the pump, a pump that loses prime or needs priming every morning, air in the pump basket, and a filter pressure reading that has changed for no reason. Ground that stays soft or green between the pad and the pool, without rain, points to a buried line between the two.

Fittings on the pad are the easiest leaks to see and the cheapest to put right. Buried lines between pad and pool are the ones that need locating before anything is dug.

Three tools, in order. The pool’s systems are isolated and each plumbing run is pressure-tested on its own, which proves whether a line is losing and which one. Acoustic listening follows the sound of water escaping a pressurized line to a point rather than an area. Dye confirms a suspected point in the shell or at a fitting. Nothing is opened to find the leak.

You get the findings in writing: what was tested, what was ruled out and where the loss is.

Dye is heavier than water. Released slowly beside a suspected crack or fitting with the pump off and the water still, it is drawn into an opening that is passing water and drifts away from one that is not. It confirms a spot; it does not search a pool.

You can try it at a skimmer throat, a return fitting or a visible crack with a syringe and food coloring. Keep the pump off, wait for the water to go still, and hold the tip within an inch of the spot. A hit tells you something. A miss rules out only that spot.

No, and on the coast especially not. A pool is held in the ground by the weight of its water. Empty it where the water table is high and the shell can lift, crack or float. An empty vinyl liner shrinks and may not go back. And a drained pool has no water pressure to drive dye or sound, so the leak is harder to find, not easier.

Detection is done with the pool full, and most repairs are too.

Keep the pool full to its normal level and the equipment working, and note what you have seen: how fast the level drops, whether it changes when the pump runs, where the ground is wet. A pool that is clear enough to see the floor and fittings tests faster.