Is your pool losing water to the heat, or to a leak?

What normal evaporation looks like around Jackson

Evaporation is driven by heat, wind, and dry air pulling moisture off the water surface, the same process the U.S. Geological Survey’s Water Science School describes for lakes and reservoirs. A backyard pool is a small lake, and a Jackson summer works it hard. Per the National Weather Service’s Jackson climate records, July and August highs here average in the low 90s, and late summer often brings week-long dry stretches where the sun sits on the pool all day.

In that kind of weather, a pool in the metro typically loses an eighth to a quarter inch of water a day. A hot, breezy week after a dry front can push it toward a half inch, and a spa spillover or waterfall adds more because moving water sheds moisture faster than still water. So a quarter inch a day in August is nothing to worry about. An inch a day is not evaporation. No weather in Mississippi takes an inch off a pool daily.

The bucket test settles it in 24 hours

You don’t need us to tell you whether the loss is weather or a leak. A five gallon bucket answers it:

1. Set the bucket on the second step of the pool and put a rock or brick in it so it stays put.
2. Fill the bucket so the water inside sits at the same height as the pool water outside it.
3. Mark both levels with a grease pencil or a strip of tape.
4. Run the pool on its normal schedule and stay out of it for 24 hours.
5. Compare the two marks.

The bucket and the pool sit in the same sun, the same wind, and the same humidity, so they evaporate at the same rate. If both levels dropped the same amount, the pool is only losing water to the air. If the pool dropped noticeably more than the bucket, the difference is going somewhere it shouldn’t.

Run it twice to learn where the leak is

If the first test shows a leak, run it again with the pump off for 24 hours. Comparing the two runs narrows down the problem before anyone picks up a wrench:

• Loses more with the pump running. The leak is likely on the pressure side of the plumbing, the pipes that carry water back to the returns. Pressure forces water out of any gap, so the loss speeds up when the pump is on.
• Loses more with the pump off. Points to the suction side or to the shell itself, since running the pump keeps suction lines under vacuum instead of letting them drain.
• Loses the same either way. Usually a shell problem: a crack, a loose fitting, the skimmer throat, or the light niche.
• The level stops dropping at one spot. That’s the most useful clue of all. Water only escapes through openings below the surface, so if the pool stabilizes an inch below the skimmer, look at the skimmer. If it stabilizes at the returns, look there.

Where gunite pools in this metro usually leak

After enough repairs around Jackson you see the same culprits over and over, and most of them trace back to the ground. Much of the metro sits on Yazoo clay, which swells when it’s wet and shrinks hard in a dry August. The pool shell, the deck, and the buried plumbing all move a little differently as the clay works, and the weak points give first. The usual suspects:

• The skimmer throat. The skimmer is cast into the deck while the pool is its own structure. When clay movement shifts one relative to the other, the joint between skimmer and shell opens up. This is the single most common leak we find.
• Structural cracks. Soil movement can crack a gunite shell, usually diagonally from a corner or through the bond beam. Below the waterline, those cracks weep constantly. How we fix them is on our crack repair page.
• Underground plumbing. Rigid pipe in moving clay eventually separates at a fitting. These leaks hide completely out of sight and can run for a long time before anyone notices.
• The light niche. The conduit that carries the light cord is a straight path out of the pool if its seal fails.
• An old liner over a gunite shell. Some older metro pools wear a vinyl liner dropped into the concrete years ago, and aged vinyl leaks through pinholes and seams. Those owners are usually pricing vinyl liner replacement in Jackson when the better long-term fix is often resurfacing the gunite underneath.

One thing worth repeating: finding any of these does not require draining the pool. Dye testing, pressure testing the lines, and listening equipment all work with the pool full, which is how we do it. The full process is on our leak detection page, and what a leak inspection includes and costs walks through the visit step by step.

Why waiting on a leak costs more here than most places

The water itself is the small cost. A leak losing a quarter inch a day beyond evaporation on a typical 450 square foot pool is roughly 70 gallons a day, call it 2,000 gallons a month, plus the chemicals and heat that leave with it. The bigger problem is where that water goes. A steady leak feeds the clay under and around the shell, and saturated Yazoo clay swells, then shrinks when it finally dries. That cycle is exactly what cracks shells and shears plumbing, so a small leak left alone tends to create the bigger repair it eventually becomes. Typical prices for leak detection, crack injection, and plumbing repairs are published on our cost guide, no phone call required.

The short version: measure before you worry. If the bucket says evaporation, top the pool off and enjoy the rest of the summer. If the bucket says leak, the sooner it’s found, the smaller the fix.