· by Michael Blair, Nashville's Pool & Spa
A dropping water level in July does not mean a leak. Evaporation in Middle Tennessee heat is substantial, and splash-out from actual swimming adds to it. Before anyone starts cutting into a deck, it is worth establishing whether the loss is more than the weather accounts for.
The bucket test
Fill a bucket with pool water and set it on a step so the water inside sits at the same level as the pool outside. Mark both levels. Leave the pump running normally for a day, then compare.
Both should fall by the same amount if the loss is evaporation, since the bucket experiences the same weather. If the pool has dropped noticeably further than the bucket, the difference is a leak. Do this with the pool not in use, since splash-out will contaminate the result entirely.
Narrowing down where
Repeat the test with the pump off for a day. A pool that loses much more with the pump running points at the pressure side, meaning the return plumbing, because it is only pressurized while the pump runs. A pool that loses more with the pump off points at the suction side or the structure.
Then check the obvious places. Wet ground or unusually green grass in one spot near the pool, a persistently damp equipment pad, air bubbles coming from the returns, or the pump losing prime. Skimmer throats are the single most common structural leak, where the plastic meets the concrete.
- Bucket test first, always, before anything else
- Compare loss with the pump running and with it off
- Check the skimmer throat and the light niche
- Look for damp ground or bright green grass near the pool
- Air in the pump basket suggests a suction-side leak
What tends to leak in a Middle Tennessee pool
Freeze damage is the local specialty. Water left in plumbing or in the equipment through a hard freeze cracks fittings, and the failure often does not show until the system is pressurized again in spring. That is why a pool that was fine in October and loses water in April usually has a winter injury.
The other pattern is movement. Expansive clay swells and shrinks seasonally, and a deck and shell that move relative to each other open the joints. Cracks in the tile line, a failed expansion joint between the deck and the coping, and skimmer separation all follow from that.
When to stop testing and call
Once you have established a real loss and narrowed it to pressure side, suction side or structure, that information makes a leak detection visit shorter and cheaper. Professionals use pressure testing on individual lines, dye at suspected structural points and listening equipment for buried plumbing.
Do not let a genuine leak run through a season. Continuously topping up means continuously adding untreated water, which fights the chemistry and costs chemicals, and water moving through soil under a deck washes out the base beneath it. That turns a plumbing repair into a deck repair.