Every pool loses some water — that’s normal. Evaporation, splashing, and backwashing all take their toll. But when the water level keeps dropping faster than it should, something else might be going on. Knowing how to tell the difference between natural water loss and an actual leak can save you from costly pool repair down the road.
Is It Evaporation or a Leak?
This is the first question every pool owner should ask. Evaporation rates vary depending on heat, wind, humidity, and sun exposure. During hot summer months, it’s not unusual to lose water — but anything beyond that warrants a closer look.
The simplest way to check is the bucket test.
How to do it:
- Fill a bucket with pool water and place it on a pool step (so it’s partially submerged)
- Mark the water level inside the bucket and the pool water level on the outside
- Wait 24–48 hours without running the pump
- Compare the two levels
If the pool has lost significantly more water than the bucket, you likely have a leak — not just evaporation.
Common Signs Your Pool Is Leaking
Sometimes a leak announces itself clearly. Other times, it hides in plain sight. Watch for these warning signs:
- Unexplained drop in water level beyond what evaporation explains
- Wet or soggy ground around the pool equipment, plumbing lines, or pool deck
- Cracks or gaps in the pool shell, tile, or coping
- Higher-than-normal water bills if your pool refills automatically
- Air in the pump or the pump losing prime frequently
- Loose or shifting pool deck sections, which can indicate water eroding the ground beneath
None of these signs on their own guarantee a leak, but a combination of them is a strong signal that something needs attention.
Where Leaks Commonly Occur
Pool leaks tend to show up in a handful of predictable places. Knowing where to look narrows things down quickly.
The shell — Gunite, fiberglass, and vinyl pools can all develop cracks or gaps over time, especially after ground movement or extreme temperature changes.
Plumbing lines — Underground pipes can crack, separate at joints, or corrode. These are among the trickier leaks to locate without professional equipment.
Fittings and returns — The points where water enters and exits the pool are common leak spots. Gaskets wear out, fittings loosen, and seals deteriorate.
The pump and filter system — Equipment leaks often appear around the pump housing, filter tank, or valve connections. These are usually visible and easier to address early.
Lights and skimmers — The conduit behind pool lights and the skimmer body itself can crack, especially in older pools.
When to Call a Professional
Some leaks are DIY-friendly — a cracked skimmer or a loose fitting can sometimes be patched with the right materials. But many leaks require pressure testing, dye testing, or specialized listening equipment to locate precisely.
If you’ve done the bucket test, spotted some warning signs, but can’t pinpoint the source, it’s time to bring in a pool repair professional. Chasing an underground plumbing leak without the right tools usually means more digging and more expense than necessary.
Catching a leak early is almost always cheaper than dealing with the damage caused by prolonged water loss — including eroded soil, foundation shifting, and equipment strain.
Stay Ahead of the Problem
Check your water level consistently. Do the bucket test at the first sign of unusual loss. And don’t ignore wet spots or rising utility bills. A small leak left unaddressed has a way of becoming a much bigger problem. The earlier you act, the simpler — and less expensive — the fix tends to be.