Domakihub How to Find a Pool Leak Before It Costs You
Step-by-step methods to confirm a leak and pinpoint exactly where it is.
Reviewed by Domakihub pool pros · 2026-06-23 · 5 min read
A pool that loses water every day costs you money in refills, chemicals, and—eventually—structural damage to the surround or building. In Greece's hot climate, it can be hard to tell the difference between normal evaporation and a genuine leak, but the two methods shown in the video above make it simple. Follow the steps below to confirm you have a leak, narrow down the location, and decide whether it's a DIY fix or time to call a specialist.
How Much Water Loss Is Normal?
In a Greek summer a pool can lose up to 5 mm of water per day through evaporation alone—more if there is strong wind or a heating system in use. Anything consistently above that threshold, or visible water around fittings, a wet equipment room, or soggy soil near the shell, is a red flag. The first goal is always to prove you have a leak before spending money on a technician.
Holiday rentals and hotels that run pools continuously are especially exposed: a slow leak in an underground return line can wash away backfill over months before anything looks wrong at the surface. Catching it early with a bucket test takes ten minutes and can save thousands in structural repair.
Where Pool Leaks Most Commonly Hide
The majority of leaks fall into three zones: the pool shell itself (cracks, de-laminated plaster, torn liner), the fittings penetrating the shell (skimmer, lights, return jets, main drain), and the underground or above-ground plumbing between the pump room and the pool. Vinyl-liner pools most often leak around fittings or seams; concrete and fiberglass pools most often leak at the skimmer throat or through surface cracks.
Knowing which zone is likely helps you target your dye testing efficiently rather than squirting dye around the entire pool—which stains grout and gives misleading results.
5 Steps to Find a Pool Leak
- 1
Do the bucket test to confirm evaporation vs. leak
Fill a plastic bucket with pool water to about 3 cm from the top and place it on a pool step so it sits in the water. Mark the water level inside the bucket and the pool water level on the outside with a waterproof marker. Leave the pump running normally for 24 hours, then compare the two drops. If the pool dropped significantly more than the bucket, you have a leak. Matching losses mean the difference is evaporation only.
- 2
Inspect fittings and the skimmer throat first
Turn off the pump and let the water settle. Examine the skimmer basket area closely—the joint between the skimmer throat and the pool shell is the single most common leak point. Also check light niches, return jet faceplates, and the main drain cover for cracks, missing putty, or movement. Press gently on each fitting; any give can indicate a broken seal beneath the surface.
- 3
Use leak-detection dye around suspected spots
With the pump off and water calm, draw a small syringe of dye and release a thin stream directly in front of each suspicious fitting, crack, or seam. Watch the dye; if it drifts toward and is pulled into a spot, water is flowing out there and you have found your leak. Work methodically from one end of the pool to the other so you do not miss secondary leaks.
- 4
Check the plumbing with a pressure test
If no surface leak is found but the bucket test is still positive, the leak is almost certainly underground in the plumbing. Close all valves and pressurize each pipe circuit with air or nitrogen. A circuit that cannot hold pressure has a break somewhere in the run. Note which circuit fails—skimmer line, main drain, or return—so the repair crew knows exactly where to dig.
- 5
Mark findings and decide: DIY repair or call a specialist
Small skimmer-throat gaps and surface cracks under 3 mm can often be sealed with pool-rated hydraulic putty or two-part epoxy while the pool is full—no draining required. Torn liner seams can be patched with underwater adhesive patch kits. Any confirmed underground plumbing leak, a light niche with live wiring nearby, or a structural wall crack needs a licensed pool technician. Document your dye-test findings with photos so the specialist can quote accurately.
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FAQ
- How long should I run the bucket test?
- 24 hours is the standard minimum. For more reliable results, especially in windy conditions, run it for 48 hours and average the two days. Always run the pump at its normal schedule during the test so pipe-line water pressure conditions are realistic.
- Can I dye-test the pool myself without special equipment?
- Yes. A basic dye-test syringe kit costs around €10–15 at pool supply shops and is reusable. The only preparation needed is calm water—turn the pump off for at least 30 minutes before testing so there is no current to scatter the dye before it can show a leak direction.
- What if my pool loses water only when the pump is running?
- That points strongly to the plumbing or fittings on the pressure side—return jets, pump unions, or filter connections—rather than the shell. Check all above-ground pipe joints and valve unions for drips while the pump is on. If nothing is visible above ground, a pressure test of the underground return lines is the next step.