Losing water — leak or evaporation?
Step 1 of 3
How much water are you losing in 24 hours?
Mark the water line at the same time on two dry days. Rain and heavy swimming both distort the number.
Why the bucket test settles it
Evaporation removes water from every open surface at the same rate, so a bucket sitting in the pool loses water exactly as fast as the pool does. When the pool falls further than the bucket, the difference is going somewhere else — a seam, a fitting, the light niche or the plumbing underground.
Run it with the pump off, on a day without rain, and mark both levels with tape so you are comparing numbers rather than memory. Twenty-four hours is enough; a weekend gives a cleaner signal.
What normal loss looks like
A GTA pool loses about 3–6 mm a day in July, and a windy day at 30°C can double that. If you are topping up weekly and the water is still at mid-skimmer, you are probably watching evaporation. Topping up daily is the pattern that points at a leak.
1/8 in/day
Normal in summer
1/4 in/day
Borderline — test it
1/2 in/day
Leak until proven otherwise
Common questions
Water loss, answered plainly
If the diagnostic points at a leak, the repair page lists what a pressure test, liner repair and fitting replacement cost in your city.
How much water should a pool lose per day in Ontario?
Expect roughly 3–6 mm (1/8 to 1/4 inch) per day in a GTA summer, and more on a hot, windy, low-humidity stretch. A 16 × 32 pool can lose several hundred litres a week to evaporation alone. Sustained loss above a quarter inch a day is worth testing.
How do I run a bucket test?
Fill a bucket with pool water and set it on the top step so it sits in the pool at the same temperature. Mark the level inside the bucket and the pool level on the wall. Turn the pump off and wait 24 hours. If the pool dropped further than the bucket, the pool is leaking.
Can a liner leak fix itself?
No. A pinhole may briefly seal with debris, but water behind the liner keeps washing out the base and the seam keeps opening. Small tears near the waterline can be patched, but a liner that is losing water behind it needs the bead and the shell checked, not another patch.
Should I drain the pool to find the leak?
No. Draining removes the weight holding an inground shell down, and a high water table can float it. If you suspect groundwater pressure, keep the water level up and have the hydrostatic relief valve checked instead.
Leak confirmed? Get it priced.
Tell us the city and what you are seeing. We match the job with local crews who do pressure tests and liner work — no fee, no obligation.