Diagnostics
Pool Leak Detection in Los Angeles
A pool that drops more than about a quarter of an inch a day is usually losing it somewhere other than the sky. Finding out where comes before deciding what it costs to fix.
The short answer. A Los Angeles pool loses water every day with nothing wrong with it. About a quarter of an inch a day is ordinary evaporation, and a hot, dry, windy summer stretch pushes that towards half an inch. At an inch a day you are watching a leak, not the weather — on a 16×32 ft pool, roughly 320 gallons a day.
The bucket test below settles which one you have in twenty-four hours. Diagnosis at the equipment pad is free in our service area; underground leak location, pressure testing and excavation are not, and are quoted before work starts. What that means for the bill.
The bucket test: leak or evaporation, in 24 hours
Evaporation empties the bucket and the pool at the same rate. A leak empties only the pool.
Top the pool up
To its normal level — usually halfway up the skimmer mouth.
Stand a 5-gallon bucket on the second step
Weighted so it cannot float, filled with pool water to the level outside.
Mark both levels
Tape inside the bucket, tape outside it, a dated pencil line on the tile.
Switch the autofill off
A pool that tops itself up cannot show a drop. Leave the pump on its normal schedule.
Wait 24 hours, then compare
No swimming, no backwashing. Equal drops mean evaporation; if the pool fell further, that difference is the leak.
Run it again with the pump off
Pump off at the breaker. What changes between the two runs is the diagnosis.
| What the two runs show | What it points at |
|---|---|
| Bucket and pool drop together | Evaporation. Check splash-out and the waste line |
| Faster with the pump running | Pressure side: return lines and their fittings |
| Faster with the pump off | Suction side — skimmer or main drain line — or the shell |
| The same either way | Structural: shell, plaster, tile line, skimmer throat, light niche |
| Falls, then stops dead and holds | The leak is at that depth. Just below the light: the niche. At the skimmer mouth: the throat |
Where pools actually leak
| Where | What gives it away |
|---|---|
| Equipment pad | Wet concrete, mineral crust, an audible drip. Dry with the pump off, wet minutes after it starts |
| Skimmer and its throat | The level falls to the bottom of the skimmer mouth and stops there |
| Light and its niche | The level settles just below the light and holds; dye at the ring is drawn in |
| Returns and jets | Clearly worse with the pump running. Sometimes a softer, greener patch of lawn |
| Shell, plaster, tile line | Identical loss with everything off. A crack with a stain trailing from it |
| Underground plumbing | Nothing visible. Level falling below the tile line, soggy or sunken ground, air in the pump basket, prime lost overnight with a dry pad |
Until the pad is ruled out, nothing underground is worth testing — a leak found there is an ordinary equipment repair. At the far end, one crack in sound plaster is a patch, but a crazed, hollow shell is a case for resurfacing: patching it buys a season.
Why leaks get found in October
It is not that pools start leaking in autumn. Autumn stops hiding it.
The camouflage comes off
A Los Angeles summer pulls water out fast. A pool losing half an inch a day to the weather can be losing another quarter through a crack and still look normal for July. Then the nights cool, evaporation falls to a fraction of the summer figure, and the leak has not changed — the camouflage has.
And the bill arrives
Autumn also brings the summer water bill: months of quiet topping up show on paper long after they stopped showing in the water. If usage stepped up in June and never came down, run the bucket test.
Autofill valves are why this survives a whole summer. A pool with one never shows a low level — it just pays the difference daily. Never switched yours off? You have no evidence either way.
How a leak is actually found
In the order things are cheapest to be wrong, not the order easiest to bill.
The equipment pad
Seal, filter, heater, valves, unions, waste line and the ground around them — running, then off. This part is the free diagnosis.
Dye testing the suspects
Water dead still, a little dye beside a crack, a throat, a niche or a return. A hole draws it in. It confirms a location rather than finding one.
Pressure testing, line by line
Each line isolated at the pad, plugged, put under pressure and watched. One that will not hold is the leaking line — the specialist work priced outside a free diagnosis.
Electronic and acoustic location
Listening equipment follows the sound of water escaping through soil and concrete to a point, so what gets opened is a patch, not a trench.
Underwater inspection
Shell, tile line, throat, niche, main drain and fittings examined in the water, not from the deck.
Why topping it up is the expensive option
The water
An inch a day on a 16×32 ft pool is about 2,200 gallons a week, on a water bill every month until it stops.
The chemistry goes with it
Every leaked gallon takes chlorine, acid, stabiliser and calcium with it; every replacement gallon arrives with none, so the pool chases balance permanently. How weekly service reads that.
So does the heat
On a heated pool you pay to warm water that is leaving. A heater running longer for the same temperature is a quiet, expensive symptom.
The ground under the shell
Water leaving below the waterline goes into soil, not a drain, and over months can wash out what supports the shell or the deck. On hillside lots, into a gradient. All 35 areas.
Before anyone comes out
- Run the bucket test twice
Pump on one day, off the next.
- Switch the autofill off
Nothing measured with it running means anything.
- Mark the level, note where it stops
A dated pencil line on the tile beats any description over the phone.
- Photograph the pad wet and dry
Under the motor, at the clamp band, unions, heater and waste line.
- Find the water bill
The month usage climbed is a date, and a date narrows the search.
And what not to do
- Do not drain the pool
An empty shell in saturated ground can lift, and plaster that dries out gets damaged. Never a diagnostic step.
- Do not pour sealant in first
It can close a pinhole. It can also settle in sound lines, and it destroys the evidence the tests above depend on.
- Do not keep restarting a pump that will not prime
Running dry melts its own wet end in under an hour. What that costs.
- Do not dig at the wet patch
Where water surfaces is not where it left the pipe.
What it costs, said plainly
Leak work is the one part of pool repair where a published number would be dishonest.
- Standard equipment diagnosis is free
In our service area, and it stays free if you decide not to go ahead.
- Underground work is quoted separately
Leak location in buried plumbing, pressure testing and excavation are not part of it; the price is agreed before anything begins.
- Repair labour starts at $175 an hour
One hour minimum, typical repairs quoted as a fixed price in writing. All our prices.
- Members take 20% off
On one-time services, plus priority on the schedule.
Why no figure for finding a leak. An honest one depends on how many lines have to be isolated and tested, and what has to be opened at the end. So we look at the pad for nothing, and you decide with the number in front of you.
Pool Care LA is a trade name of Luxury Estates Builders, Inc., California contractor licence #1117110, classifications B (General Building) and C-53 (Swimming Pool), active through 29 February 2028 and bonded for $25,000 with Jet Insurance. Verify it at cslb.ca.gov.
Questions people ask before they call
How much does it cost to have a pool leak detected?
Checking the pad costs nothing in our service area, and stays free if you do not go ahead. Underground work — pressure testing, electronic location, excavation — is quoted separately, because the honest figure depends on how many lines must be tested. Our prices.
How can I find out where my pool is leaking from?
Two bucket tests and a mark on the tile get you most of the way. Faster loss with the pump running points at the returns; faster with it off, at the suction lines or the shell; the same either way is structural. The procedure is above.
Why is my pool losing 1 inch of water a day?
Because it is leaking. An inch a day is roughly four times normal Los Angeles evaporation — about 320 gallons a day on a 16×32 ft pool. Check the pad, pump running and then off, before assuming it is underground.
Is it normal to lose 2 inches of water out of a pool?
It depends how long it took. At the quarter-inch-a-day rate ordinary here, evaporation alone accounts for nearly two inches a week, so two inches across a week is unremarkable. Two inches in a day is not.
Why is my pool losing water but no leak can be found?
Usually evaporation underestimated on a windy, unshaded pool; splash-out; a backwash valve weeping to waste; an autofill left running during the test; or a pressure-side leak, which a pump-off test cannot show because it only leaks while the pump pushes.
Can you fix a pool pipe leak under concrete?
Yes, and there is usually a choice. Once pressure testing identifies the failing line and acoustic location narrows it to a point, the deck is opened as a small patch and that section repaired — or the run is abandoned and rerouted. We agree the approach and price first.
Tell us what the bucket said
The drop with the pump on, the drop with it off, and the depth the level stops at.
Request a free quote Call (818) 740-6099
Mon–Fri 6am–9pm, Sat–Sun 8am–6pm. Working on Los Angeles pools since 2023. Equipment repair · Weekly maintenance · Service areas