Pools · Service

Pool leak detection, after you have proved there is a leak

Most suspected leaks are evaporation. The test that tells you costs nothing and takes a day. Do it before you call anyone — then treat detection and repair as two separate purchases.

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In short

What is pool leak detection & repair?

Pool leak detection is the process of confirming that a pool is losing water beyond normal evaporation, then locating where — the shell, a fitting, the plumbing, or somewhere in the equipment pad. Repair is a separate job that depends entirely on what is found, from a fitting reseal costing very little to excavating a buried line. The first step costs nothing: a bucket test run over a day or two will tell you whether you have a leak at all, and a large share of suspected pool leaks turn out to be evaporation, splash-out or backwash water.

Triggers

Signs you need pool leak detection & repair

You are topping up more often than you used to, and the change is not explained by hotter weather or heavier use
The water settles at a consistent level and stops — which often points at a fitting or a skimmer at that height
There is a persistently wet or unusually green patch in the yard, or near the equipment pad
Air keeps appearing in the pump basket or the returns, which can mean a suction-side leak drawing air in
Your chemical consumption has climbed because you are constantly diluting the pool with fresh water
Cracks, gaps or movement have appeared at the tile line, around fittings, or in the deck near the pool
The autofill is running far more than it should, or your water bill has stepped up

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The job

How pool leak detection & repair actually works

Prove it first — the bucket test

Stand a bucket of pool water on a step so the levels inside and outside match, mark both, and compare after a day or two with the pump running normally. Both dropping equally means evaporation; the pool dropping faster means a leak.

Watch for: Paying for detection before doing this. It is free, it is definitive, and a company that discourages it before quoting is telling you what kind of company it is.
Narrow it down — plumbing or structure?

Comparing loss with the pump running against loss with it off is the classic split: faster loss with the pump on points at pressure-side plumbing, faster with it off points elsewhere. Where the level stabilises is another strong clue.

Watch for: A quote to excavate before this narrowing has been done. Digging is the expensive answer and it should be the last one, not the first.
Detection — pressure testing and listening

Lines are isolated and pressure-tested individually to find which one is failing. Acoustic listening equipment, dye testing at fittings and cracks, and sometimes cameras are used to pinpoint the location.

Watch for: A vague result. You are paying for a location, not for an opinion. Ask what the deliverable is: which line, or which fitting, and where.
Get the finding in writing before agreeing any repair

Detection and repair are genuinely different services with different skills, and some companies do only one. A written finding lets you get the repair priced by more than one party.

Watch for: A single price covering "find and fix". It removes your ability to compare the repair, and the repair is usually the larger number by a wide margin.
Repair, scoped to what was actually found

Fitting and skimmer leaks are resealed. Liner punctures are patched. Shell cracks are addressed structurally. Failed lines are either repaired at the point of failure or bypassed with a new run, which is often cheaper than chasing an old line under a deck.

Watch for: Cosmetic repair of a structural crack. If the shell is moving, sealing the crack is a delay rather than a fix, and the underlying cause needs a proper opinion.
Verify the fix

The pool is refilled and monitored, ideally with a repeat bucket test, to confirm the loss has actually stopped rather than reduced.

Watch for: Pools with more than one leak. It is common enough that "it is better but not fixed" should be treated as a second leak rather than as a failed repair.

Money

What does pool leak detection & repair cost?

Detection is usually a fixed call-out and investigation fee. Repair is separate and spans from a very small fitting reseal to excavating and replacing a buried line under a deck. Insist on the two being quoted separately — the gap between them can be a hundredfold.

See the full pool leak detection & repair cost guide — by material, size and region →

Volume calculators → Working out how much water you are losing.

Straight answer

When pool leak detection & repair is the wrong call

Everyone else ranking for this is paid when you say yes. Here's when you shouldn't.

You have not run a bucket test. Evaporation in hot, dry, windy weather on an uncovered pool is far larger than most owners believe. Spend two days and nothing before you spend anything.
You are about to resurface or remodel anyway. If the pool is coming down soon, some leak repairs are much cheaper as part of that work. Coordinate rather than paying for access twice.
The loss is small and the pool is old with a failing finish. Chasing a minor leak on a pool that needs resurfacing within a year or two can be money spent on a surface that is about to be removed. Get both assessed together.
Nobody has ruled out backwash, splash-out and a stuck autofill. A valve passing water, an autofill that never shuts off, or heavy use with children can all look exactly like a leak on the water bill.
The detection company will only quote find-and-fix as one number. You lose all leverage on the expensive half of the job. Insist on separation, or find someone who will.

Before you sign

What to check when hiring for pool leak detection & repair

Do you charge separately for detection and for repair?

The most valuable question in this category. Bundled pricing hides the expensive half and removes your ability to compare it.
What is the deliverable from the detection visit?

You are buying a location — a named line or a specific fitting. "We think it is somewhere in the plumbing" is not a result you should pay for.
Will you pressure-test the lines individually?

It is how plumbing leaks are actually isolated. A visit without it is largely guesswork with equipment.
If it is a buried line, is bypassing cheaper than chasing it?

Running a new line is frequently cheaper than excavating a deck to find an old one. A good technician raises this unprompted.
How do you verify the repair worked?

Multiple leaks are common. You want an agreed verification step rather than a bill and a hopeful goodbye.
If the finding is a structural crack, who assesses why the shell is moving?

Sealing a moving crack is a delay. The cause is a different question and may need someone else entirely.

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Local pros

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Related work

Often done at the same time

Pool Resurfacing

Never resurface over an undiagnosed leak

Pool Remodeling

When to bundle the repair into bigger work

Pool Equipment Installation

Pad leaks and plumbing that keeps failing

Pool Maintenance Service

Who usually spots the loss first

All pools services →

FAQ

Pool Leak Detection & Repair — questions people ask

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How much water loss is normal for a pool?

Enough to surprise people. Evaporation depends on temperature, humidity, wind and surface area, and on a hot dry breezy day an uncovered pool loses a genuinely noticeable amount without anything being wrong. That is exactly why the bucket test exists — it compares your pool against a control sitting in the same conditions, which cancels out the weather. Run it before drawing any conclusions, and run it again after any repair.

How do I do a bucket test?

Put a bucket on a pool step so it is stable, fill it with pool water until the level inside matches the pool level outside, and mark both levels — inside the bucket and on the pool wall or skimmer. Leave everything running as normal and do not let anyone swim. After twenty-four to forty-eight hours, compare. If both dropped by the same amount, it is evaporation. If the pool dropped more than the bucket, you have a leak worth investigating.

Where do pool leaks usually happen?

The common places are the fittings — skimmer throats, return eyeballs, light niches and main drains — where a seal has failed; the plumbing lines, especially at joints; the equipment pad, where a small drip can add up; and the shell itself, through a crack or a liner puncture. Where the water stops falling is a strong clue, because a pool typically drains to the level of the leak and then holds there.

Can I find a pool leak myself?

You can do the useful first steps: the bucket test to confirm there is a leak, noting the level where it stabilises, comparing loss with the pump on versus off, and looking for wet ground or a suspiciously green patch in the yard. Dye testing visible fittings and cracks is also within reach. What is not is isolating and pressure-testing buried lines, which needs equipment and access to the plumbing. Do the free part, then hand over a well-observed problem.

Is it worth fixing a small pool leak?

Usually yes, and for reasons beyond the water bill. A constant trickle of make-up water means constantly rebalancing chemistry and constantly diluting your stabiliser, which makes the pool harder to keep. Water escaping around a fitting or through the shell also erodes and saturates the ground the pool sits in, which is a much more expensive problem than the leak. The exception is a small leak on a pool that is due for resurfacing shortly — coordinate the two.