Pool Leak Detection in McLean, VA

Pools lose some water to evaporation, splashing and backwashing. A leak is different: the level keeps dropping, the auto-fill keeps running or wet spots appear around the deck. Finding it early saves water, chemicals and the soil around the pool. Many larger lots around McLean have in-ground pools, so this is a regular part of our leak detection work. Before you call, try the steps in our guide on how to find a leak in a pool.

What our pool leak service includes

• Review of your bucket test or water loss records.
• Equipment pad check: pump, filter, heater and valves.
• Pressure testing of suction and return lines.
• Skimmer, return fitting, main drain and light niche checks.
• Auto-fill valve and supply line testing.
• Spa and spillover plumbing checks.
• Repair of plumbing leaks we find, or a clear report for your pool contractor.

Signs and causes

How we find a pool leak

1. Confirm the loss. We review your bucket test or set one up to confirm the pool is leaking.
2. Pump on vs pump off. Comparing loss with the system running and stopped points to the plumbing or the shell.
3. Check the pad. We look for leaks at the pump, filter, heater and valves.
4. Pressure test the lines. Each suction and return line is isolated and pressurized. A line that loses pressure is leaking.
5. Pinpoint. Acoustic listening helps locate the leak along a buried line.
6. Repair or report. We repair plumbing leaks and give you written findings for any shell or liner work.

Pool leak locations compared

What affects the cost

• Number of lines to pressure test.
• Spa, water features and auto-fill.
• Depth and access of the buried lines.
• Decking or landscaping over the leak.
• Whether the repair is plumbing or structural.

DIY vs calling a pro

The bucket test is the best first step and costs nothing. You can also check the equipment pad for drips and watch whether the level stops dropping at a skimmer or light. Pressure testing and locating buried leaks need special equipment.

Water use and seasonal notes

The EPA's WaterSense program estimates that household leaks waste nearly 1 trillion gallons of water nationwide each year, and an auto-fill on a leaking pool adds to that quietly. In Northern Virginia, check for leaks before closing a pool in fall, since a leak in a line that is not winterized correctly can freeze and split.

Before you call: information that speeds things up

Pool leak detection goes faster when we know a few things before we arrive:

1. Your bucket test results, with the pump running and with it off.
2. How fast the level drops, in inches per day.
3. Whether the level stops dropping at a certain point, such as the bottom of the skimmer or a light.
4. When the problem started, and any recent work on the pool or equipment.
5. Whether you have an auto-fill, a spa, a heater or water features.
6. Where the equipment pad is and how the lines run to it, if you know.

Write these down and share them when you call. They often point straight to the leaking system.

If the pool is losing water fast, more than an inch or two a day, turn off the auto-fill and call. A fast leak can wash out soil under the deck or equipment pad, and the sooner it is found, the smaller the repair.

Local note

In-ground pools are common on larger lots in Great Falls, Vienna and Oakton. Long runs from the pool to a distant equipment pad give leaks more places to hide.

Pool leak detection questions

How do I know if my pool is leaking or just evaporating?

Do a bucket test. Set a bucket of pool water on a step, mark the water level inside the bucket and on the pool wall, and compare after 24 hours. If the pool drops more than the bucket, it likely has a leak.

Where do pools usually leak?

Common spots are skimmer seams, return fittings, main drains, light niches, tile lines, liner tears and the underground plumbing between the pool and the equipment pad.

Can you find leaks in the underground pool plumbing?

Yes. We pressure test each line between the pool and the equipment. A line that loses pressure is leaking, and acoustic listening helps pinpoint where along the run.

Can a pool leak raise my water bill?

Yes, especially with an auto-fill valve that quietly tops the pool up. If your water bill rises in summer, check whether the auto-fill is running more than it should.

Do you repair the leak too?

We repair the plumbing side: underground lines, fittings, equipment pad leaks and the auto-fill supply. Structural repairs to the pool shell, tile or liner may need a pool contractor, and we will tell you if so.

Sources

• U.S. EPA WaterSense — Fix a Leak Week

Last reviewed 2026-11-07. This page is general information, not legal or insurance advice. Read how we research and check pages in our editorial policy.

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Pool leak detection near you

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Helpful guides

• Leaks & Detection

  Find a Pool Leak

  Run the bucket test, narrow down the leak with the pump on and off, and know when to call a pro.

• Costs & Insurance

  Leak Detection Cost

  The factors that raise or lower the price of finding a hidden leak, and how to compare quotes.

• Water & Sewer Lines

  Water Meter Leak Test

  Use your meter's leak indicator to confirm a leak and narrow down where it is.