Pool Leak Detection: How to Know If Your Pool Is Leaking

Houston is a pool city. With summer temperatures regularly climbing into the upper 90s and humidity that makes the air feel thick enough to swim through, a backyard pool isn't a luxury — it's a survival tool. But pools require constant maintenance, and one of the most common problems Houston pool owners face is water loss.

Some water loss is normal. Evaporation, splash-out, and backwash all contribute to gradual water level drops. But when your pool is losing more water than it should, you might have a leak — and pool leaks don't fix themselves. They get worse over time, waste water, damage your pool structure, and can even affect your home's foundation.

Here's how to tell if your pool is leaking, what to look for, and when it's time to call in a professional.

How Much Water Loss Is Normal?

Before you start worrying about a leak, it helps to understand what normal water loss looks like in Houston's climate.

In the Greater Houston area, pools typically lose about 1/4 inch of water per day to evaporation during the summer months — roughly 1.5 to 2 inches per week. During cooler months or overcast periods, evaporation slows significantly. Wind, sun exposure, water temperature, and whether you use a pool cover all affect evaporation rates.

If your pool is losing more than 2 inches per week consistently — or if you notice the water level dropping faster than usual — it's worth investigating further. A difference of even 1/4 inch per day between normal evaporation and actual water loss can add up to hundreds or thousands of gallons per month.

The Bucket Test: A Simple DIY Check

The bucket test is the classic way to determine whether your pool is losing water to evaporation or to a leak. Here's how to do it:

1. Fill a 5-gallon bucket with pool water and place it on the first or second step of your pool, so it's partially submerged. Weight it down with a rock or brick if needed to keep it stable.
2. Mark the water level inside the bucket with tape or a marker. Then mark the pool water level on the outside of the bucket.
3. Turn off your pool pump and autofill (if you have one). You want both the bucket and the pool to be affected only by evaporation.
4. Wait 24 hours. Don't use the pool during this time.
5. Compare the marks. If the pool water level has dropped significantly more than the bucket water level, your pool is likely leaking. If both dropped roughly the same amount, you're seeing normal evaporation.

For the most accurate results, run the bucket test on a calm day without rain. Wind can increase evaporation from the pool's larger surface area and skew the results. You can also run the test twice — once with the pump off and once with it running — to help determine whether the leak is in the pool shell or the plumbing.

5 Signs Your Pool Has a Leak

1. Consistent Water Level Drops

The most obvious sign is a water level that keeps dropping despite regular filling. If you're adding water to your pool more than once a week during the summer — or at all during the winter — something is wrong. Track your water level daily for a week by marking the tile line or skimmer level with tape. If it drops more than 1/4 inch per day consistently, a leak is likely.

2. Chemical Imbalance and Increased Chemical Use

When a pool leaks, it's not just losing water — it's losing the chemicals dissolved in that water. If you're constantly fighting to maintain proper chlorine levels, pH balance, or alkalinity despite regular treatment, a leak may be diluting your pool with fresh groundwater or causing you to lose treated water faster than expected.

A pool that was easy to maintain for years and suddenly becomes hard to balance chemically is a red flag worth investigating.

3. Wet Spots, Soggy Areas, or Erosion in Your Yard

If you notice areas of your yard that are consistently wet, soggy, or muddy — especially near the pool, pool equipment, or along the plumbing runs — a leak may be saturating the soil from below. Look for:

• Unusually green or lush patches of grass near the pool
• Soft or spongy spots in the lawn
• Erosion or sunken areas near the pool deck
• Standing water that doesn't dry up between rainstorms
• Shifting or cracking pool deck sections

In Houston, this is particularly concerning because of our clay soil. When clay soil absorbs excess water from a pool leak, it expands. When it dries, it contracts. This expansion-contraction cycle can cause your pool deck to shift, crack, or separate — and if the pool is near your house, it can even contribute to foundation movement.

4. Cracks in the Pool Shell or Tile

Visible cracks in your pool's plaster, gunite, or tile don't always mean you have an active leak — but they're a common entry point for one. Even hairline cracks can allow water to seep through, especially under the hydrostatic pressure of a full pool.

If you notice new cracks forming, existing cracks getting larger, or tiles popping off the pool wall, the underlying structure may be shifting due to soil movement. Houston's expansive clay soil puts constant pressure on pool shells, and a small crack can quickly become a significant leak path.

Inspect your pool shell regularly — especially at the tile line, around fittings (skimmers, returns, lights), and at the joint between the pool wall and floor. These are the most common failure points.

5. Air Bubbles in the Return Lines or Pump Issues

If you see air bubbles coming from your pool's return jets when the pump is running, air is being drawn into the plumbing system somewhere. This usually means there's a crack or break in a suction-side pipe (between the skimmer and the pump) that's allowing air in.

A pipe that lets air in can also let water out, especially when the pump shuts off and pressure equalizes. Other equipment-related signs include:

• The pump strainer basket losing its prime frequently
• Visible water around pool equipment pads
• Cracked or damaged fittings at the equipment pad
• The pump running dry or making unusual noises

The Houston Factor: Clay Soil and Pool Leaks

Houston's soil plays a major role in pool leak issues. The expansive clay that makes up much of the Houston metro area's subsoil behaves differently than the stable, sandy soils found in other parts of Texas. Here's why that matters for pool owners:

• Soil movement stresses pool shells. As clay expands and contracts with moisture changes, it puts uneven pressure on pool structures. This can crack plaster, pop tiles, and separate joints — all of which create leak paths.
• Leaking water makes soil movement worse. A pool leak saturates the soil on one side, creating differential moisture conditions. One side of the pool sits in wet, expanded soil while the other sits in drier, contracted soil. This uneven support accelerates structural damage.
• Underground plumbing is vulnerable. Pool plumbing runs through this active soil zone. As the ground shifts, rigid PVC pipes can crack at joints or separate from fittings. Flexible plumbing connections help, but older pools often have rigid runs that are susceptible to movement.

This is why early detection matters so much for Houston pools. A small leak that might be a minor issue in stable soil becomes a compound problem in our clay — the leak causes soil movement, which causes more structural damage, which causes more leaking.

Professional Pool Leak Detection Methods

When the bucket test confirms you're losing water beyond normal evaporation, or when you see the signs listed above, it's time to call a professional. Here's what a professional pool leak detection inspection typically involves:

• Pressure testing: Each plumbing line (skimmer, main drain, return lines, spa jets) is individually pressure tested to determine if the leak is in the plumbing or the shell. Lines that don't hold pressure have a breach somewhere along their run.
• Dye testing: A non-toxic dye is introduced near suspected leak points — cracks, fittings, lights, and joints. If water is escaping at that point, the dye will be visibly drawn into the crack, confirming the leak location.
• Hydrophone testing: An underwater listening device (hydrophone) amplifies the sound of water escaping through cracks or pipe breaches. The technician submerges the hydrophone and moves it along suspected areas, listening for the distinctive sound of a leak.
• Electronic detection: For plumbing leaks, electronic leak detection equipment can locate breaches in buried pipes without excavation.
• Thermal imaging: FLIR thermal cameras can sometimes detect temperature differences in the pool deck or surrounding soil caused by leaking water, helping pinpoint underground plumbing leaks.

What to Do If You Suspect a Pool Leak

Here's our recommended approach for Houston pool owners who suspect a leak:

1. Run the bucket test to confirm the water loss exceeds normal evaporation.
2. Check the obvious. Inspect around your pool equipment for visible drips. Check the backwash line. Look for wet spots in the yard.
3. Document the water loss. Mark your water level daily and track how much you're losing. This information helps the leak detection technician.
4. Don't drain the pool. A full pool is easier to test, and draining a pool on Houston clay soil can cause the shell to pop or shift if the water table is high.
5. Call a professional leak detection company. A specialist with the right equipment can find the leak quickly and give you a detailed report so your pool contractor can make a targeted repair.

At Exact Leak Detection HTX, we provide comprehensive pool leak detection services for Houston pool owners. Our inspections include pressure testing, dye testing, and a detailed report with findings and recommendations. We find the leak — your pool service company or contractor handles the repair.