How to Find and Fix a Pool Leak: A DIY Guide

Noticing that your pool's water level is dropping faster than usual can be stressful. While some water loss is normal due to evaporation and splash-out, significant drops could indicate a leak. A pool leak not only wastes water and expensive chemicals but can also damage your pool's structure and equipment. This guide will walk you through the steps to determine if you have a leak and how to systematically search for its source.

Step 1: Evaporation or a Leak? The Bucket Test

Before you start tearing things apart, you need to confirm you actually have a leak. The easiest way to do this is with the "bucket test."

1. Fill a Bucket: Place a 5-gallon bucket on your pool's second step. Fill it with pool water so that the water level inside the bucket is the same as the pool water level outside the bucket.
2. Mark the Levels: Use a waterproof marker or a piece of tape to mark the water level on both the inside and the outside of the bucket.
3. Turn Off the Pump: Turn off the pool pump and any auto-fill devices.
4. Wait 24 Hours: Let the bucket sit undisturbed for 24 hours. This allows both the pool and the bucket to be exposed to the same environmental conditions (sun, wind, rain).
5. Compare the Levels: After 24 hours, check the marks.
   • If the water level in the pool has dropped more than the water level inside the bucket, you have a leak.
   • If both levels have dropped by the same amount, your water loss is due to evaporation.

Step 2: Is the Leak in the Plumbing or the Structure?

If the bucket test confirmed a leak, the next step is to determine if the leak is in the plumbing lines or the pool's structure (shell).

1. Repeat the Bucket Test (Pump On): Perform the bucket test again, but this time, leave the pool pump running for the full 24 hours.
2. Analyze the Results:
   • If the pool loses more water with the pump on than it did with the pump off, the leak is likely in the pressure-side plumbing (the lines that carry water from the filter back to the pool). The pressure is forcing water out of a crack or bad fitting.
   • If the pool loses water at the same rate whether the pump is on or off, the leak is likely in the pool structure itself (a crack in the plaster, a tear in the liner, or around a fitting).
   • If the pool loses more water with the pump off, the leak is likely on the suction side of the plumbing (the lines from the skimmer and main drain to the pump). When the pump is off, water from the pool is leaking out of the pipes. When it's on, it's sucking air in through the leak.

Step 3: Common Leak Locations and How to Find Them

Now that you have an idea of where the leak might be, you can start a more focused search.

The Equipment Pad

This is the easiest place to check. Carefully inspect the pump, filter, heater, and all visible plumbing. Look for drips, wet spots, or mineral deposits on the equipment or the concrete pad underneath. Pay close attention to the pump lid O-ring and all threaded connections.

The Pool Skimmer

The skimmer is the most common source of leaks. The connection between the plastic skimmer and the concrete pool shell can separate over time. To check this, you can use pool leak detection dye.

1. Turn off the pump so the water is still.
2. Carefully release a small amount of dye near the mouth of the skimmer.
3. Watch the dye closely. If it gets sucked into a crack or seam, you've found your leak.

Pool Fittings and Accessories

Use the dye test method around any place where an object passes through the pool shell. This includes:

• Return jets
• Lights
• Steps and ladders
• Main drain cover (use goggles to check this one)

The Pool Liner or Structure

For vinyl liner pools, look for any tears or rips, especially around fittings. For plaster or gunite pools, look for cracks. You can use the dye test on any suspicious-looking crack to see if the dye gets pulled in.

When to Call a Professional

DIY leak detection can be effective for finding obvious leaks. However, if you've gone through these steps and still can't find the source, or if you suspect the leak is in an underground plumbing line, it's time to call a professional. Leak detection companies have sophisticated equipment, like electronic listening devices and pressure testers, that can pinpoint underground leaks with incredible accuracy.

Finding and fixing a leak promptly will save you money on water and chemicals, like the salt you carefully measure with our main calculator, and protect your pool from more serious damage. It's a bit of detective work, but well worth the effort.