Is Your Pool Losing Water for No Obvious Reason?

Is your pool water level dropping and you’re not sure why? Don’t panic—there are a few common reasons this might be happening, and not all of them are cause for alarm. Still, it’s important to understand the possibilities so you can take the right action.

Evaporation: A Natural Cause

The most common and harmless reason is evaporation, especially in warm or sunny climates. On average, a pool can lose between 0.1 and 0.25 inches (0.3 to 0.6 cm) of water per day due to evaporation alone. Factors that increase evaporation include:

• High temperatures and direct sun exposure

• Constant wind

• Warm water temperatures

• Frequent use or water movement

If the water loss is minor and consistent, there’s usually no need to worry.

Mechanical Issues: Valves, Pumps and Skimmers

When water loss seems excessive, it’s time to inspect the pool equipment:

• Faulty check valves: A damaged check valve can allow water to flow out when the system turns off.

• Leaky skimmers: Cracks around the skimmer or faulty connections can let water escape.

• Poorly sealed pumps or filters: Loose fittings or lids may lead to ongoing leaks.

Could It Be a Structural Leak?

If evaporation is ruled out and everything seems to be working fine mechanically, it might be a structural leak. These often occur in:

• Cracks in the pool shell

• Poorly sealed joints

• Worn-out seals around lights, return jets or drains

A common sign of a leak is that the water level always stops dropping at the same spot. That’s usually where the leak is located.

Bucket Test: Your Best DIY Ally

Place a bucket of water on the pool’s top step. Mark the water level inside the bucket and in the pool. After 24–48 hours, compare the two. If the pool water dropped more than the water in the bucket, it’s probably not evaporation—it’s a leak.

Don’t Ignore the Signs

If your pool is losing water and there’s no clear reason, don’t brush it off. Figuring out whether it’s due to evaporation, a mechanical issue, or a structural leak can save you serious money and prevent bigger damage in the future. When in doubt, a professional inspection is your best investment.