Why Is My Pool Losing Water? Leak vs. Evaporation in San Antonio

If you've been topping off your pool more than usual lately, you're not imagining it. Right now, in the middle of a San Antonio summer, pool water levels are dropping faster than most homeowners expect. The question is whether what you're seeing is normal or a sign of something that needs to be fixed.

Here's how to tell the difference, and what to do once you know.

How Much Water Loss Is Normal in San Antonio?

In South Texas, pool evaporation is a real and constant thing. During peak summer, most pools lose between 1/4 and 1/2 inch of water every single day just from heat and sun exposure. With temperatures regularly sitting above 100 degrees from June through September, low humidity, and steady afternoon wind, that adds up fast.

Over the course of a week, that's 2 to 3 inches of water gone from evaporation alone. If you're running a spa, water feature, or raised spillover, you can expect even more.

So if you're losing water right now, it doesn't automatically mean something is wrong. But it also doesn't mean you should ignore it.

The Bucket Test: The Easiest Way to Know for Sure If You Have A Pool Leak vs Evaporation

Before you call anyone or start worrying, try this first to know if you have a pool leak vs. evaporation. The bucket test is simple, free, and gives you a real answer.

Here's how it works:

1. Fill a 5-gallon bucket with pool water and set it on the first or second step inside your pool.

2. Mark the water level on both the inside of the bucket and on the pool wall with tape or a grease pencil.

3. Turn off your auto-fill valve if you have one.

4. Run your pool normally for 24 to 48 hours.

5. Check both water levels when time is up.

   
   

If the pool lost significantly more water than the bucket, you likely have a leak. If they dropped about the same amount, what you're seeing is evaporation.

It's low-tech, but it works. Pool professionals use the same basic method as a starting point.

Signs You Might Have an Actual Leak

Evaporation is slow and consistent. A leak usually shows up differently. Here are the things to watch for:

• Losing more than 1 inch of water per day, consistently

• Wet or soggy ground near the equipment pad, pool shell, or return lines

• Visible cracks in the tile, coping, or plaster

• Air bubbles coming out of the return jets

• Your auto-fill running way more than usual

• A spike in your water bill or chemical costs without a clear reason

One of these on its own might not mean much. But if you're checking two or three of these boxes at the same time, it's worth having someone take a look before it gets worse.

Where Pool Leaks Usually Start

Not all leaks are the same, and the fix depends a lot on where the problem is coming from.

• Underground plumbing: Pipes can crack over time, especially in areas with shifting soil. San Antonio and the surrounding Hill Country sit on expansive clay and caliche, which moves with moisture. That movement puts stress on plumbing over time, and leaks underground are easy to miss because you can't see them.

• The pool shell: Cracks in the plaster, gunite, or fiberglass allow water to seep out slowly. Some are visible at the waterline. Others only show up during a pressure test.

• Fittings and returns: The gaskets around skimmers, lights, and return jets wear down. Where water meets the wall is one of the most common places for slow leaks to develop.

• The equipment pad- Pump housings, valves, and filter connections are worth checking too. These are usually visible and often get overlooked until the problem is already significant.

What to Do Once You Know

If the bucket test points to evaporation, the good news is there are some practical ways to slow it down:

• Use a pool cover when the pool is not in use, especially overnight

• Run your pump during cooler hours when possible

• Keep your water chemistry balanced to cut down on splash-out and backwashing

• Check that your water feature or spillover is not creating excessive splash

  
  

If you suspect a leak, the right move is to get a professional leak detection done sooner rather than later. A trained technician can use pressure testing and dye testing to pinpoint exactly where the water is going without guessing and without unnecessary digging.

The reason it matters to act quickly is that small cracks get bigger. A slow leak near the tile line can speed up calcium scaling and surface damage. With San Antonio's hard water, once calcium buildup sets in along a crack or seam, you're looking at more than just a leak repair.

Ready to Find Out What's Going On?

At South Texas Pool Tile Cleaning, we work on pools all over San Antonio, Boerne, New Braunfels, Bulverde, and the surrounding Hill Country. If you've noticed your water level dropping and want a professional set of eyes on it, reach out for a free quote. We'll help you figure out what's happening and what needs to happen next.

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