Is Your Pool Leaking or Just Evaporating? How to Tell in a Sacramento Summer
Every July we get the same call: “My pool is dropping fast. Is it leaking?” Sometimes the answer is yes. Just as often it’s a normal Sacramento summer doing what it does: hot, dry air and the evening Delta breeze pulling water out of the pool faster than most people expect.
The trick is knowing how to tell if your pool is leaking or just evaporating before you spend money on the wrong fix. Here’s what’s normal, a simple test you can do this weekend, and the signs that mean it’s time to call someone.
How much water does a pool lose to evaporation?
In peak summer, an uncovered pool commonly loses about a quarter inch of water a day. That works out to roughly 1.5 to 2 inches a week. On a typical 15-by-30-foot pool, every inch of water is about 280 gallons.
Three local conditions push that number higher:
- Heat. Warm water evaporates faster, and our pools often run in the high 80s by late July.
- Dry air. Low humidity pulls moisture off the surface much faster than a humid climate would.
- Wind. This is the one people underestimate. In one California water district’s calculation, the same pool lost about three times as much water with a steady 5 mph breeze as it did in still air. The evening Delta breeze that cools Elk Grove and Sacramento off at night is great for us, and hard on your water level.
Waterfalls, spillover spas, fountains and heavy splashing add more on top of that. So does running a heater.
Signs you might have a leak instead
Evaporation is steady and tracks the weather. Leaks don’t care about the weather. Watch for:
- Losing more than about half an inch a day, or more than 2 inches a week during mild weather
- An autofill that seems to run constantly, or a water bill that jumped for no clear reason
- Wet or soggy ground near the pool, the equipment pad, or between the two
- Water dripping or spraying at the pump, filter, valves or heater
- Air bubbles in the pump basket or spurting from the return jets
- New cracks in the plaster or deck, or loose tiles at the waterline
- Chemicals that never stay balanced, because fresh water keeps diluting them
That last one ties into water clarity. Constant top-offs throw off your chlorine and pH, which is a common reason pools turn cloudy in summer.
How to do a pool bucket test
The bucket test is the simplest way to compare evaporation with a leak. The bucket loses water only to evaporation, while the pool loses water to evaporation plus any leak. Put them side by side for a day and the difference tells you a lot.
- Turn off the autofill. If your pool has one, shut it off for the test. Otherwise it quietly refills the pool and hides the loss.
- Set a bucket on the first or second step. Use a 5-gallon bucket. Weigh it down with a brick or rock so it stays put.
- Fill the bucket to match the pool level. The water inside the bucket should line up with the pool water outside it.
- Mark both levels. Put a piece of tape or a marker line at the water level inside the bucket and on the outside of the bucket at the pool level.
- Run the pump on its normal schedule for at least 24 hours, ideally two to three days. Don’t swim, and skip the test if a windstorm or rain is coming.
- Compare the drops. If the pool and bucket fell about the same amount, that’s evaporation. If the pool dropped noticeably more, you likely have a leak.
Narrowing down where the leak is
If the pool lost more, repeat the test with the pump off for 24 hours.
- Pool loses more with the pump running: the leak is likely on the pressure side, in the return plumbing or equipment after the pump.
- Pool loses the same either way: the leak may be in the pool shell, a light niche, or the skimmer.
- Pool loses more with the pump off: look at the suction side, the lines feeding the pump. Running, they pull air in instead of letting water out.
If the water level stops dropping at a certain point, such as the bottom of the skimmer opening or a light, that’s often where the leak is.
Where we find most summer leaks
In our experience, a lot of the “my pool is leaking” calls we get are at the equipment pad, not in the pool itself. Summer heat and long run times are hard on equipment. Common culprits include:
- A cracked pump lid or a worn lid O-ring. These often show up as air in the pump basket before they show up as a puddle. Our pool pump repair page covers what we check.
- Leaking unions, valves or a filter tank O-ring
- A heater with a failing heat exchanger or fitting. We cover heater leaks on our pool heater repair page.
- An autofill valve stuck open, which can overflow the pool or send water down the overflow line
- A hose bib or irrigation line near the pool that’s being mistaken for a pool leak
These are usually quick, affordable repairs once someone finds them. A leak in the pool shell or in plumbing under the deck is different. Those need a leak-detection specialist with pressure-testing equipment, and we’ll point you in the right direction if that’s what it looks like.
Why it's worth fixing quickly
Why it’s worth fixing quickly
A small leak doesn’t stay small. Water escaping under a deck can wash out the soil underneath and lead to cracking. A pump that loses its prime can run dry and burn out its seals or motor. And every gallon you replace costs water, plus the chemicals to rebalance it.
How to cut down on normal evaporation
If the bucket test says it’s just evaporation, you can still slow it down:
- Use a solar cover overnight. Covers block most evaporation when the pool isn’t in use.
- Turn off waterfalls and spillovers when nobody’s enjoying them.
- Lower the heater setting, or turn it off during heat waves.
- Keep the water level in the middle of the skimmer opening, not overfilled.
Frequently asked questions
How long should I run a bucket test?
At least 24 hours, and two to three days gives a clearer answer. Keep the autofill off and skip swimming. Run it again with the pump off if the first test shows a difference.
Can an autofill hide a pool leak?
Yes. An autofill keeps topping off the pool, so you never see the level drop. A higher water bill or constantly fresh-tasting water is often the only clue.
Does a pool lose more water with the pump running?
Not from evaporation alone, except with waterfalls or spillovers running. If the pool loses noticeably more with the pump on, suspect a leak on the pressure side of the plumbing.
Not sure what your water level is telling you?
If your bucket test points to a leak, or you just don’t want to spend another weekend watching the waterline, give us a call. We’ll check your pump, filter, heater, valves and autofill for the leaks we find most often, and tell you plainly what we see.
Our weekly pool service customers get this kind of attention every visit. A technician who sees your pool every week notices a dropping water level or a weeping pump lid long before it becomes a big repair. We serve Sacramento, Elk Grove and the surrounding communities.
Call (916) 892-0684 or request a free quote and we’ll help you figure out where your water is going.
