Every backyard pool loses water constantly, mostly to evaporation, and figuring out whether your pool's water loss is normal or a sign of an actual leak is the first real question worth answering before assuming the worst, or, just as importantly, before ignoring a real problem for months.
What counts as normal evaporation
In Torrance's climate, a reasonable rule of thumb is that a pool loses roughly a quarter-inch of water per day to evaporation under typical conditions, more on hot, dry, or windy days, less on cool, humid, or still ones. That's a rough guideline, not an exact figure, since evaporation rate genuinely varies with weather, pool surface area, and whether a pool cover is used, but it gives you a real baseline to compare against.
The bucket test: how to actually check
This is the standard, reliable way to separate evaporation from a real leak, and it costs nothing but a bucket and a day or two of patience.
- Fill a bucket with pool water and place it on a pool step, so it's partially submerged and experiencing the same temperature as the pool itself.
- Mark the water level inside the bucket and the water level of the pool itself, using tape or a marker, at the same time.
- Turn off the pool's pump and filtration system, since a running pump can mask or mimic a leak through normal splash-out or evaporation from moving water.
- Wait 24 hours, then compare how much the water level dropped in the bucket versus in the pool.
If both levels dropped by roughly the same amount, that's evaporation, since the bucket experienced the same environmental conditions as the pool but has no possible leak of its own. If the pool's level dropped noticeably more than the bucket's, that's a real signal you're dealing with an actual leak, not just weather.
Signs that point toward a leak beyond the bucket test
- Wet or unusually soft ground near the pool equipment pad, pump, or filter, especially without an obvious splash-out source
- Air bubbles coming from the return jets even when the system has been running steadily, rather than just at startup
- Cracks in the pool deck or shell, or new staining that doesn't match a chemical or algae issue
- A consistent, ongoing need to add water more often than the bucket test's normal-evaporation result would suggest
Where pool leaks actually happen
A leak can be in the plumbing lines running between the pool and the equipment pad, buried underground and not visible without testing. It can be at a fitting, a light niche, or a skimmer connection, a more contained, often easier repair. Or, less commonly but more seriously, it can be in the pool shell itself, a structural issue rather than a plumbing one. Figuring out which category applies is exactly what professional leak detection for pools is built to determine, since the diagnostic approach differs meaningfully from household plumbing leak detection given how a pool's system is laid out.
How a professional narrows down a pool leak
Beyond the homeowner-level bucket test, a professional inspection typically includes pressure testing each plumbing line individually, which isolates whether the leak is in the pipes at all versus pointing toward the shell or a fitting instead, along with electronic and dye testing to pinpoint a specific location once pressure testing has narrowed the search. This staged approach avoids unnecessary excavation or repair work based on a guess.
Why waiting on a confirmed leak costs more over time
A pool leak, especially in the plumbing lines, generally doesn't get better on its own, and continuing to simply top off the water level treats the symptom while the underlying issue keeps running up your water bill and potentially causing erosion or damage around the equipment pad or shell. Confirming and addressing a real leak once it's identified is almost always less costly over time than an indefinite pattern of topping off and hoping it resolves itself.
A note on chemical balance and a leaking pool
An ongoing, unaddressed leak doesn't just cost water, it costs you on chemicals too. Every time you top off a pool with fresh water, you're diluting the carefully balanced chemistry you've built up, which means more frequent testing and rebalancing than a pool that's holding its water level normally. Homeowners dealing with an unconfirmed leak sometimes notice the chemical-balance frustration before they connect it to water loss at all, which is worth keeping in mind if your pool maintenance routine has started feeling like more of a moving target than it used to.
What repair actually looks like once a leak is confirmed
The specific fix depends entirely on where the leak turned out to be. A fitting or light-niche leak is often a relatively contained repair, accessible without extensive excavation. A plumbing-line leak further from the equipment pad may require a small, targeted excavation to access and repair the specific section of pipe. A structural shell leak is a different category of repair entirely, and if testing points that direction, we'll say so clearly rather than attempting a fix outside what plumbing repair actually addresses.
Seasonal timing worth keeping in mind
Pool leaks don't announce themselves on a schedule, but a few seasonal patterns are worth knowing. Winter's cooler temperatures and lower evaporation rates mean a bucket test result during that season sets a lower normal baseline than the same test would show in peak summer heat, so comparing a winter reading against a summer expectation can make a perfectly normal pool look falsely alarming. Running the bucket test during roughly the same season and weather conditions you're comparing against gives a more accurate read, and if you're ever unsure whether a given result is normal for the current conditions, that's a reasonable moment to bring in a professional check rather than second-guessing your own test.
Topping off your pool more than it feels like you should?
A bucket test and, if needed, a professional leak check can settle it.