Is the pool leaking, or is it just Yuma?

Desert evaporation is not a small number

Arizona pool industry data puts typical uncovered-pool evaporation around a quarter inch per day, rising to half an inch daily in June–August conditions -- roughly 4 to 6 vertical feet of water per year. National pool advice frames "normal" as an inch or less per week, which is why articles written for milder climates will tell a Yuma pool owner their completely normal summer loss is an emergency. Run the desert numbers first. (The evaporation deep-dive covers the full seasonal rates and what actually reduces them.)

For scale: on a 400-square-foot pool, half an inch of depth is roughly 400 × 0.5 ÷ 12 × 7.48 ≈ 125 gallons -- per day, purely to the sky (illustrative arithmetic, not a bill). An autofill valve will replace that silently, which cuts both ways: it hides normal evaporation and it can mask a genuine leak for months while the water bill quietly climbs.

The bucket test: 24 hours, settles most cases

1. Turn off the autofill. Fill a bucket with pool water and set it on a pool step so the bucket's rim sits above water, its water surface exposed to the same sun and air.
2. Mark both levels -- inside the bucket, and the pool itself -- with tape.
3. Wait 24 hours (pump running as normal), then compare drops. Equal drops = evaporation. Pool dropped meaningfully more than the bucket = a real loss -- the bucket experienced identical evaporation, so the difference is going somewhere else.
4. Optionally repeat with the pump OFF: loss that's much worse with the pump running points at the plumbing/pressure side; loss that continues pump-off points at the shell, fittings, or suction side.

What professional detection actually includes

A real detection visit is diagnosis, not repair: pressure testing of the plumbing runs, dye testing at suspect points in the shell, skimmers, fittings and returns, listening equipment or isolation testing at the pad, and underground line testing where the evidence points there -- ending in a written diagnosis and a separate repair quote. The $250–$450 published Yuma rate above is for that diagnostic scope; simple dye-test confirmations sit at the bottom of the national $100–$500 band, full underground work at the top.

Licensing note: the moment diagnosis turns into repair -- cutting into plumbing, patching the shell, replacing underground line -- Arizona requires an active ROC pool-classification license. The licensing explainer shows how to verify one before approving repair work.

Signs that skip the bucket test

• Soggy or shifting soil, or unusually green patches, along one side of the pool or above a plumbing run.
• Air bubbles from the returns or air in the pump basket -- suction-side trouble.
• Cracks in the shell or deck that line up with where the water stabilizes when you let the level fall.
• Losing more than an inch a day, any season -- beyond even Yuma's evaporation ceiling.

Any of those justifies going straight to professional detection -- water loss at that rate undermines decks and erodes fill dirt, and the repair grows with the wait.