Pool losing water: evaporation or a leak?

Why Kingman pools lose so much water honestly

Evaporation scales with heat, dryness, and wind, and Kingman has all three. Summer afternoons run hot, the high-desert air at 3,300 feet is bone dry, and the wind that works this corridor strips the humid boundary layer off the water surface faster than still air ever would -- the same reason laundry dries in an hour here. Arizona-wide, leak-detection firms measure roughly a quarter inch of evaporation per day under normal conditions and up to half an inch per day in the June–August peak; over a year, an average uncovered Arizona pool can lose four to six vertical feet of water to the air. National sources put "normal" at an inch or less per week outside the desert -- worth knowing, because advice written for milder climates will tell you a rate that is routine here is an emergency.

Kingman's one real difference from Phoenix advice: winter. Cool, shorter days cut evaporation to a small fraction of summer's, so the same half-inch daily drop that is plausible in July is a red flag in December. If your level falls fast in the cool season, skip ahead to the bucket test.

Rough expectations by season

Compiled Aug. 2026 from Arizona leak-detection and national pool-maintenance sources; wind, cover use, and water temperature move these numbers a lot. Research, not a measurement of your pool.

What that is in actual gallons

Inches on a waterline are abstract; gallons on a water bill are not. The conversion is simple arithmetic: gallons lost = pool surface area (sq ft) × inches lost ÷ 12 × 7.48. Applied to common pool sizes:

Straight arithmetic from the evaporation rates above -- illustrative, not a measurement of your pool.

Two things follow from those numbers. First, an autofill valve can be quietly replacing a thousand-plus gallons in a peak-summer week with nothing wrong at all -- so a rising water bill alone doesn't prove a leak. Second, a genuine leak stacks on top of that baseline: a pool losing an inch a day is losing roughly two to four times what the desert can plausibly take, and that gap is exactly what the bucket test measures.

The 24-hour bucket test

The bucket test works because it gives you a control: a bucket of pool water sitting in the pool loses water to evaporation at the same rate as the pool itself, but it cannot leak. Any extra drop on the pool side has to be a leak.

1. Top the pool up to its normal level. Fill the pool to its usual operating level -- mid-skimmer is typical -- so you are measuring from a known starting point.
2. Set a bucket of pool water on a step. Fill a 5-gallon bucket with pool water to about an inch from the top and set it on the first or second pool step, so it sits partly submerged with several inches of bucket above the waterline. The water inside the bucket and the pool around it now share the same sun, air, and temperature.
3. Mark both water levels. With tape or a marker, mark the water level inside the bucket and the pool level outside it. Turn the pump on and run your normal schedule.
4. Wait 24 hours and compare. Read both marks. Both levels drop from evaporation; only the pool drops from a leak. If the pool fell noticeably more than the bucket, water is leaving some way other than the air.
5. Repeat with the pump OFF. Refill, re-mark, and run the same 24 hours with the pump off. Comparing the pump-on and pump-off results tells you what kind of leak to suspect: pump-on-only loss points at pressure-side plumbing; equal loss both ways points at the shell, fittings, or a suction-side problem.
6. Write the numbers down. A leak tech’s first questions are how much you are losing per day and whether it changes with the pump. Arriving with real numbers can shorten (and cheapen) the detection visit.

Two practical notes. Keep swimmers, backwashing, and the autofill out of the test window -- each one wrecks the measurement. And if the weather turns (a monsoon downpour, a windstorm), just rerun it; the test costs nothing.

Running the test in monsoon season

July through September complicates the measurement from both directions: an afternoon storm adds water to pool and bucket alike (fine for the comparison, ruinous for your absolute numbers), while the wind that precedes it can spike evaporation past even the peak-summer baseline. The test still works -- the bucket and pool share whatever the sky does -- but the cleanest read comes from picking a stretch with no rain in the forecast, keeping the 24-hour windows consistent, and trusting the difference between bucket and pool rather than the raw drop. If a storm lands mid-test, rerun it; two clean days beat one contaminated week.

Reading the result

Pool and bucket dropped the same amount: evaporation. In summer, a cover cuts the loss dramatically; otherwise this is just the cost of an uncovered pool in the desert.

Pool dropped more, but only with the pump running: suspect the pressure side -- the plumbing after the pump that carries water back to the pool. Underground return-line leaks behave exactly like this, and they are the ones worth professional detection gear, because the alternative is guess-digging. Repair once a leak is found typically runs $500–$1,500.

Pool dropped more with the pump on and off: suspect the shell, fittings, skimmer, lights, or suction-side plumbing. One cheap localization trick: let the level keep falling (within reason -- keep water above the main drain). A leak in a wall fitting or crack stops losing water when the level reaches it; a leak that continues all the way down is in the floor or main drain area.

Where pools usually leak

Knowing the usual suspects helps you read the bucket-test result and sanity-check a repair quote. The skimmer-to-shell joint is the single most common leak point in a gunite pool -- the skimmer is plumbed rigid while the shell and deck move independently, and the seam between them opens hairline-fine. It leaks only down to the bottom of the skimmer throat, which is why the falling-level trick localizes it. The light niche leaks through the cord conduit rather than the fixture itself -- water follows the cable out the back. Return and cleaner fittings loosen and let water past their threads. Tile-line cracks follow the waterline where sun and chemistry work hardest, and usually announce themselves visually before they leak badly. And on the equipment pad, unions, pump seals, and valve stems leak in plain sight -- the cheapest kind to find, which is why a slow walk around the pad with dry hands belongs in any leak hunt before anyone prices underground detection.

The expensive end of the spectrum -- underground plumbing and main drain leaks -- is real but less common than the fittings above. That ordering is worth remembering when a first quote jumps straight to excavation.

The other tells

Beyond the waterline: chemical demand that will not settle (constant dilution from fill water resets your balance), a green tinge despite normal dosing, air bubbles in the pump basket or blowing from returns (suction-side air usually means a suction-side leak), soggy or unusually green spots near pool plumbing runs, and cracks or settling in the deck. Autofill pools deserve special suspicion -- the device exists to hide falling water levels, so the first symptom is often a water bill, not a waterline. If the pump itself is dripping where the motor meets the wet end, that is a shaft-seal problem -- covered separately in our pool pump troubleshooting guide.

What waiting costs

A modest leak is easy to deprioritize -- the autofill keeps the waterline pretty, and summer makes any loss look like weather. But the meter runs in four currencies at once. Water: hundreds of gallons a week beyond the evaporation baseline, on desert water rates. Chemicals: every replaced gallon arrives unbalanced and untreated, so a leaking pool eats sanitizer and balancers faster (if your chemistry never seems to hold, revisit the cloudy-water guide's dilution note with fresh suspicion). Structure: water escaping underground doesn't disappear -- it saturates and moves the soil under decks and shells, and settled, cracked decking costs multiples of any leak repair. And in Kingman specifically, winter: ground kept wet by a slow leak freezes, and freeze-thaw cycling turns hairline problems into structural ones. A leak confirmed in fall is worth fixing before the first hard freeze, not after.

When to hand it off

The bucket test and the observations above are the useful end of DIY. Actually locating a confirmed leak -- pressure-isolating plumbing runs, listening gear, dye-testing fittings -- is equipment work, and in Arizona, repair and equipment work on a pool requires an ROC-licensed contractor, which is exactly what we route those requests to. Professional detection typically runs $100–$1,000 depending on pool type and how hard the leak hides; the full numbers, and what each repair type tends to cost, are on the Kingman pool leak detection page. For what normal service costs beyond leaks, see the Kingman pool cleaning cost guide.