Every pool in East Honolulu loses water. The only question is whether it’s losing it to the sky or to the ground.
Our trade winds and sun pull a quarter to a half inch of water out of the average pool every day. On a dry, windy week, even more. So when a homeowner calls me worried that their pool “keeps going down,” the answer is usually one of two things: completely normal, or a leak that’s been quietly running for months.
You can tell which one you have with a bucket, a piece of tape, and 24 hours. I’m Paul Costello, and I’ve been servicing pools across East Honolulu since 2000, in the business my father Jim started in 1995. This is the same test I walk clients through over the phone. It costs nothing, and it will save you from either a panic or a very expensive surprise.
How Much Water Loss Is Normal in Hawaii?
For most East Honolulu pools, normal evaporation runs 1/4 to 1/2 inch per day. That’s more than most mainland guides will tell you, and it’s why so many Hawaii homeowners suspect a leak that isn’t there.
Four things push that number up here:
Trade Winds
Wind moving across the surface is the biggest driver of evaporation. A breezy week in Hawaii Kai or Portlock can double your daily loss compared to a still one. My post on trade winds and pool chemistry covers what else that wind is doing to your water.
Strong Sun, All Year
Mainland pools get a cool season where evaporation slows down. Ours never really does. Warm water evaporates faster than cool water, and our water stays warm twelve months a year.
Heaters and Spas
A heated pool can lose noticeably more water than an unheated one, and an attached spa at 100°F loses water fast. If you just started running a heater or heat pump, expect your fill schedule to change.
Waterfalls and Splashing
Spillovers, sheer descents, and waterfalls throw water into the air, and moving air takes it. Add a few active kids doing cannonballs and some weeks you'll lose more to splash-out than to evaporation.
How much water is that? For a typical 15,000-gallon residential pool, every inch of water level is roughly 300 to 500 gallons, depending on the pool’s surface area.
So a pool dropping two or three inches over a windy week may be perfectly healthy. The only way to know for sure is to measure evaporation directly, side by side with your pool. That’s the bucket test.
The Auto-Fill Trap
Before the test, a warning for anyone with an automatic fill valve.
An auto-fill tops your pool off whenever the level drops. That’s convenient. It also means you’ll never see the water level fall, so a leak can run for months without anyone noticing. The only clue is a higher water bill, and in my experience most people don’t connect that to the pool until the damage is done.
If you have an auto-fill: Turn it off before you run any test. Then watch your water bill. If it jumped and nothing else in the house changed, the pool is the first place I'd look. A running auto-fill can hide a leak, and it also keeps pouring fresh water into the pool, which throws off your chemistry and makes the pool harder to keep clear.
The 24-Hour Bucket Test
The idea is simple. You put a bucket of pool water on the pool step so it sits in the same sun, wind, and temperature as the pool. Both lose water to evaporation at nearly the same rate. If the pool drops more than the bucket, the difference is leaving through something other than the air.
Fill to your usual operating level, around the middle of the skimmer opening. Turn off any auto-fill valve. Don't add water again until the test is over.
Use a plain bucket with no holes. Set it on a step so the bucket is mostly underwater and can't tip. If your steps are too shallow, weigh the bucket down with a few clean bricks or rocks inside.
Fill the bucket with pool water until the water inside is level with the pool water outside. Matching the levels keeps the test fair.
Put a strip of tape or a marker line on the inside of the bucket at its water level. Then mark the pool's water level on the outside of the bucket, or on the tile or skimmer face. You now have two starting lines.
Don't swim, don't add water, and don't run a waterfall any more than usual. If it rains, the test is ruined. Start over on a dry day.
Measure how far the bucket dropped from its line and how far the pool dropped from its line. Compare the two numbers.
Reading Your Results
Pool and Bucket Dropped the Same
Pool Dropped More Than the Bucket
A difference between 1/8 and 1/4 inch is a gray zone. Run the test again for another 24 hours. A real leak shows up the same way both days. A fluke doesn’t.
If it’s evaporation, you can still save a lot of water. A pool cover can cut evaporation by up to 95 percent. I cover that and other water-saving moves in my guide to a more eco-friendly pool.
Narrowing Down Where the Leak Is
Once you know you have a leak, a second test tells you roughly where it lives. It’s the same bucket test, run twice.
This is how I read the results:
| What you see | Where the leak probably is |
|---|---|
| Loses more with the pump on | Pressure side: return lines, heater, filter, or fittings after the pump |
| Loses more with the pump off | Suction side: skimmer lines or main drain lines before the pump |
| Same loss either way | The pool shell itself: a crack, the light niche, or tile line |
| Water stops dropping at a certain level | Something at that level: skimmer throat, light, or a return fitting |
That last row is the most useful clue in pool leak hunting. If you let the pool drain down on its own (with the pump off) and it stops at the bottom of the skimmer opening, the skimmer is leaking. If it stops at the pool light, the light niche is leaking. Water finds the hole and stops when it’s below it.
Try the dye test on a suspected crack: With the pump off and the water still, squeeze a few drops of food coloring or leak-detection dye right next to a crack, fitting, or light housing. If the dye gets pulled toward the spot, you've found it. It works best on a calm, windless morning.
If the leak is underground in your plumbing, you won’t find it with dye. That takes pressure testing and listening equipment, and it’s exactly what our pool leak detection service does. I explain how underground leaks work in Hawaii’s volcanic soil in my guide to pool plumbing leak repair.
Bucket test says leak?
Tell me your results and what you've seen, and I'll tell you what's most likely going on and what it takes to find it. Most leaks are faster and cheaper to fix than homeowners fear.
Call 808-399-4388Warning Signs You Have a Leak
Even without a bucket test, a leak usually leaves a trail. If you see two or more of these, test right away.
Especially with an auto-fill valve. It's often the very first sign, and the easiest to miss.
A patch of lawn that stays green and mushy during a dry spell, especially between the pool and the equipment pad, often sits right over a leaking line.
Water washing out the soil under your deck lets it sink and crack. This is the kind of damage that turns a plumbing repair into a concrete repair.
A suction-side leak pulls air in while the pump runs. You'll see bubbles in the pump lid or spitting from the return jets.
A leaking pool constantly takes on fresh fill water, which dilutes your chemicals. If you're adding far more chemicals than you used to and algae keeps coming back, water may be escaping. A pool that keeps turning green is sometimes a leak problem, not a chemistry problem.
Tiles popping off near the waterline or cracks in the shell can let water behind the finish. My guide to pool plaster damage shows which cracks matter.
What a “Small” Leak Really Costs
A leak rarely feels urgent. A half inch a day beyond evaporation doesn’t sound like much. Run the math on a typical pool.
The water isn’t even the expensive part. That 58,000 gallons is going somewhere: into the soil under your deck, your equipment pad, and sometimes your home’s foundation. On East Honolulu’s hillside lots in places like Hawaii Loa Ridge and Kalama Valley, that water can undermine a slope. Every month you wait, the repair gets bigger. My pool repair cost guide shows how fast a plumbing fix grows once the deck gets involved.
And if the pool is dropping fast, more than an inch a day, don’t wait at all. Once the water falls below the skimmer, the pump sucks air and can burn out. That’s covered in my emergency pool repair guide.
My honest advice: Run the bucket test this week. It's free and it takes one day. If it says evaporation, you can stop worrying. If it says leak, you caught it early, which is the cheapest time to fix any leak.
Let's find it before it finds your deck.
Our leak detection pinpoints where your pool is losing water, in the shell, the fittings, or underground, so you fix the right thing the first time. Family-owned since 1995, CPO certified, 5.0 on Google.
Get a Free QuoteKoko Head Pool Service provides leak detection and repair throughout East Honolulu:
Hawaii Kai · Portlock · Kahala · Diamond Head · Aina Haina · Hawaii Loa Ridge · Waialae Iki · Kalama Valley · Kuliouou · Hahaione
Call 808-399-4388 or get a free quote.
Frequently Asked Questions
How much water does a pool lose to evaporation in Hawaii?
Most East Honolulu pools lose 1/4 to 1/2 inch per day to evaporation. Windy trade-wind days, heated water, spas, and waterfalls can push that higher. Over a week, a healthy pool can easily drop two to three inches. A pool losing an inch or more per day almost always has a leak.
How do I do a bucket test on my pool?
Top off the pool and turn off any auto-fill. Set a 5-gallon bucket on a pool step, fill it with pool water to match the pool's level, and mark both water lines. Wait 24 hours without swimming, adding water, or rain. If the pool drops 1/4 inch or more than the bucket, you likely have a leak. If they drop about the same, it's evaporation.
How much water loss per day means my pool is leaking?
There's no single number, because evaporation changes with the weather. That's why the bucket test compares your pool against evaporation on the same day. As a rough guide in Hawaii, losing more than 1/2 inch a day on a calm day, or more than an inch a day on any day, is a strong sign of a leak.
Can a pool leak cause damage to my house?
Yes. Leaking water washes out the soil under your pool deck, equipment pad, and sometimes your foundation. That can cause settling, cracked concrete, and on sloped lots, erosion. Leaks also dilute your pool chemistry and can lead to algae. Catching a leak early is almost always the cheapest option.
Does homeowners insurance cover a pool leak?
It depends on your policy. Many policies cover sudden damage caused by a leak but not gradual wear or the repair of the leak itself. Check your policy or call your agent. Having a written leak detection report showing the source and cause helps with any claim.
Should I turn off my auto-fill valve?
Turn it off when you run a bucket test, and consider checking your fill frequency regularly. An auto-fill hides a leak by topping off the pool constantly, so you never see the level drop. If your water bill climbs for no clear reason, shut off the auto-fill for a day and watch the pool.
