Spa losing water
Why is my spa losing water faster than the pool?
An attached spa that drops faster than the pool it shares equipment with usually has a leak of its own, most often at the spillway, a jet fitting, or the diverter valve that switches the system between spa and pool. A spa is a small body of water with a lot of fittings in it, so the same size of fault shows there days before it would be noticed in the pool.
What it usually is
Small surface, many fittings
A spa losing water faster than the pool usually means the loss is in the spa itself rather than in the shared system.
Evaporation works on surface area, so the spa should lose less than the pool, not more. When the smaller body of water drops faster, the arithmetic already points away from the weather.
A spa packs more penetrations into less shell than a pool: a ring of jets, one or two suction fittings, an air channel, a light, and on a raised spa a spillway carrying water over the wall. Every one is a joint between something manufactured and something poured.
Be honest about it
What it could be instead
Several honest explanations put a spa lower than the pool and need no repair:
- The system is doing it on purpose. Many pool and spa combinations equalise by design, and the spa rests below its rim between uses.
- The cover, or the lack of one. A hot spa left uncovered evaporates far faster than a cool pool.
- Use. Four people getting out of a spa carry away a noticeable share of a small volume.
Narrowing it down
Where a spa loses water, and how it shows
| What you notice | Likely cause | What to check first |
|---|---|---|
| Drops to just below the spillway lip, then stops | The spillway or weir | Mark that height, then look at the grout along the lip |
| Drops steadily whatever the level | A jet, the light niche or a suction fitting | Feel around each fitting with the system off |
| Falls only while the system runs in pool mode | The diverter valve or shared plumbing | Whether the valve handle reaches its stop |
Ten minutes, on your own
Ten minutes with a cover and a marker
Note the height the spa stops falling to
Water stops leaving at the level of the hole, so where it settles is roughly where the fault is. It is the most useful fact about a spa leak.
Check the diverter valve reaches its stop
Turn it firmly to pool, then to spa. A handle stopping short of either explains a lot.
Cover the spa and leave it a day
A covered spa barely evaporates. If it still drops with the equipment off, it is not the weather.
Look along the spillway in low light
Late sun across the wall face shows missing grout, a damp band, and mineral lines where water has run outside its channel.
How urgent is it
Low urgency, one exception
A spa losing water is not an emergency. It is a small volume, it is contained, and it will wait a week.
The exception is a raised spa sharing a wall with the house or a retaining structure, because water escaping into the fill behind a raised shell has somewhere to go. A wall face that is permanently damp rather than damp only while the spillway runs is the more urgent version. If the spa has a heater, keep the water above the suction fittings.
If you call us
How a spa gets tested
The spa is isolated from the pool so the two stop being one system, then its lines are pressure tested individually, jets and suction and any air line, exactly as a pool is. A leak in shared plumbing and a leak at a jet look identical from the deck and completely different on a gauge.
Dye at the fittings, the light and along the spillway lip with the system off shows where water crosses the shell, and acoustic listening picks up the buried run if the gauge points there. Where it turns out to be the spillway rather than the plumbing, that is a structural repair and we will say so plainly: pool and spa leak detection.
Straight answers
Spa water-loss questions
Is it normal for a spa to sit lower than the pool?
Between uses, often yes. Many pool and spa combinations equalise by design and the spa rests below its rim. What is not normal is a spa that keeps falling below that resting level day after day.
Why would a small spa lose water faster than a large pool?
Because a leak does not care about surface area but evaporation does, and a spa has far more fittings per square foot of shell than a pool.
The spa drops to the same height every time and stops. What does that mean?
That the fault is at roughly that height, because water stops leaving once the level falls below the hole. Mark it before anybody arrives; it is the best clue on the spa.
Could the diverter valve be the whole problem?
It often is. A valve that does not seat fully passes water between spa and pool on the pump schedule, which looks exactly like a leak. Turn it firmly to each position and see whether it reaches its stop.
Spas we work on
Tell us what the water is doing
The height the spa stops falling to, whether the cover was on, and which position the diverter valve was in.
Send a photo of the spillway
The spa, the spillway lip and the diverter valve. Usually enough to tell us where to start.
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What customers in the Phoenix valley have written. The words are theirs, on listings we cannot edit.
“Humberto has been amazing! Prompt, professional, and patient. He has gone above and beyond, taking the time to show me how to operate the water valves and educating me so I can continue to monitor for future leaks. He identified multiple leaks and made thoughtful recommendations.”
“Beto was very professional, thorough and patient in explaining everything he was doing and why. It was an excellent and well worth it experience, and this is saying something for an architect who had a hundred questions!”
“The owner and operator of this company is everything a contractor should be. On time, honest, competent, reachable, comprehensive. Hope to work with him again in the future.”