Dec 03, 2025

What Should I Do If I think My Hot Tub is Leaking?

Do you already know you have a leak? Skip to Diagnose your leak

I'm not sure if I have a leak. How can I tell?

1. Check for common causes of water loss outside of a leak

If you leave the spa cover open, water will evaporate much faster than that of a closed cover, especially due to the high water temperature.
If people are using the spa more often than usual, the water level will go down more quickly as well, clinging to their suits and hair as they get out, in addition to the extra evaporation.
If you were away from the spa and the cover came off, you could return to a half-filled spa. Once the water evaporates a bit and the level gets low, the jets will continue to run and can shoot the water right over the side of the spa. Even with the cover on, if it doesn't seal properly, the water can run down the exterior top of the spa.

It doesn't seem to be those things, but I'm still not sure?

2. Perform the Mark-and-Measure Test

Note: if your hot tub is at risk of freezing, do NOT turn the spa off as it will not heat either.

How to do it:

Fill the hot tub to its normal operating level.
Turn the spa OFF at the breaker. (Pump, heater, and jets should all be off.) This is very important as it cuts out factors like splash out under the cover, lower water level causing jets to blow water outside of the spa, etc.
Place a piece of tape at the waterline inside the tub.
Measure the water level from the top edge to the waterline (optional but more precise).
Leave the cover Closed the entire time or you will get evaporation. If you are not able to close the cover the entire time, use the Bucket Test instead.
Wait 24 hours without using the spa.
Re-measure.

What the results mean:

0–⅛ inch drop: Normal evaporation. No leak.
⅛–½ inch drop: Heavy evaporation or minor leak—move to the next test.
More than ½ inch drop: You almost certainly have a leak.
More than 1 inch in 24 hours: Active leak that needs repair urgently.

3. Perform a “Bucket Test” to Separate Evaporation vs Leak

If you are unable to cover the spa, this test eliminates environmental factors like humidity, wind, and temperature.

How to do it:

Fill a bucket with spa water to about 4–6 inches deep.
Place the bucket on the spa step so both the bucket and tub are exposed to the same conditions.
Mark the water level inside the bucket and in the spa.
Wait 24 hours.

Interpretation:

Spa water drops more than the bucket: Leak confirmed.
Both drop the same amount: Just evaporation.
Bucket drops more: Unusual—repeat test; usually a measurement error.

Yep, I have a Leak

How do I find my spa leak?

Note: If you have water pooling in the underside of your spa, remember that water has a tendency to “run downhill”. Just because you see water at the front of the spa doesn’t mean that's where the water is coming from. It may be coming from the back of the spa and running to the front. It will be important to try to find out where the starting point is.

1. Inspect the Equipment Compartment

Most hot tub leaks originate in the equipment bay. Remove the access panel and examine:

Pump and Unions

Look around the pump unions (the large threaded connectors).
If they’re dripping, tighten them by hand—do not use tools, which can crack the fittings.
Check for worn-out O-rings; these are cheap and easy to replace.

Heater and Heater Unions

The heater assembly can leak at the unions or from pinholes in the heater tube.
Look for mineral buildup (white crust), which often indicates a slow leak.

Valves

Slice valves (the ones with pull handles) are known to leak when old.
Pressure-test by running your finger around the seams to feel for moisture.

PVC Connections

Check every glued fitting for moisture.
Small drips may show up only when the pump is running.

2. Check the Plumbing Lines

If the equipment bay is dry, the leak may be coming from one of the plumbing lines behind the cabinet.

How to Narrow It Down

Fill the tub and run the jets. Check each jet body inside the tub for drips or moisture on the exterior cabinet.
Use a flashlight. Look through gaps in the cabinet to detect wet foam or puddles.
Remove side panels. This allows you to inspect the insulation for soggy areas.

Common Leak Points

Jet housings and gaskets
Air control lines
Manifolds (where multiple lines connect)
Light lenses and seals

If your tub has full-foam insulation, locating the exact spot may take time—you’ll need to remove wet foam until you find the dripping fitting.

3. Inspect the Hot Tub Shell

Cracks in the shell are very uncommon but do happen—especially around seats or steps.

How to Check

Turn off the tub and watch for seepage from any suspicious lines running down the shell.
Hairline cracks may only leak under pressure, so inspect while the jets are running.

If you do find a crack, it’s usually repairable using:

Acrylic repair kits
Plast-Aid or similar two-part resins
Professional patching if the crack is structural

4. Dye Test for Hard-to-Find Leaks

If you have a stubborn, slow leak:

Shut off all pumps.
Use food coloring or spa leak-detection dye.
Place a few drops near suspected areas (like around jets or lights).
If the dye is pulled in, you’ve found the leak.

This method is excellent for pinpointing hairline cracks and faulty gaskets.

5. Check the Bottom Pan and Drain

Sometimes the leak is as simple as the drain valve.

Make sure the drain cap is fully tightened.
Check the hose bib (if your model has one).
Look for cracks in the bottom pan of the tub, which may collect water from other leaks.

What to do Once You Find the Leak

Depending on the source, repairs may include:

Replacing O-rings or gaskets
Tightening unions
Re-gluing PVC fittings
Replacing cracked manifolds
Patching the acrylic shell
Calling a professional for foam-embedded leaks

If the leak is small and inaccessible, a temporary leak sealant (such as Fix-A-Leak) may buy you time—though it’s rarely a permanent fix.

When to Call a Hot Tub Technician

You can call the technicians at Premier Pool & Spa at any point during the discovery or repair process and our technicians can take over from there.

You should bring in a pro if:

The tub loses more than 1–2 inches per day
The leak is inside full-foam insulation you cannot access
Electrical components may have been exposed to water
You feel unsure about handling plumbing repairs
Our coordinators won't have more in depth information than is in this article, and our technicians are in the field. If you aren't confident in finding or repairing a spa leak after reading through this, schedule a service call so we can get a technician out as quickly as possible.

Final Thoughts

Finding a leak in a hot tub often requires patience and a bit of detective work, but many common leaks are easy to track down and repair yourself. Start with the obvious spots, work methodically, and don’t be afraid to remove panels or insulation if needed. A little effort now can save you hundreds of dollars—and get you back to soaking in peace.