Leaks at the top of a hot tub filter (C) Daniel FriedmanHot Tub, Spa, Whirlpool Filter Leak & Other Leak Repair
Repair leaky filters, valves, gauges, fittings at Spas, Hot Tubs & Whirlpool Baths

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Hot tub & spa or whirlpool bath leak repairs: leaks at the filter.

This article describes the repair of leaks at a hot tub or spa when traced to the filter canister or its top. We describe repairing a cracked Hayward filter dome top using epoxy - twice, and after the second repair failed, we describe replacing the top entirely.

Photo at page top: leaks at the filter dome cap of this Hayward hot tub filter occurred after the top was dropped - it cracked. An epoxy repair worked ... for a while.

This article series describes the use, operation, maintenance as well as common problems, troubleshooting, & repair suggestions for hot tubs, spas, and whirlpool baths. We discuss hot tub leaks, broken hot tub or spa jets, hot tub or spa water temperature & heater repair, hot tub or spa pump diagnosis & repair, hot tub or spa filter maintenance, cleaning & repair, noisy air pumps at hot tubs, noisy water pumps at the hot tub or spa, and other hot tub, spa or whirlpool bath diagnosis & repair topics.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

Spa / Hot Tub Filter Leak Repair - Using Epoxy to Repair Leaks at the Spa Filter Tops

Leaky spa filter cap is evident by the white deposits (C) Daniel Friedman

[Click to enlarge any image]

Above: white salts all over the filter dome top indicate a history of leaks.

Earlier we noted that on first returning this spa / hot tub to service the top of the filter unit leaked like mad. Someone had previously dropped, cracked, and repaired the top of the filter used at this hot tub / spa. But the filter top leaked badly when we turned on the spa pump, and when we set the pump to high speed water squirted into the room as if from a fire hose. We decided to try renewing the epoxy repair to the cracked filter top using epoxy.

Below: loose epoxy, indicated that the old repair was now failing and needed replacement.

Leaky dome cap top on the spa filter assembly (C) Daniel Friedman

Above: close-up of the old epoxy "repair" of the cracked spa filter dome top. The epoxy was no longer bonded to the cap and the cap leaked badly when we turned on the pump.

Below: close up showing cracks through the plastic dome in several areas. I suspect that David or Andrew dropped this cap and unfortunately it fell smack down on the air bleeder assembly. They'll deny it.

Cracked spa filter cap detail (C) Daniel Friedman

We removed the dome top, cleaned it with alcohol, used 400-grit sandpaper to lightly abrade the plastic in the area of (many) cracks around the air bleeder screw opening on both the exterior and interior of the dome, then we applied epoxy glue to the cracks on both sides of the cap. We took care not to let the epoxy drool into and block the two air bleeder openings on the underside of the cap and to keep epoxy out of the screw threads for the air bleeder screw.

Below: our next photo shows the first attempt at applying new epoxy to these old cracks.

Epoxy on the spa filter dome cap interior - take care not to block the air bleed hole (C) Daniel Friedman

The epoxy wanted to run into the air bleeder hole (blue arrow) when we applied it to the under-side of the dome cap. Repeated cleaning of the opening with at toothpick kept the air bleeder opening clear.

Below: work in process sealing the exterior of the dome cap of the strainer / filter unit for this hot tub.

Sealing leaks in the spa air filter / strainer cap (C) Daniel Friedman

Below: close up of the repaired filter dome cap.

Epoxy repair of leaky spa filter (C) Daniel Friedman

Watch out: in addition to keeping epoxy out of the two air vent openings inside the dome cap for this spa filter, we needed to avoid getting epoxy onto or into the threaded opening for the air bleeder screw. But just leaving the screw in place might risk gluing it in place. So we installed and removed it several times, wiping and monitoring its threads to be sure they were clean of glue.

Below: here is the repaired filter cap back in place.

Filter / screen unit for a hot tub or spa (C) Daniel Friedman

Damn: it still leaks, but now it just drips rather than sprays. Another pass will be needed for finding and sealing any remaining cracks in this top. Or the top dome can simply be replaced.

Checking the Hayward Star-Clear cartridge filter parts explosion ( available at SPA / HOT TUB REPAIR PARTS, SUPPLIES, SERVICES) all of the following parts are still available for this unit:

For this repair ordered a replacement filter head dome along with replacement gaskets to be delivered by mail as this was less costly and faster than ordering through a local pool equipment supplier. Below you can see the replacement filter cover in place as I check for leaks.
Also see SPA / HOT TUB REPAIR PARTS, SUPPLIES, SERVICES for help finding repair parts for your hot tub or spa or whirlpool bath.

Separately at SPA / HOT TUB FILTER REPLACEMENT you can see details of installing this new filter cover and checking the new installation for leaks.

Other Leaks at the Spa or Hot Tub Filter

Of course horrible hot tub filter leaks such as at a cracked filter canister dome top (discussed above) will be visible as water squirting all over the place. But drips can be harder to track down.

Dry off the hot tub filter to check for leaks (C) Daniel Friedman

At SPA / HOT TUB FILTER REPLACEMENT we illustrated replacing a filter cartridge followed by carefully drying off the exterior of the filter canister to inspect for leaks. That's the same procedure you'll use any time you are checking for leaks around the filter canister and its piping. Dry everything carefully, then feel with a dry finger at each fitting and connection. If your finger comes away wet, either you didn't dry thoroughly or you have found a leak.

Check for leaks at the hot tub filter air bleed screw (C) Daniel Friedman

Here are places where spa / hot tub filter leaks are common:

Hayward filter dome cap and hand screw (C) Daniel Friedman

[Click to enlarge any image]

Leak point at dome cap on a spa filter (C) Daniel Friedman

Watch out: when ordering hot tub or spa parts such as the filter canister cover be sure that you also order the necessary o-rings, seals, gaskets. Typically the filter cover is sold bare without the needed seals.

Checking for leaks around the bottom of the cap of the hot tub filter assembly (C) Daniel Friedman

Hot tub filter canister dome cap and gasket (C) Daniel Friedman

Spa filter air bleeder valve details (C) Daniel Friedman


Gauge fitting in the dome cap of a whirlpool tub filter canister cover (C) Daniel Friedman

Pipe sealant, non hardening, on a tapping seal at the dome cap of a Hayward spa filter dome cap (C) Daniel Friedman

Leaky drain valve at a hot tub or spa filter canister (C) Daniel Friedman

Leaky pressure gauge at a Hayward spa filter canister (C) Daniel Friedman

Hot tub / spa pump assembly (C) Daniel Friedman

Find & Fix Other Leaks at the Hot Tub

Other common spa or hot tub leak points include:

Signs of leak at a hot tub or spa pump impeller assembly (C) Daniel Friedman

Where the tub rim meets tile at a wall or the top of the surround, use a flexible caulk rather than grout, which will crack as the tub flexes, and expands and contracts with temperature changes.

Circulation schematic for a jetted tub © D Friedman at


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