If you’re a hot tub owner, a leaky hot tub is probably the last thing you want to have to deal with. Fortunately, most hot tub leaks are relatively minor and can be dealt with quickly and relatively easily, if you know what to do! Today, we will explore the most common causes of hot tub leaks, and what you can do to fix them!


There are several potential sources for leaks in hot tubs. By far the most common are:

  • Rubber O-Rings, Seals and Gaskets
  • Freeze Damage

Rubber O-Rings, Seals and Gaskets

Probably the most common source of hot tub leaks comes from a rubber o-ring, seal or gasket failing. Each of these components are all designed slightly differently but all are meant for one purpose; to separate the wet areas of the hot tub from the dry areas.

Rubber is a great material to accomplish this task as it isn’t broken down by water and can be compressed with a little force to form a tight, waterproof seal between two objects.

Over time, however, the chemicals in hot tub water can break down the rubber and cause it to degrade and crack. Eventually the o-ring, seal or gasket can no longer form a tight seal and a slight leak will form. While this is usually no more than a drip at first, if left untreated the rubber will continue to degrade and the leak will get steadily worse.

Freeze Damage

The worst-case scenario for leaks is one that is caused by freeze damage. This occurs when water in the plumbing of the hot tub freezes. As water freezes, it expands. The pressure from this expansion will break unions, couplings and can even split the plumbing itself.


Finding the source of a hot tub leak is as simple as following the water. Start where you see visible water, then look for wet spots above that source. If you have a hot tub with full-foam insulation, begin removing any wet foam that you see until you find the source of the leak. Once you’ve discovered the source of the leak, it is time to fix it!


How you fix a leaky hot tub depends on what the source of the leak was. Here are a few common leak sources, and how to treat them.

Unions and Shutoff Valves

If the leak originates from a union or shutoff valve, chances are you need to replace the o-ring in the union. To confirm this you will first have to drain the hot tub. Once that is done, simply unscrew the unions and check the o-ring for damage.

If you notice that the o-ring is cracked or split in any way, replace the o-ring. If it isn’t cracked but you notice some black residue on your fingers it has likely started breaking down. You can either replace it or add a silicone lubricant to it to slow the process down and temporarily stop the leak.

If the o-ring looks completely fine you’ll want to check the union and surrounding plumbing for small cracks. If you can’t find a crack try flexing the plumbing slightly in different directions to make the cracks more obvious. Any cracked fittings or plumbing will then need to be removed and replaced.

Note: Do not use vaseline to lubricate rubber o-rings as it will actually work to break down the o-rings faster.


The process of fixing a leaking hot tub pump depends on where exactly the leak is coming from.

If the leak originates from the unions that connect the pump to the plumbing, chances are you simply need to replace the o-ring in the union. Following the same process outlined in the unions and shutoff valves section.

If the leak originates from the centre of the pump, you will likely have to replace the shaft seal. The shaft seal surrounds the shaft of the motor that spins the impeller. It is designed to prevent water in the impeller area from reaching the motor. As with o-rings and gaskets, however, it will begin to degrade over time and let water into the motor, causing it to rust and eventually seize up. If you notice a leak in the centre of your pump, you’ll want to get it repaired as quickly as possible to prevent this from happening.

Replacing the shaft seal of a hot tub pump is a complex process that requires taking the wet end of the pump completely apart. We therefore recommend seeking professional help to complete the repair.

Waterfall Valves

The process of fixing a leaky waterfall valve depends on whether or not water is getting into the cabinet of the hot tub. If the valve is visibly leaking under the handle but the foam insulation underneath is dry the repair is very minor. Start by simply removing the handle and tightening the cap underneath.

If the cap is already tight, or if tightening it doesn’t fix the leak, you will need to replace the stem assembly of the waterfall. To do this, turn off the hot tub and unscrew the cap. Once the cap is removed, pull out the stem of the waterfall valve and bring it into your local hot tub retailer for replacement. Remember to leave the hot tub powered off until you’ve put everything back together.

If water is making it into the cabinet from the waterfall valve the problem is likely either that the gasket that seals the body of the valve to the shell of the hot tub has deteriorated, or that the body of the valve itself has cracked. Either way, you will need to drain the hot tub, cut out and remove all of the wet foam insulation, then replace the entire waterfall valve.


As with waterfall valves, if there is water getting into the cabinet of the hot tub from the back of a jet, your only fix is to replace the entire jet assembly.

Freeze Damage

Fixing freeze damage is often a much more complex job with multiple issues that need to be solved. If the hot tub is leaking due to freeze damage we therefore recommend having it professionally fixed by your local hot tub retailer.


If the source of the leak isn’t obvious, or the leak simply isn’t that serious, you can try using Fix A Leak. Fix A Leak is a product that is added directly to the hot tub water with the filter removed and the pumps running. It is often able to fix minor leaks in hot tubs with 1-2 applications of around 500ml each. If Fix A Leak doesn’t fix your issue, however, we recommend that you call in the professionals to diagnose and repair the issue before it gets worse and can cause potentially serious damage to the hot tub.

The Spa Shoppe

(905) 666-5333

1545 Dundas St E
Whitby, ON L1N 2K6



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