A leaky hot tub is probably the last thing you want to have to deal with as a hot tub owner. 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 diagnose and fix them!

What Causes Hot Tubs To Leak?

While there are many potential sources for leaks in hot tubs, by far the most common are rubber O-rings, seals, gaskets and 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 designed slightly differently but all are meant for one purpose; to seal off the wet areas of the hot tub from the dry areas.

Rubber is an ideal material for keeping water out of dry areas as it isn’t broken down by water and can be compressed with 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 rubber will no longer form a tight seal and a slight leak will form. While this will be 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

Freeze damage occurs when water in the plumbing of the hot tub freezes. As water freezes, it expands. The pressure from this expansion can break unions and couplings; and even split the plumbing itself!

How To Find The Source Of A Hot Tub Leak

Finding the source of a hot tub leak is as simple as following the water. Start from the floor of the hot tub cabinet to see where the water is pooling, then look for wet spots or drips above it. Keep following the path of the water until you find where the leak is coming from. If you have a hot tub with full-foam insulation, you’ll need to remove any wet foam in your way as you move along the water’s path.

Once you’ve discovered the source of the leak, it is time to fix it!

How To Fix A Hot Tub Leak

How you fix a leaky hot tub will depend on the cause and location of the leak. Here are a few of the most common.

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 do 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 the o-ring looks completely fine you’ll want to check the union and the surrounding plumbing for small cracks. If you don’t see any cracks try flexing the plumbing slightly in different directions to open up any hairline cracks. Any cracked fittings or plumbing will need to be cut out and replaced.

If there are no cracks in the plumbing or fitting, try adding some silicone lubricant to the o-ring / gasket in the union or shutoff valve. This will help to form a waterproof seal around the o-ring / gasket. Do not use vaseline to do this as it will actually work to break down the rubber faster and will cause more problems to appear over time.


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. If this is the case, simply follow the same process outlined in the unions and shutoff valves section to troubleshoot and fix the leak.

If the leak originates from the centre of the pump, you will likely have to replace the pump’s 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 electric motor powering the pump. As with o-rings and gaskets, however, the shaft seal can 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 pump completely apart. For this reason we recommend seeking professional help to complete the repair.

Waterfall Valves

The process of fixing a leaky waterfall valve depends on whether if the leak originates from the top or the bottom of the valve. If the valve is visibly leaking under the handle but the foam insulation underneath is dry, the repair will be 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 can then try to replace the rubber seal that is found underneath the cap. To do this, turn off the hot tub, unscrew the cap and remove and replace the seal with a new one. Once the seal is replaced and the cap is back on the valve, you can turn the hot tub back on.

If replacing that seal doesn’t fix your leak, you will then need to replace the stem assembly of the waterfall. To do this, turn off the hot tub again and unscrew the valve 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 that the body of the valve itself has cracked. To fix this you will need to drain the hot tub, cut out and remove any wet foam insulation, then replace the entire waterfall valve.


If water is leaking into the cabinet of the hot tub from the jet housing, your only fix is to replace the entire jet assembly.

Freeze Damage

Fixing freeze damage is often a much more complex job with multiple potential 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.

Replacing Spray Foam Insulation

When fixing a leak in a hot tub that utilizes spray foam insulation you’ll likely need to cut out and remove some of that spray foam. Once the leak is fixed you’ll want to replace that insulation that you removed. Canned spray foam will work, though we recommend stuffing the area with regular fibreglass home insulation.

What If You Can’t Find The Source Of The Leak?

If the leak in your hot tub is relatively minor and you’re unable to find the source, 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.

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