Hot Tub Losing Water? A Practical First Step for Small Leaks Using Fix A Leak

Last updated: April 2026 · Reading time: approx. 6 minutes · Author: Xavier Labelle

Losing water from your hot tub is more than just an inconvenience. Left unchecked, even a slow leak can lead to bigger problems over time. If your water level keeps dropping, damp patches are forming around the spa, or water is seeping out from the cabinet, there's a good chance you have a leak somewhere in the system.

In this guide we'll walk you through how to assess the issue first, the spots worth checking, and how Fix A Leak can be used as a practical first step for small, slow leaks.

In a nutshell

Fix A Leak is a concentrated sealant designed for small, slow leaks in hot tubs and spas. It's added straight to the water and circulates through the system — no dismantling required. For heavy water loss or structural damage, a technical inspection is needed.

At a glance

• Slow water loss can often be treated yourself with Fix A Leak
• Before applying: try to narrow down the leak location and document it
• Remove cartridge filters before treatment
• For heavy leaks or larger damage: a professional inspection is the right call

How do you spot a leak in your hot tub?

Before reaching for a repair product, take a moment to confirm you actually have a leak and try to work out roughly where it is. A small drop in water level can simply be down to evaporation. But if you're topping up regularly, or water is pooling in specific spots, it's worth a closer look.

Typical signs of a leak

• Water level dropping faster than usual
• Wet patches or puddles forming around the hot tub
• Water escaping from underneath or through the insulation
• Needing to top up the spa unusually often

1. Gauge the water loss

Watch how quickly the water is escaping. A rapid drop usually points to a more serious issue, while a slow drip is more likely a minor leak. Mark the water level and check it again 24 hours later.

2. Check the obvious spots first

• Drain valve: is it fully closed?
• Pipework joints: any damp patches or drips on visible pipes?
• Pump area: are seals or fittings leaking?
• Underside: any standing water or persistent damp?

3. Document what you find

Photos of the affected area help you track down the cause and make any follow-up questions much easier to answer.

Note: If water loss is severe or there's larger damage, sealing alone won't be enough — you'll want a closer inspection of the spa. Fix A Leak is best suited as a practical solution for smaller, slow leaks.

What is Fix A Leak?

Fix A Leak is a concentrated sealant developed specifically for minor leaks in spas and hot tubs. The product is added directly to the water (or into the filter housing) and then circulates through the system, sealing small leak points from the inside.

For many hot tub owners, Fix A Leak is a useful first step when water loss isn't dramatic and you'd like to try a simple fix before dismantling anything or calling out an engineer.

Which leaks is Fix A Leak suitable for?

Fix A Leak is designed for smaller leaks. If your hot tub is losing water slowly and there's no visible structural damage, it's a sensible product to try.

Suitable for	Not ideal for
Small, slow leaks	Heavy water loss in a short space of time
Hairline leaks in pipework or joints	Larger structural damage
A first repair attempt before bigger work	Faulty components that need replacing

How to apply Fix A Leak: step by step

If you decide to use Fix A Leak, work through it methodically. That gives the product the best chance to circulate evenly through the system.

Preparation

• Check the water temperature
• Shake the bottle thoroughly
• Remove the cartridge filter before treatment

1. Add the product: pour the contents of the bottle into the filter housing or directly into the water.
2. Run the pump: let the water circulate for several hours so the sealant can spread through the system.
3. Observe: check whether the water loss is slowing down.
4. Repeat if needed: for stubborn small leaks, a second treatment can help.

Note: After treatment, clean the filter and refit it. If you're still seeing significant water loss, the leak needs a closer look.

The benefits of Fix A Leak

The biggest plus with Fix A Leak is how straightforward it is. No tools, no dismantling and no engineer required — the product does its job through the spa's own circulation.

• Simple to apply, with no dismantling involved
• A practical solution for small leak points
• Lets you tackle the first repair step yourself
• A sensible starting point before any bigger work
• Helps get your hot tub back up and running sooner

Frequently asked questions

How long does Fix A Leak take to work?

In most cases, you'll see initial results after several hours of circulation. For stubborn leaks, it can be worth repeating the treatment after 24 to 48 hours and continuing to monitor the water level.

Is Fix A Leak suitable for larger leaks?

No. Fix A Leak is intended only for small, slow leaks. For heavy water loss, cracked pipework or damaged components, you'll need a technical inspection. The product isn't a substitute for proper structural repairs.

Do I need to change the water after treatment?

An immediate water change isn't strictly necessary. The important step is to clean the cartridge filter thoroughly after treatment and refit it. Keep an eye on the water level and water quality over the following days.

Buy Fix A Leak for small hot tub leaks

Our recommendation: Fix A Leak is a tried-and-tested first step for small leaks. It's easy to apply, requires no dismantling, and can help get your hot tub back in action faster.

Available on our UK website:

• Fix A Leak 230ml — for small spas and minor leaks
• Fix A Leak 1L — for larger spas or repeat treatments

How much to use

The product label gives the dose as 115 ml per 950 litres. Fix A Leak seals holes up to about 3 mm across.

Spa volume	Approximate dose	Bottle
700 litres	About 85 ml	230 ml
1,000 litres	About 120 ml	230 ml
1,300 litres	About 160 ml	230 ml
Swim spa, 8,000 litres and up	About 970 ml or more	1 litre, or more than one

Your spa's volume is in the owner's manual or on the product page.

Detailed method from the product instructions

1. Shake the bottle well.
2. Remove the filter cartridge, or bypass the filter.
3. With the pump running, pour Fix A Leak in slowly in front of a suction point, such as the skimmer.
4. It is heavy and sinks quickly, so stir it back into the water every 4 to 6 hours while the water keeps circulating.
5. Keep circulating until the leak stops.
6. Once the leak has stopped, allow 24 to 48 hours for the seal to cure, then go back to normal filtration.
7. Rinse the filter clean with water. Do not let it dry out before cleaning it.

If your spa is foam insulated and has been leaking for a long time, the instructions advise draining the spa once the leak has stopped, wiping it down with a soft wet cloth, and letting it dry for 4 to 5 days so the sealer can cure properly.

When it is likely to help, and when it won't

Situation	Fix A Leak?	Better next step
Slow loss, no visible drip, under about 3 mm	Worth trying	Monitor the water level for a week
Drip from a union or fitting nut on the pump	Unlikely	Switch off and check the fitting or seal
Water from the drain valve	No	Check it is fully closed and the cap is on
Water spraying or pooling fast	No	Switch off at the isolator and call us
Cracked shell or split pipe	No	Engineer repair

When to call an engineer

• The water level drops more than a few centimetres a day.
• Water is near the control box or any electrical part. Switch off at the isolator first.
• Two treatments have not slowed the leak.
• You can see a crack or a split pipe.

Our team can help on 01293 824094 or through hot tub servicing. For finding the source, read our guide on locating a hot tub leak.

Telling a leak from evaporation

A bucket test helps. Put a bucket of water on the spa step, mark both water levels, and leave the jets off and the cover off for 24 hours. If the spa drops much more than the bucket, you probably have a leak. Repeat with the pump running: if the loss is bigger, the leak is more likely to be in the pressure side of the plumbing.