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Why is Your Hot Tub Losing Water? – DIY Troubleshooting!

Written by David Stern
Last Update: August 10, 2023

No matter if your hot tub is brand-new or old, there could be leaks sooner or later for one reason or the other.

If your hot tub is losing water more than what it naturally should, there must be something wrong.

Fret not, we’re here to help!

4 Reasons Behind Your Hot Tub Losing Water: Troubleshooting

1. Evaporation

Evaporation is the most common reason for your hot tub to lose water. Generally, hot tubs lose 1 to 2 inches of water through evaporation every week. Evaporation works faster in dry climates and slower in humid climates.

Higher temperature is another reason to evaporate water faster. Always try to keep your tub temperature between 100°F to 102°F to avoid any kind of damage to the hot tub equipment.

You can also put a cover on your hot tub when not in use. It will reduce the evaporation rate and increase the lifespan of tub equipment along with improving the water quality.

2. Using the tub in wintertime

In winter, the outside temperature is much cooler than the tub’s temperature. For this, tub water will evaporate faster. It may even evaporate twice the amount of water than it does in the summer. Try covering your hot tub while it’s heating up or not in use to slow the evaporation down.

3. High use

Your hot tub will lose more water if you use it more often as the tub remains uncovered. Your swimsuits and hair also soaks up water from the tub. It can increase the amount of splashed water too.

Although it is not possible to prevent water loss during use, you can cover the tub immediately after leaving the tub to stop further evaporation.

To top off the water, use a garden hose. Remember, adding water to the hot tub every 2-3 weeks is important.

4. Leak in the tub

The final reason can be a leak in your tub which is the main discussion topic for us today. If you want to know amore about this issue and how to solve it, keep reading.

When to Look For a Leak in a Hot Tub?

The water in your hot tub may vaporize a few inches every week.

But if your tub is losing a considerable amount of water (more than 3 inches in a week), there probably is a leak.

You may see water dripping around the place where the tub is located, especially when the jets are on.

What to Do When Your Hot Tub is Losing Water?

How to locate the source of the leak and fix it?

Sometimes, finding out the base of the water losing problem in a hot tub is harder than actually fixing it. It’s nothing less than a challenge.

Method 1

Turn off the power first and detach the case paneling of the tub. Thoroughly check out every piece of equipment such as pumps, heaters, pipes, manifolds, jets, and fittings. You will notice if there are any wetness or damp spots.

Method 2

You may add food color to the tub water to locate the leaks. As your water will drain, it will leave marks in the way. Your leak detection work will be easier this way.

Note: Most of the time, tightening or loosening the gaskets and replacing the failed ones, resealing the joints, or applying waterproof PVC glue onto the cracks could solve the issue.

Method 3

Mark the water level inside with a pencil and keep the tub switched on for one day. Remember and mark how much the water level dropped.

Fill up the tub with water to the first mark, leave it turned off for one day, and mark where it dropped.

  • If the water level was equal in both conditions, perhaps your tub’s shell got a crack.
  • A significant drop with the pump switched on points toward a leak in the plumbing lines that carry water from the pump.
  • If the water drop was bigger with the pump switched off, the leak is in the pipes before your pump.

Pro tip:

Sanding down the cracked parts of the pipe before applying glue makes them stick better. If the crack on the pipe is too big, it’s a good idea to replace it with a new piece. You don’t need to replace the whole pipe, just measure the cracked part and accordingly buy a replacement.

What if There Are Leaks in a New Hot Tub?

Hot tubs eventually bring leaks. You may even find leaks in a new unit but most of the time it’s just a loose gasket.

Put it through your mind that unless you don’t have cracked plumbing lines or a damaged shell, resealing connections and replacing gaskets perfectly block the leaks in a hot tub.

Common Sources of Leaks in a Hot Tub

1. The pump

When your hot tub is losing water, you may want to take a good look at the pump first. Get a flashlight and unplug the power for inspection.

  • Seal shaft

If the shaft seal is broken, replace it with a new one. Only in rare cases do you need a replacement for the entire pump.

  • Union fitting

It’s the three-part connector at both ends of the pump. You could tighten the union fitting or adjust the o-ring.

When they’re no longer usable, replace them with your bare hands; using metal tools may harm your hot tub fittings.

  • Volute

The volute is located at the impeller case, if you have an issue with it, go for a replacement.

2. Plumbing lines

The plumbing lines hold the most potential reason for your hot tub’s water loss. PVC pipes are a big source of leaks and they crack in many ways.

Check along the backsides of your spa jets and see if there are any loose lock nuts, failed spa jet gaskets, or glued joints.

3. Lights

Hot tub light cases are typically on the same side of the spa pack. When the lenses get loose or cracked, the leak occurs.

4. Filters

If your filter rings have failed or loosened, you may want to use fresh gaskets or o-rings to deal with this issue.

5. Spa shell

Rotomolded plastic, acrylic, and vinyl are the most common materials that hot tub shells are made of. Cracks on the shell are a rare thing to see.

But if it cracks, get a thin drill bit and drill holes at the two ends of the crack to stop it from spreading first. There are tons of products available in the market to help you get this job done.

Epoxy putty and epoxy paint are the best things for shell crack repair.

6. Valves

Hot tub valves come in more than one style and each one of them is repaired differently. Be sure to check your valves and do your repair or replace accordingly.

7. Heater

A rusty heater tube bears the proof of a leak. Look for the leak in plumbing unions, pressure switches, or sensors.

The heater is a sensitive part of the tub. It’d be better if you let the professionals deal with it.

8. Jet Nozzles

Let’s not forget about the fittings and connections of the jets and nozzles. If the water only drops down to a specific level, the jets straight on top of the water line should be examined.

9. Connections

All your connections, jets, and manifolds need to be checked. A hot tub is a dense work of engineering and it can leak from tons of places.

You can use plastic repair glue or epoxy putty to repair cracked PVC pipes or seal the joints.

What if You Can’t Locate the Leak?

It’s alright if you can’t locate the leak. A hot tub could have multiple leaks as it has so many connections and components working together.

If you couldn’t find where the leaks are exactly located, you may call your local technicians to get a hot tub repair.

Note: Sometimes, it takes multiple repairs to get your hot tub perfectly fixed as it is hard to locate all the leaks (in case you have more than one leak) at once.

So, you may want to be a little more understanding with your local hot tub technician friends, and don’t be frustrated.

5 Common Hot Tub Control Panel Codes

Your hot tub control panel will display code words to tell you that something has gone wrong. They won’t necessarily explain the issue, but you’ll get a hint to start off with the troubleshooting.

1. FLO or FLC

When your hot tub has problems with flow or the jets are not acting convincingly.

Look for the blockages, get the new filters in and check your circulation pump.

2. OH

Do not use the tub when the control panel shows this sign. It indicates that the water is scalding hot that your skin cannot stand.

3. DR or DRY

It’s a sign of not having enough water in the tub. It’s a dangerous situation as it may cause dry fire from the damaged spot on the heater.

A hose filter could be the solution for this since it’ll keep filths out of your tub and plumbing lines.

The problem will persist if your circulation system has blockages when you restart your hot tub again.


You’ll see this error code on the screen when the water temperature falls 20-40 degrees down from the original set point.

Cover up your hot tub and run the heater for 24 hours. If the water is still cold after 24 hours, you may want to reset your heater, eyeball the thermostat and sensors to address the fault.

5. SNA or SNB

This abbreviation is for sensors, and the panel tells you which of your sensors is failing by showing you the letters or numbers.

This code pops up when your sensors get disconnected from the circuit board, or the circuit board is burned out.

If you don’t know much about electronics, you may want to call a pro for help.


1. How do I stop my hot tub from draining?

Ans: Turn off the spa suction valves and keep the return valves partly on. This will get the water flowing between your pool and spa which stops your hot tub from draining.

2. How often should I add water to my hot tub?

Ans: Once every 3 months, completely drain all your hot tub water and refill it with fresh water. Change your water more often if you’re using the tub a lot.

3. How often should I put chlorine in a hot tub?

Ans: At least once a week it is fine to put chlorine in your hot tub, but a good rule of thumb is to put a bit of chlorine before each time you use it, and your chlorine level should be 1.5 to 3.0 ppm.

About the author

David Stern

Despite a humble beginning at a childcare facility, David sored to success due to his inextinguishable desire for learning and a rare self-motivational disposition. The day he received his appointment letter from LANE ENGINEERING CONSULTING, P.C. was the happiest day of his life. He was trained in plumbing and fire protection systems. The firm taught him the fundamentals of waterproofing, facade restoration, mechanical and structural plumbing. His profound and innovative plumbing knowledge sets our research guidelines. He’s currently working on his new book titled “Plumbing Essentials.”

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