Do Hot Tubs Lose Water? (Leak or Evaporation)

With a hot tub, most of us know we have to occasionally add more water. But is that always a sign of a leak, or do hot tubs lose water?

Here’s what I know from owning 4 of them:

Hot tubs do lose water due to evaporation, but not more than 1 inch a week unless the cover is left open or it sees heavy use. A well-fitting cover can minimize water loss from evaporation. And generally the lower the water temperature, the slower the evaporation rate.

But there’s a lot more to get into about what evaporation, winterizing hot tubs, and finding and fixing leaks, so let’s keep going!

How much water do hot tubs lose?

Hot tubs typically lose about 1 inch of water per week. But it could be 2 inches or more if it’s frequently uncovered, always set to 104° F, or gets daily usage.

Lots of factors come into play with normal hot tub evaporation.

  • The temp the hot tub is set to
  • Temperature and humidity of where you live
  • The quality of your cover and how tight it fits
  • How frequently the cover is left open
  • Frequency of use and how many users

That being said, there are some baselines we can use.

Frequent use by multiple guests means both that the lid will be off frequently and there will be some water soaked into swimsuits & hair and splashed out of the tub.

Hot tub water also tends to evaporate much faster in a dryer climate compared to a humid one where there’s lots of moisture in the air. Also, the hotter you set your tub, the more prone to evaporation it will be.

Heavy use could see as much as 1-2 inches of loss each week, especially during winter.

Does hot tub water evaporate in winter?

In short, while hot tub water evaporates all year, it does tend to evaporate faster when it’s cold outside since the hot tub water is significantly warmer than the ambient air temperature.

Humidity also affects the evaporation rate, so the more humid your air, the less evaporation you will see.

So you may see twice the evaporation during winter that you see the rest of the year. Maybe even 2″ a week or greater.

Can you add water to a hot tub?

Yes. You should top off your hot tub every 1-2 weeks, or as needed. Simply run the garden hose to your hot tub, and fill it until it reaches the desired level. Then check and adjust the chemical levels when done.

In fact, if you never added water to a hot tub, it would eventually run out altogether, to say nothing of not being very pleasant to be in.

I just fill mine with a garden hose to the appropriate level and then treat with chemicals and test with my test strips to ensure they are properly balanced.

It’s also a good idea to completely change your water from time to time as well.

How often should I change my hot tub water?

Plan to change your hot tub water every 3 months. This will help ensure clean water that is free from debris, bacteria build-up, and an excess of body oils which can lead to foam.

Even treating with chemicals and changing your filters regularly, it’s still easy for your hot tub water to get dirty and oily; especially with frequent use.

You can change your hot tub’s water simply by attaching a garden hose to your hot tub’s spigot or using a submersible pump.

I like the submersible pump as it can drain my hot tub in about 15 minutes. By comparison, a garden hose may take 2 hours or more to drain.

The sooner you drain it, the sooner you can fill it back up and start heating it up, both of which can take hours.

How do I change the water in my hot tub?

To change the water in your hot tub, simply:

  1. Cut the power to your hot tub at the nearby disconnect box
  2. Locate the hose spigot on your hot tub – this is usually behind a main or corner panel
  3. Pull the spigot out – this ensures water won’t start flowing out immediately
  4. Remove the cap on the spigot
  5. Connect a garden hose to the spigot
  6. Run the other end of your garden hose to a discrete part of your yard
  7. Push the spigot on the hot tub in to start the flow of water
  8. When fully drained, use a wet/dry vac to vacuum up any remaining water on the floor or seats
  9. Wipe down the hot tub with a clean rag and a mix of 50/50 white vinegar and water
  10. Remove the hose, and replace the cap on the spigot and replace the paneling
  11. With the hose connected to your house’s hose spigot, refill the hot tub – this can take between 90 minutes and 3 hours depending on the flow rate
  12. Turn the power back on once the water level is over the intake vents on the floor of your hot tub. If you don’t have those, wait until it’s about 50% full

All hot tubs have a drain underneath the tub where your equipment is.

Unfortunately, every brand does this a little differently. My 1st hot tub had a hose spigot on the side so I just hooked up a garden hose and directed it away from the tub and could simply turn the hose knob to drain the tub.

My 2nd tub I had to open the panel (with a screwdriver) to get to the equipment and remove a large hose that had a valve on the end of it.

But using a garden hose will take 2 or more hours to drain.

You can also buy something called a submersible pump to speed up the process as it drains the tub QUICK!

My favorite sump pump to drain my hot tub is the EZ Hot Tub and Pool Submersible Drain Pump.

It has flawless reviews on Amazon and it’s an Amazon’s Choice pick. It drains 2000 gallons an hour (the average tub is about 400) and it comes with a 25′ drain hose, so you can drain it well away from your tub and house. I can drain mine in about 15 minutes with this.

CLICK HERE to check current prices on Amazon.

How do I find a leak in my hot tub?

You can find a leak in your hot tub by removing the panels and looking for water pooling on the ground. You’ll know if you have a leak when the water levels drop more than 2″ in 1 week.

There are a number of places where you can have a leak, such as:

  • Where the pump connects to the heater
  • On the other end of the heater
  • At the jets where they fit into the tub
  • In the lines that run under the tub

Unfortunately, not all of those places are easy to get to, as some of the jets will be encased on spray on foam or insulation.

Start by removing at least 1 side of the panel around your hot tub.

Some are wood and some are plastic or vinyl, and all are different, but yours should pop open relatively easily with a screwdriver or cordless drill.

Once you can see under the tub, see if you can find where the water is pooling on the ground or if you see it dripping.

Since the pipes are pumping hot water, and heat naturally causes expansion, it’s not uncommon for fixtures to come loose over time or for parts to wear out.

How do I fix leaks in my hot tub?

Water leaks often come from the union fittings between the pump & heater. First, close the gate valves to stop water flow, and remove union fittings to check for worn gaskets. But small leaks elsewhere can usually be fixed with a liquid Fix-a-Leak product within 24 hours.

But there are many other ways leaks can happen, and solutions to fix them.

You can also apply some JB Weld WaterWeld Epoxy Putty (click to see current price on Amazon) on any pipes where small holes have developed.

It is designed to apply under wet conditions and in my experience using it on my tub, it works great. Just don’t apply it to any fittings where you may later want to open or tighten them.

Lastly, I will say what has worked the best for me in fixing hot tub leaks is a product called Marlig Fix-a-Leak. Click that link to see it on Amazon.

I just remove the hot tub’s filter and pour it in where the water gets sucked in by the pump. Then let it go to work.

It’s a liquid, but it’s heavier than water so it naturally flows to wherever the lowest point it which is usually where the leak(s) is.

If you have leaks, you’ll definitely want to check out my Marlig Fix-a-Leak Review of exactly how it works, how to use it step-by-step, and see if you don’t love it as much as I do.

Just click the link to read it on my site.

Did I cover all your questions about hot tubs losing water?

In this post, we took an in-depth look at hot tubs and what causes hot tubs to lose water.

We explored normal water evaporation. But we also answered questions about how to treat your hot tub in winter, and what to do if you think you have a leak.

If you need help replacing hot tub equipment or refurbishing an older one, I’ve done just that with an old one I bought online for next to nothing.

I detail the entire process in one of my most popular posts. So check out my post on How to Fix Up a Hot Tub to learn more about just how easy it is!

Are you seeing significant water loss in your hot tub?


Photo credits (that aren’t mine or which require attribution):
Hot tub moving pictures taken from the Unique Moving & Hauling Facebook Page

Jeff Campbell

Jeff Campbell is a husband, father, martial artist, budget-master, Disney-addict, musician, hot tub lover, and recovering foodie having spent over 2 decades as a leader for Whole Foods Market.

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