How to Clean a Hot Tub That Has Been Sitting Empty: 10 Easy Steps

Jennifer Rhodes

By Jennifer Rhodes · Updated

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Proper maintenance is crucial for keeping any hot tub functioning properly. But what if you've let yours sit empty for a little too long? Or perhaps you just moved to a new place with a hot tub that's clearly not been used in a while, and you want to know if you can bring it back to life?

Cleaning an empty hot tub that has been sitting for some time can be a daunting task, but with the right process, it can usually be done.

In this blog post, I will guide you through 10 simple steps to clean a hot tub that has been sitting empty, even for years. From getting the pipes clean to checking the cover and exterior, I will cover everything you need to know to get that hot tub sparkling clean and ready for use again.

1. Fill and heat the hot tub

If the hot tub looks dirty on the parts you can see, you can be sure there is buildup or debris that will have accumulated during the time the hot tub was not in use on the inside too.

Filling the hot tub as the first step is necessary because it will allows for the grime and buildup in the pipes to loosen up—and be fully removed in a later step. Heating the water is also necessary to ensure the sanitizer we are going to add will work properly.

This step is very important: if you skip it, you won't be able to get the spa properly clean.

2. Test the pH and get it within 7.2-7.8

Getting the pH within the recommended range of 7.2-7.8 is necessary for the sanitizer we are going to add in the next step to work effectively.

The pH level can change the effectiveness of the sanitizer, so it's important to test the pH first:

Poolmaster 22212 Smart 6-Way Swimming Pool and Spa Water Chemistry Test Strips
Poolmaster 22212 Smart 6-Way Swimming Pool and Spa Water Chemistry Test Strips
View on Amazon

The you will need to adjust it as necessary, using pH Increaser or Decreaser depending on which way you need to go.

3. Shock the spa with a high dose of sanitizer

Adding a high dose of sanitizer at this stage is to kill any bacteria or harmful microorganisms that may have accumulated in the hot tub. Sanitizers work to kill bacteria and other pathogens, helping to ensure the hot tub water is safe and clean for use.

You can use either chlorine granules here, or a few fluid ounces of regular 6% unscented bleach. The goal here is not to get the water safe to bathe in, but so that it will kill any bacteria in the next step.

4. Flush the lines

Using a line flush like Ahh-Some will help to dislodge all the grime and buildup from inside the pipes. This type of product is specially formulated to clean the hot tub's plumbing system and remove any debris or buildup that may have accumulated over time:

Ahh-Some Premium Hot Tub Cleaner/Jetted Bath Plumbing and Jet Cleaner for Jetted Tub - Purges 400 Gallon Water Tub 4 Times (2 Oz)
Ahh-Some Premium Hot Tub Cleaner/Jetted Bath Plumbing and Jet Cleaner for Jetted Tub - Purges 400 Gallon Water Tub 4 Times (2 Oz)
View on Amazon

The product works by circulating through the pipes and breaking up the grime and buildup, making it easier to remove. This step is crucial in ensuring the hot tub's plumbing system is thoroughly cleaned and free of any biofilm growing where you can't see it.

I have a thorough post on exactly how to perform a line flush if you are not sure.

5. Drain the hot tub

Now it is time to drain the water, and get rid of that initial round of gunk. If the hot tub was very dirty, you may want to repeat steps 1-5 just to be sure you have removed all traces of bacteria.

The danger is that if you haven't managed to remove everything growing in the pipes, it will come right back once you fill the hot tub again, and make it very difficult to keep the water clean and balanced.

6. Clean the shell and jets thoroughly

Now that you've cleaned inside the pipes, it's time to clean the parts of the interior you can see. You'll want a soft brush or cloth for this.

You can either use a bleach solution or a cleaning spray like this one:

Spa Cleaner & Hot Tub Cleaner Spray - MAV AquaDoc 16oz
Spa Cleaner & Hot Tub Cleaner Spray - MAV AquaDoc 16oz
View on Amazon

Pay extra attention to areas where dirt likes to accumulate, like around the jets or the waterline. If the jets unscrew, you can even take these off and soak them separately overnight.

7. Rinse thoroughly with water

Rinsing the thoroughly with fresh water after cleaning the interior is important to remove any residual cleaning solution or debris. Cleaning solutions can leave a residue that could interact with the chemicals you will need to add later.

Additionally, you want to ensure that all traces of the cleaning solution are removed to avoid any skin irritation or other adverse effects when using the hot tub. Rinsing with fresh water is the final step in getting the actual hot tub itself clean and ready for use. You're almost there!

8. Get a new filter

If the hot tub has been sitting harboring dirt, chances are the filter has been too. It's safest to replace the old filter in this situation and just start fresh with a new one, for a few reasons:

  1. Old or worn-out filters are likely clogged with debris, affecting their ability to properly filter the water.
  2. Using a new filter will ensure that the filter itself cannot reintroduce contaminants, undoing all your hard work.
  3. A new filter should also improve the hot tub's circulation and overall performance.

In short, replacing the filter after cleaning an empty hot tub will give you the best chance of success in getting the spa up and running again. This whole process is a lot of work, so don't waste it by reusing an old or dirty filter.

9. Clean and disinfect the cover

Aside from the tub itself, it's also important to clean the cover when resurrecting a hot tub that has been sitting empty. This is because the cover can also accumulate dirt, mold, and debris while the hot tub is not in use.

What's more, if the hot tub has been sitting empty for an extended period of time, the cover may have begun to degrade due to exposure to the elements too. Inspecting the cover for any signs of wear and tear is going to be necessary for maintaining its effectiveness.

If you see any signs of damage or notice a bad smell coming from the cover, it's best to consider replacing the cover with a new one. It's not cheap, but a leaky cover will let dirt in and heat out, costing you a bunch of time and money in the long run.

If the cover looks in good condition however, you can just air it out and clean it with a mild bleach solution.

10. Clean and re-stain or paint the exterior if necessary

So that's the interior and the cover taken care of. Now the only thing holding your hot tub back is the outside!

Over time, hot tub cabinets can get faded and dirty, but the good news is you can often give them a new lease of life. I won't go into detail here on exactly how to do that here because I have a much more thorough guide on how to refinish an old hot tub cabinet in another post.

Once that's done, you are ready to fill your "new" hot tub!

Next steps

  • Now you're ready to fill your newly clean hot tub, learn about the best way to add water to it without contaminating it again.
  • Hot tub chemicals are designed to work in hot water, so you need to wait for the water to heat up so you know the chemicals will be effective. Here are some tips for how to speed up that process.
  • If you're new to hot tub care, you are going to need chemicals. My post on the best hot tub chemical starter kit has all the information you will need—including how to balance your hot tub once it's filled and heated.

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