Restoring or Repairing a Hot Tub or Spa

Restoring or Repairing a Hot Tub

Restoring or Repairing a Hot Tub or Spa is a fun project. What I love most about what I do is the sheer variety of projects that I get to work ok. From custom new builds, to “rescue missions” where things have all gone wrong to restoring or repairing hot tubs and spas.

In this article I will try and explain some of the key steps to help you with your repair or restoration projects. I’m currently undertaking a couple of these projects with customers so that has been the inspiration for this post. Remember, I have lots of videos on all aspects of Hot Tubs and Spas on my YouTube Channel.


Restoring or Repairing a Hot Tub – Checking the Structure

Whether you have acquired an old plastic shell tub, or you have bought a new home that has a discarded in ground tub in the back yard, you are going to want to visually examine the structure.

For the plastic shell tub, open up the cabinet and have a good look inside. The older plastic shell tubs used to have a wooden structure that is holding it in place. Remember, when full of water, the tubs can hold upwards of 1000L / 220 Gallons which weighs in excess of a ton!

You need to make sure that the sub structure is going to support it. Check for any sign of rot or broken supporting beams. Of course, replace any that stand out.

For your in ground tubs, it can be a little harder to check the structure. If it protrudes at all from the ground, check the walls for cracks or signs of subsidence. If it is a concrete tub, clean it thoroughly and look for any cracks that might have appeared over time. If you can visually see them, it is best to repair them with an epoxy resin or putty before you do a water test.

Check if it is a water tight structure

The next stage is pretty straight forward, you are going to need to fill the tub and see if it can hold water. Remember, if you don’t have any control room kit connected you will need to plug any pipework that is coming out of the tub first. It is also a good idea at this point to block off any jets, drains and skimmers that are connected so you can test just the physical hot tub vessel for leaks.

Leave it overnight and see if the water drops at all. If you do find any leaks of course go ahead and repair them, it is not rocket science this step.

Checking the Plumbing

Once you have checked the structure, next step is the plumbing. Over time, if hot tubs and spas have been left and unused, then the pipework can go hard and brittle and crack. You want to be looking for any signs of this.

Look for any kind of a build up of “gunk” around any joints, this is usually an indication that there is or has been a leak. Best option here is to cut out and replace any parts that you think may be suspect.

Any union joints should be opening and the rubber gaskets inside replaced. If you can’t open them, cut them out and replace. There is no point in having a union joint with a rubber gasket that has failed, it will just leak.

How do I work out what pipe does what?

Quite often, just like one of the projects I am involved with at time of writing, the control kit has all been removed and the pipework has just been left. You need to identify what does what.

That can be pretty simple. Quick indicators – any 2” pipe work is generally water. If you have a mix of sizzes, then the smaller pipe is usually an air line. If you can physically see the pipe work then you should be able to trace it back.

You are looking for the inward suction first. This is the pipe and corresponding grills that you usually find at the bottom of your tub. These will connect the front, suction end of the pump.

If you are not sure, a great way to find out is get a hose and start filling with nothing plugged. The pipe where the water starts coming out first will be the suction side as the lower inward suction drains will be at the lowest point in the tub.

Conversely, you can always try forcing water down the pipes and seeing where it comes out. Out through the jets then you have the return or outward flow all sorted. If it appears through the drains, then this is the suction line.

If you have multiple pipes, then there will always be a suction line and a return line for each pump that was originally on the system. If the plumbing is in place, then you should see the union nuts where the pumps were originally connected, even if they have been removed.

Flush the Pipework

With the pipework identified, the next step is to get some pipe flush into the pipes to try and give them a clean. What you don’t want to do is turn them on under pressure and force all the dirt muck, dead animals etc etc onto the jets and block them all up. So, remove the jets and get some pipe flush solution into the pipework and move that round with a hose to give them a good clean.

Once the system is back up and running again, you will want to do this properly using the pump to move the flush around, but you should do this first just to get rid of any heavy debris.

Restoring or Replacing the Control Room in a Hot Tub

If the tub hasn’t been used for a long time or sold as “not working” then the chances are there is or was a problem with the control room that just was not fixed.

If you have inherited parts, I would take them off the system and look at them each individually. You will want to be replacing all the O rings and gaskets on them anyway so I would take them all off, clean them up and then follow the steps below.

Check the Pump

When you take the pump off, you should check first that it spins or turns freely. Put you hand into the impellor and check that it can rotate. Likewise, there is usually a fan on the back, check that can rotate. If it can’t it has seized and whilst it is possible to repair them, I’m more of the “just replace it” camp and for the few hundred bucks a new pump will cost, it is a lot less hassle in the long run.

I would also try putting some power to it to see if it will turn. Make sure you apply the correct voltage!

If when you add power, it trips your breaker, the coil has rusted or there is water inside it and again, if it looks old just replace it. If it looks visually ok, dry it out and try again. Worth doing this outside of the tub as it is much easier to check. Remember, don’t run the pump for too long without water!

Check the Blower

The blower is a simple piece of kit. Think of it like a hair dryer but without the heat in most cases. Heater blowers do exist, but they make no difference at all to the heat of your hot tub – they are not a contributor to the heating of your tub!

I would drop some power onto the blower to see if it works. Again, make sure you have the correct voltage. If your electric trips, the coil has rusted and gone bad or there is water in it – just like the pump.

Blowers are inexpensive so I would not bother with trying to repair them, I would just replace. When you replace the blower I would replace the check valve too – last thing you want is water in your new piece of kit.

Check the Spa Pack

The Spa Pack is the brains of the operation. I have a video here that explains all about its roles.

The first thing to check if when you put power onto the spa pack, you are getting “action” on the topside control. You should see some information on the control pad. If you get nothing, check the fuses, there are usually several in the pack and it is the smaller ones that are usually for the pack itself. The large ones are for the pumps and heater.

There should be an inlay card on the inside of the pack. Even on old tubs, these are usually in tack as they are not in the elements at all.

This will show you where to look for the fuses and what size they are. A quick check with a multi-meter will show if they are working or not – quite often some of them are too small to see with the naked eye.

The parts that generally fail on a Spa Pack are the heating elements. They are really simple an inexpensive to replace to if you look into the pack through the pipework, if the element is all rusted up then look to replace it.

Outside of this, It is worth factory resetting the pack and the configuring it from scratch. I have a post here that can help with that.

Replace the Filter

If you are trying to repair or restore a hot tub or spa, I would not bother trying to clean the old filter. Measure the size of it, google it, then buy a new one. Sub 50 bucks, not worth the hassle of an old filter that could break apart and clog up your system.

What if you need a new control room?

This is the part where I can definitely help you out. You will need to specify a pump, spa pack, blower, filter and this is certainly something I can help with.

I also have a Control Room Guide which will detain exactly how you can put all of those parts together.

Get in touch with the form below with what you are looking for.

Happy “restoration” hot tubbin’

Can I Help You?

If I can help you in any way I would love to hear from you. You can get in touch using the form below.

Thanks - Andi


Hi, Andi here. I own and also write all of the articles and info pages on the site. Some years back now, I built my own hot tub but struggled to find the information I needed. So, once my tub was complete, I started this website to help others in their own pursuit of hot tub and plunge pools DIY building information.

Today, I've helped over 1000 DIY customers just like you all over the world build hot tubs and pools. Have a good look around the site, there are lots of resources here. Please do get in touch if I can help you. - Cheers, Andi

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