What’s the monthly cost to run a hot tub in the UK?

If you’re in the market for a hot tub, there’s a good chance you’re considering all the factors regarding what this will cost you on an ongoing basis.

After you figured out the initial spend on the hot tub, you’re likely asking, “what’s going to be the monthly cost to run this hot tub?”

At Hydropool, we want our customers to know everything they need to before they buy, which is why we wrote this article to break down the ongoing operating costs. There’s no point in dropping a hot tub in your garden if you can’t pay the monthly bills that come with it, after all. 

In writing this article, it is especially important to note that in the U.K., and across Europe, energy prices have increased in recent years. Energy costs have traditionally been closer to £1 a day, for both power and cleaning when owning a hot tub. So the monthly cost of a hot tub in the UK has gone up.

The current answer to the average running cost of a hot tub in the U.K., including power and cleaning, is about £85 a month, with about £75 of that coming from the current cost of power.  

It’s important to note: This is an average. Your price may be more or less than this and we encourage working with a local retailer to determine the costs in your area.

There are many factors that come into play here, which we will go over in this article and that price will vary depending on where you live. 

How much does it cost to heat a hot tub?

Here’s how much the average hot tub electrical bill increases in the U.K. right now with the high energy costs we all have been paying: Around £2.50 per day. 

How come it’s an approximate?

It’s because “How much will my energy bill be affected” is one of those “but it depends” questions that keep coming up with hot tubs. Here are some of the factors that come into play in your effort to save money on your tub running costs: 

  • Where you live and the temperatures there
  • Energy usage and the rate being charged for energy
  • What you keep your water temperature at
  • How the tub is built and especially how it is foam insulated
  • How often the hot tub cover is opened
  • The typical ambient temperature, the colder it is, the more it will cost
  • How often you use the tub and for how long. These two are usually the two most significant factors that determine ongoing costs, wherever you live.
  • Whether you need to run the heat all summer to heat the water or can turn it down
  • If you have an energy efficient hot tub
  • How often the cover is off the tub in any season, and the quality of that cover
  • What size of a hot tub are you getting and what power accessories go with it

Let’s have a closer look at your ongoing energy costs. 

What’s the biggest factor in your ongoing hot tub energy costs?

The biggest factor is actually you.

If you use your hot tub more, it will cost you more. In that sense, it is no different than any appliance you own. If you wash your clothes more often, it will cost you more than if you don’t.

One way to think about it is that there is one cost to maintain the temperature of your hot tub and another to using it. For example:

  • Maintaining a hot tub’s temperature is dependent on ambient temperature, the quality of the insulation and if the residual motor heat is being used to help warm your water (Hydropool does this by using an insulated blanket around the hot tub that traps the warm air within the cabinet, similar to how a tripled-paned window works. We’re based in Canada: our hot tubs have to be well-insulated!)
    • On average, the cost to maintain a Hydropool hot tub at a consistent heat is £1.26 across our range, according to California Energy Commission, which tracks such numbers (at 28p per kw per hour).
  • Added to that is the cost of running the pumps to operate your massaging jets. That cost is an additional 56p per hour on a single pump and £1.12 on a twin pump spa.

With that math, if you use your hot tub for an hour a week, your cost per month would actually be closer to £2.16 a day, meaning your monthly energy cost would drop to £65 a month.

We upped the estimated cost to £75 because hear from our customers that they that’s about what they are paying. The CEC calculates its number under strict conditions and consistent ambient temperatures, without the lid being lifted, while we know the weather changes month to month in reality and that no one buys a hot tub to watch it run without getting in it.

Again, £75 a month for energy costs in the UK is our best attempt at an average price you’ll pay. But you will want to talk to a local dealer to determine the pricing in your area.

How much do chemicals cost in your hot tub in the UK?

Water that sits and isn’t replaced requires a bit of effort to maintain. You could continually swap the water out of your hot tub like you do in a bathtub or keep a constant flow from a hose and be draining it at the same rate, at the same time. But it’s not very practical to do that and your water costs would balloon. So hot tubs require water maintenance. 

Let’s tackle the maths: It is roughly £35 for 5kg of 20g chlorine tabs. So 250 tablets for £35 is 14p per tablet and you’d use two or three a week or 12 a month. 

So chlorine, your sanitizer, is £2 a month. 

You will need some Ph balancer at £20 per kg and you would likely use that over three months, so £7. That means it’s about £10 a month for sanitizing. 

The cost of sanitizing and balancing your hot tub a hot tub is generally around £10 a month. Some people also buy things like vacuums to remove debris or a skimmer for ongoing cleaning, with a one-time cost of around £100.  

Why do hot tubs need to be cleaned at all? 

Because everything loves warm water! When people get in the tub, chemicals like deodorant, perfume, and hairspray can get washed off bodies and into the tub. Organic matter such as dirt, leaves and bugs also can end up in there when the top is off. Algae is a plant that can grow in your tub, and fungi such as mold or mildew will also thrive in warm water conditions. All this stuff needs to get out of your tub one way or another. You clean your bathroom and kitchen sink regularly for many of the same reasons. 

You require cleaning products for your tub, the same way you do for your dishes. Movement also helps your water stay fresh: Most tubs automatically circulate the water on a regular schedule (if you’ve ever been standing beside a tub and it just “comes on” this is why – it’s to engage the filters and promote cleaning). 

Here’s what you need to have on hand and why: 

  • You will want a surface cleaner or vacuum, something to skim the water with.
  • You will want test strips to check water quality once a week. A test strip will primarily monitor things like your need for chemicals such as chlorine or bromine, your water’s calcium levels which decide how hard or soft it is, alkalinity and whether your water is “in balance,” which we will explain in a second. A brand such as AquaChek makes a good test strip.
  • You need chlorine or bromine, which are both chemicals to sanitize your water. This kills any algae or mold, which both love to grow in warmed water. A healthy recommended level is between 2-4 parts per million (ppm) for chlorine and 3-5 ppm bromine.
  • Calcium is what typically makes your water hard or soft. Hard water feels oddly dry on your skin. Soft water feels nicer. But both can cause damage to your equipment over time if not kept in check. Around 150-300 parts per million is about right for calcium in your tub.
  • pH adjusters are needed so that the water doesn’t irritate your skin. pH measures whether your water is trending towards acidity or a base. Distilled water has a pH of exactly 7. If you are over a pH of 7 your water becomes a base, and below it, it becomes an acid. Why do you need to worry about this? A hot tub generally needs a pH of between 7.2 and 7.8 to feel “right.” That’s about what the pH level of your eye is. All of this to say: There are two kinds of pH adjusters as a result, one that moves pH up and another that moves it down. You’ll want some of each.

What is the cost of draining my hot tub? 

You also need to drain and re-fill your hot tub at least every quarter. Water can take care of a lot on its own, but at some point it needs a little help to wipe everything out that’s in it. Here’s a home test of what you can do to understand the issue. Let’s say you take a glass of water and put a tablespoon of sugar in it. Then another and another. Around the fourth one, it will be obvious: you won’t be able to stir it all in. It just won’t dissolve. At that point, the only way forward is to clean the water or replace it with new water. The same thing happens to your tub. If you let it go too long the water becomes saturated. 

So regular water sanitation is required, which helps keep this from happening. And the easiest way to do that is by draining. 

There’s a water cost to fill up your tub. In the UK, the cost on average 1p per liter for water. 

An average hot tub is 1000 liters, so it works out to £10 to fill. On one of Hydropool’s self-clean hot tubs, this could be done every six months, so the water cost would be around £2 a month, if you allow a little bit more each month for topping out from time to time. 

The cost of a complete flush is around £35, as you will want to use a purge product you should use it every time you drain your spa. Some people opt to pay someone to do this work for them, and the cost is usually around £300 each time.   

We included this annual cost in our monthly average maintenance bill estimate: We just want you to know where your money is going! 

How much does it cost a month to run a hot tub?

Ongoing costs are part of owning any hot tub. We want our customers at Hydropool to understand what they will be paying for once they buy a tub, all before they make any purchase, so they know how much running a hot tub costs. 

Once you get your hot tub up and running, your expenses will include: 

  • ongoing power costs to run your tub’s heater and jets
  • regular cleaning bills, which are needed due to changes that will happen to your water over time
  • Water bills, for when you need to change the water in your hot tub

Overall monthly costs average around £85 a month in the U.K. This number is fluctuating regularly, however, due to the ongoing concerns around energy costs across all of Europe. 

Given that’s the case in 2024, to get a more exact number for where you live, we recommend that you’ll want to talk to someone in your immediate area. But we hope these numbers give you a decent approximation of the costs involved as you consider making your hot tub purchase.