Hot Tub Running Costs in the UK: What You'll Actually Pay For

A hot tub’s running costs are made up of more than its energy use. You’ll also need to account for water treatment, refills and occasional maintenance. The biggest variable is usually how the tub is heated: with electricity or a wood-fired stove.

There isn’t one reliable monthly figure for every hot tub. Size, insulation, weather, water temperature and how often you use it all make a difference. The Energy Saving Trust estimates that hot tubs can cost around £2 to £8 per use, depending on factors such as size, insulation and location. Treat that as a broad guide rather than a quote for a particular model. (Energy Saving Trust)

1. Heating: electricity or firewood

Electric heating and heat pumps

An electrically heated tub uses electricity to warm the water. Some systems also use electricity for circulation, filtration or a separate filter. The total depends on the tub and how it is operated.

Your tariff matters too. Ofgem’s average Direct Debit electricity rate for Great Britain is 26.32p per kWh from 1 October to 31 December 2026. Your own rate can differ by region, payment method and tariff. With a multi-rate tariff, electricity may cost less during off-peak hours. (Ofgem)

For a rough estimate, multiply the tub’s electricity use in kilowatt-hours by your own unit rate. For example, if a tub used 5 kWh in a day, at 26.32p per kWh that would be about £1.32 for that day. This is an illustration, not a typical-use estimate: actual consumption can be higher or lower.

A heater’s advertised kilowatt rating describes its power, not how many kilowatt-hours it will use over a day or month. For example, Birchwells lists a 7kW heat pump; that rating alone isn’t enough to calculate a running cost. (Birchwells hot tubs)

Wood-fired heating

With a wood-fired tub, the main heating cost is the firewood you burn. How much you use depends on the tub’s size, the starting water temperature, the weather and how often you heat it. The price will depend on your local supplier and the type and quality of wood.

Birchwells recommends kiln-dried firewood for its stoves and says they use wood only. That means the heating bill is measured in fuel rather than electricity, although any separate electrical equipment will still use power. (Birchwells hot tubs)

2. Water treatment and filtration

Hot tub water needs regular care. Depending on the system, you’ll need sanitiser, testing products and filter supplies. A sand filter can capture particles and help keep the water clear, but it does not replace water treatment or periodic water changes. BISHTA recommends changing hot tub water ideally every month, or at most every three months; always follow the guidance for your particular tub. (BISHTA: Water Treatment)

A filter system also uses electricity to circulate water, so include that in the running cost of an electrically powered setup. Birchwells currently lists a sand filter with its heat-pump option. (Birchwells hot tubs)

Birchwells also lists a chlorine floater and a six-month chlorine supply in its product bundle. Check what’s included with the tub you’re considering, and budget for replacement supplies later. (Birchwells hot tubs)

3. Water for the initial fill and refills

Filling the tub adds to your water use. You may also need to drain and refill it periodically, following the manufacturer’s guidance and your water-care routine.

The cost depends on your water company, whether you have a meter and how much water the tub holds. If your bill includes wastewater charges, check how your provider calculates them: arrangements vary, and the cost of filling a tub won’t be the same for every household.

4. Covers, wood care and occasional upkeep

Some costs arrive as occasional purchases rather than regular monthly bills. Depending on the tub, these might include filter replacements, a replacement cover, small repairs or products to care for the wood.

Birchwells says its wooden tubs need an initial treatment with oil after the wood has swollen, followed by yearly coats. Allow for that in your longer-term budget. (Birchwells hot tubs)

What can affect the total?

A few practical choices can make a noticeable difference:

• Choose a size that suits how you’ll use it. A smaller volume of water generally needs less energy to heat
• Use the cover whenever the tub isn’t in use. The Energy Saving Trust recommends a good insulated cover to reduce heat loss
• Think about where the tub will sit. A more sheltered spot can help reduce exposure to wind and cold
• Compare heating options in the context of your routine. An electric heat pump and a wood-fired stove have different costs and suit different preferences
• Check your own tariff and water bill. National averages can help with a rough estimate, but your household rates are more useful for budgeting

A simple way to budget

To estimate your own running costs, list the expenses separately:

1. Estimate the tub’s electricity use or the firewood you expect to burn.

2. Add water treatment and filter supplies.

3. Include water for filling and future refills.

4. Set aside a little for wood treatment and occasional replacement parts.

The result will be more useful than a single headline figure because it reflects your tub, your tariff and how you plan to use it. Birchwells offers both wood-fired and heat-pump options, so it’s worth comparing the setup that best fits your garden and routine. (Birchwells hot tubs)