Cold plunge running costs: what a chilled tub actually costs to run in the UK

A home cold plunge in the UK typically costs £15–£40 a month in electricity, and £250–£450 a year all in once filter cartridges, sanitiser, water and an annual service are added. The chiller is the largest single line, but it is far smaller than people expect because a chiller only works to hold a temperature it has already reached — and for a good part of the British year, the weather does most of that work for you.

The numbers below assume an electricity unit rate of 26p per kWh. That is an indicative mid-2026 figure; UK rates vary by tariff, region and payment method, and standing charges are separate. Substitute your own rate — every figure here scales linearly with it.

Where the electricity actually goes

Two things draw power continuously or near-continuously.

The chiller. A unit sized for a domestic 300–600 litre tub is usually 1/3 HP to 1 HP and draws roughly 0.5–1.5 kW while the compressor is running. The critical number is not the draw, it is the duty cycle — the fraction of the day the compressor is actually on. On a well-insulated, lidded tub held at 10°C, that ranges from close to zero in January to 40% or more during a heatwave.

The circulation pump. Typically 50–120 W. Small, but if it runs 24/7 it quietly adds up — around 20 kWh a month at 80 W continuous, or about £5.20. Many controllers let you run it on a schedule instead, and 8–12 hours a day is usually enough to keep filtration and sanitiser distribution effective.

Everything else — ozone generator, UV lamp ballast, controller — is a few watts and rounds to noise.

A worked UK year

This models a 400-litre insulated tub with a fitted lid, held at 10°C, sited in shade, with a 0.6 kW chiller and an 80 W pump running eight hours a day. Duty cycles are estimates for a typical southern-England climate.

Period	Chiller duty	Chiller kWh/mth	Pump kWh/mth	Cost/mth @ 26p
Dec–Feb	~3%	13	19	£8.30
Mar–May, Oct–Nov	~12%	52	19	£18.50
Jun–Aug	~28%	121	19	£36.40
A sustained 30°C heatwave week	~45%	(195 pro-rata)	19	£56 equivalent

Totalled across the year that is roughly 710 kWh of chiller and 230 kWh of pump — about 940 kWh, or £244 a year, averaging £20 a month. Move the same tub into direct sun, strip the insulation or leave the lid off and 1,500–1,900 kWh a year is entirely realistic, which is £390–£495.

The seasonal shape matters more than the annual total for how it feels. Nobody notices the cost in January. People notice it in July.

The rest of the running cost

Electricity is roughly half to two-thirds of the true figure. The rest:

Item	Typical UK cost	Frequency
Filter cartridge	£12–£30 each	3–6 per year (rinse weekly, replace when tired)
UV lamp (if fitted)	£40–£90	Annually — output falls long before it dies
Ozone cell/plate (if fitted)	£50–£130	Every 1–2 years
Chlorine or bromine residual	£30–£60	Per year
Test strips or a liquid kit	£15–£30	Per year
Water (metered)	~£10–£15	Per year, across 5–8 changes of ~400 L
Annual chiller service	£120–£250 if engaged out	Annually — often DIY

Call it £150–£250 a year of consumables and servicing on top of electricity. Water is almost irrelevant: at typical metered UK combined supply-and-wastewater rates of around £4.50–£5.00 per cubic metre, eight full changes of a 400-litre tub is about £15 a year. Details of what those changes involve are on the maintenance and hygiene page.

Against an ice bath’s ice bill

This is where the chiller justifies itself. Supermarket ice runs roughly £2–£3 per 2 kg bag. A 400-litre tub starting at UK mains temperature needs something like 10–20 kg to reach 10°C in winter and considerably more in summer, when mains water arrives at 18–20°C.

	Ice bath	Chilled cold plunge
Cost per session	£15–£25 in ice	~£1.60 (annual cost ÷ 156 sessions)
3 sessions/week, per year	£2,000–£3,000	£250–£450
Effort per session	20–40 min hauling and waiting	Lift the lid
Worst month	July — ice demand spikes	July — chiller works hardest

Under about one session a week, an ice bath is genuinely cheaper overall and the chiller is hard to justify. Above three a week, the ice bill exceeds the entire annual running cost of a chilled tub several times over. The chiller vs ice page works through where the crossover sits for different usage patterns, and cold plunge vs ice bath covers the wider trade-off.

The four things that actually move the number

1. A fitted, insulated lid. The single biggest lever. An uncovered tub loses heat by evaporation and radiation across its whole surface and gains it from direct sun. Keeping a close-fitting insulated cover on between sessions commonly cuts chiller run time by a third or more. A thin vinyl cover thrown over the top is not the same thing as a foam-cored lid that seals at the rim.

2. Tub insulation. Rotomoulded double-wall tubs with injected foam, or timber tubs with a foam layer behind the staves, hold temperature far better than a single-skin shell. Ask a supplier for the insulation specification, not just the word “insulated” — and check whether the plumbing runs are insulated too, because uninsulated pipework outside the tub is a surprisingly large loss path in summer.

3. Target temperature. Heat gain is proportional to the difference between water and ambient. In a 20°C garden, holding 12°C means fighting an 8°C gap; holding 6°C means fighting 14°C — roughly 75% more work for six degrees you probably do not need. Most home users settle between 8°C and 12°C for good reason, which our how cold and how long page covers.

4. Siting. A dark tub in full afternoon sun is absorbing solar gain all day. Shade — a north-facing wall, a pergola, a tree line — is free insulation. The same logic applies to the chiller itself: it needs clear airflow and should not be sitting in a hot, boxed-in corner rejecting heat into its own intake. Both points are covered in cold plunge installation, and the indoor version of the problem is on indoor vs garden.

Putting a figure on your setup

The variables that matter are tub volume, insulation quality, whether there is a real lid, your target temperature, siting and how much you pay per unit. Our cold plunge cost calculator takes those and returns an indicative install and running-cost range, rather than the single national average number that gets quoted everywhere and fits nobody.

One last point on total cost of ownership: the chiller is a refrigeration appliance with a compressor, and it will not last forever. Budget for replacement somewhere around year eight to twelve, and treat the annual condenser clean as the cheapest thing you can do to push that date further out.