A hot tub is one of the larger discretionary garden purchases a UK homeowner can make — not just because of the purchase price, but because the ongoing running costs are often underestimated at the point of buying. A well-insulated acrylic spa used three or four times a week can add £60–£120 per month to your electricity bill; a poorly insulated entry-level unit running at 40°C through a British winter can push that figure considerably higher.
Types of Hot Tub
Inflatable hot tubs have transformed the entry-level market. Prices start at around £300 for a four-person unit. They are lightweight, easy to store in winter, and require only a standard 13 A socket. The trade-off is that they heat slowly (3–5 hours from cold), are not as well-insulated as rigid spas, and have a limited lifespan of 3–7 years with careful use.
Acrylic/rotational-moulded rigid spas are the mainstream choice, ranging from four-person entry models at £3,000–£5,000 to large eight-person swim-spa hybrids at £15,000–£30,000. They heat faster, retain heat far better due to full-foam or partial-foam insulation, and typically come with a 5–10-year shell warranty.
Wooden hot tubs — typically cedar or larch — appeal for their aesthetics. Prices run £2,000–£8,000. They are usually heated by a wood-fired stove mounted inside the tub and have no electrical pump system, making running costs very low once up to temperature. The downside is slow heating (2–4 hours), no filtration system, and higher maintenance.
Swim spas combine a hot tub section with a resistance swimming current. Prices start at around £10,000 and reach £40,000+ for top-specification units. They require a larger footprint (typically 5–6 m long) and more substantial electrical supply.
2026 UK Purchase Costs
| Type | Typical price range (inc. VAT) |
|---|---|
| Inflatable hot tub (4–6 person) | £300–£900 |
| Entry-level rigid spa (4 person) | £2,500–£4,500 |
| Mid-range rigid spa (5–6 person) | £5,000–£10,000 |
| Premium rigid spa (6–8 person) | £10,000–£20,000 |
| Wooden hot tub (cedar, wood-fired) | £2,000–£8,000 |
| Swim spa (5–6 m) | £10,000–£35,000 |
These prices are for supply only. Installation adds cost depending on what is required.
Installation Costs
| Item | Cost range |
|---|---|
| Concrete pad (standard 2.5×2.5 m, 100 mm) | £600–£1,200 |
| Reinforced concrete pad (heavy spa) | £900–£1,800 |
| Decking platform (pressure-treated timber) | £800–£2,500 |
| Electrical supply (32 A circuit from consumer unit) | £600–£1,200 |
| Crane lift over house (if access is restricted) | £400–£800 |
| Delivery and positioning (typical) | £100–£300 |
Most rigid spas require a 32 A dedicated circuit (some 50 A for larger units or swim spas) installed by a qualified electrician under Part P of the Building Regulations. Inflatable tubs typically run from a standard 13 A socket, though the socket should be RCD-protected and ideally on a dedicated circuit.
A concrete or paving slab base is essential — the manufacturer’s warranty is usually void if the tub is sited on soft or uneven ground. A 2.4×2.4 m spa filled with water and six adults weighs approximately 2–3 tonnes.
Monthly Running Costs
The biggest ongoing expense is electricity. UK running cost calculations use the current Ofgem-regulated energy price cap for electricity — in mid-2026 approximately 24–25p per kWh for a typical rate.
| Tub type | Insulation quality | Monthly electricity | Monthly chemicals | Total per month |
|---|---|---|---|---|
| Inflatable (4-person) | Poor | £80–£140 | £20–£35 | £100–£175 |
| Entry rigid (4-person) | Partial foam | £60–£110 | £20–£40 | £80–£150 |
| Mid-range rigid (5–6 person) | Full foam | £50–£90 | £25–£45 | £75–£135 |
| Premium rigid (6–8 person) | Full foam + insulated cover | £45–£80 | £30–£50 | £75–£130 |
| Wooden (wood-fired) | N/A | £5–£15 (pump only) | £20–£35 | £25–£50 |
Heat retention is the single biggest variable. A full-foam-insulated spa with a well-fitting hard cover typically uses 3–5 kWh per day to maintain 38°C in winter — roughly £25–£38 per month at current rates. A poorly insulated unit under the same conditions can use 8–12 kWh per day — £58–£90 per month just on standby heating.
Tips for reducing running costs:
- Keep the cover on whenever the tub is not in use — up to 70% of heat loss is through the surface
- Lower the temperature to 36°C rather than 40°C when the tub will be unused for several days; dropping 4°C saves roughly 10–15% in running costs
- Run filtration cycles during off-peak Economy 7 hours if you have that tariff
- Check and replace the cover every 4–6 years — a waterlogged cover insulates far less effectively
- Add a floating thermal blanket (£30–£80) to reduce surface heat loss further
Planning Permission
Hot tubs in rear gardens generally fall under Permitted Development in England and do not need planning permission. Check if your property is in a conservation area or if your PD rights have been removed via an Article 4 Direction.
An electrical connection to an outdoor installation must comply with Part P of the Building Regulations. A qualified electrician should sign off the work and issue a Building Regulations compliance certificate.
Maintenance Schedule
| Task | Frequency | Annual cost (approx.) |
|---|---|---|
| Water chemistry testing and dosing | Weekly | £240–£480 (chemicals) |
| Filter cartridge cleaning | Monthly | — |
| Filter cartridge replacement | Every 1–2 years | £40–£150 |
| Full drain and refill | Every 3–4 months | £15–£30 (water) |
| Hard cover replacement | Every 5–7 years | £300–£700 |
| Annual service (pump, heater, jets check) | Annually | £100–£250 |
Inflatable vs Rigid Spa: Which Is Right for You?
If you are unsure whether you will use a hot tub regularly, an inflatable model is a sensible first step — the low capital outlay limits your risk. If you use it frequently for 12 months, that is a reasonable signal that a rigid spa will pay for itself in enjoyment and lower per-use cost.
The ongoing running-cost difference between an inflatable and a mid-range rigid spa is often surprisingly small in mild months, but diverges significantly in winter. If you intend to use the tub year-round, the insulation quality of a rigid spa makes it the more economical choice over a three-to-five-year horizon despite the higher upfront cost.
