What does an outdoor hot tub cost per year — electricity, water, chemistry, maintenance? Here's the full verifiable math for DE and AT 2026 with published Wellis consumption data and realistic electricity prices €0.32–€0.42/kWh (DE) and €0.22–€0.32/kWh (AT).
Three values circulate in the industry — they measure different things. To compare honestly, you need to know all three.
Mandatory EU-wide since 2021. Measured at +20 °C ambient and 38 °C water per EN 17125. Standardised and comparable across brands. Wellis Plug & Play: typically class C with Polyfoam, class B with Scandinavian upgrade. Weakness: doesn't capture DE/AT winter conditions.
The practical value. Wellis publishes two ranges: summer (+15 °C) and DE/AT winter (-10 °C), measured at the Hungarian factory laboratory. More relevant than the EU class for our climate but not third-party certified. Brands refusing this figure are a warning sign.
The only fully honest number — and it varies. An energy meter (€20–€40) on the 16 A socket measures it. Real Wellis owners report ±10% deviation from spec-sheet values. Biggest deviation drivers: cover condition and placement.
In order of impact — the first explains 30–40% difference between models, the last under 5%.
Polyfoam vs. Scandinavian full-foam: 30–40% winter consumption gap. For a Wellis Mars P&P that's ~€343/year difference. Largest structural factor — purchase-time decision, not retrofittable.
A waterlogged, sagging, or ill-fitting cover increases consumption 20–30%. Largest fast-acting lever: cover replacement (€450–€650) pays back in 2 years. Cover lifespan typically 5–7 years.
Every degree above comfort threshold costs ~5% more. 36 °C instead of 38 °C saves ~10%. During longer absence (vacation), the setpoint can be reduced via app to 30 °C — ~25% saving in vacation mode.
Privacy screen, hedge, or gazebo reduces wind-induced heat loss 5–15%. Sunny placement saves 3–8% in summer half. Smaller lever but cost-effective to add post-purchase.
Concrete tables for Mars, Callisto, Castor with Scandinavian full-foam insulation. Electricity assumptions: DE €0.32–€0.42/kWh, AT €0.22–€0.32/kWh (Q1 2026).
2,646 kWh/year (Scandinavian)
Electricity DE: €847–€1,111
Electricity AT: €582–€847
3,194 kWh/year (Scandinavian)
Electricity DE: €1,022–€1,341
Electricity AT: €703–€1,022
3,559 kWh/year (Scandinavian)
Electricity DE: €1,139–€1,495
Electricity AT: €783–€1,139
Annual full-cost view. Plus an honest comparison vs. sauna and pool.
€847–€1,495/year in DE depending on model and insulation. AT: 25–30% less. With Polyfoam instead of Scandinavian: +30–40%.
€120–€180/year. Bromine or chlorine tablets (€50–€80), pH plus/minus (€20), calcium protection (€30), foam stopper (€10), filter cleaner (€20). Higher end with hard water.
€40–€80/year. 2–3 filter changes per year; Wellis cartridge filters €15–€25 each. Cleaning between changes is free (rinse).
€15–€30/year. 3–4 complete water changes per year recommended; fresh water ~€5 per change at 1,000–1,500 L. Wastewater fee per local council.
€0–€150/year. DIY maintenance (filter cleaning, water testing, cover care) is feasible. One-off pro inspection recommended every 2 years (€120–€180). For issues, Wellis service is bookable directly via TwoRelax.
Home sauna ~€600–€900/year electricity (1×/week). Hot tub 2,646–3,559 kWh = €847–€1,495/year electricity. Medium heated pool 8,000–15,000 kWh = €3,200–€6,000/year. Hot tub sits energetically between the two, cheaper per usage hour than sauna.
Six concrete levers with quantified savings. Cover maintenance is the largest fast-acting lever — bigger than model choice.
Largest immediate lever. Waterlogged or sagging cover = +25% consumption. New Wellis cover €450–€650, payback typically 2 years.
When not actively using, set 36 instead of 38 °C. ~10% saving. App-controlled Wellis models auto-warm ~30 min before scheduled use — no comfort loss.
An additional floating film on the water surface (€20–€30 one-time) cuts evaporation heat loss ~5%. Don't use during shock-foaming.
Privacy screen, hedge, pergola, or gazebo — reduces wind-induced heat loss 8–15%. Largest placement lever in wind-exposed positions.
If you have a DE night tariff (typically €0.18–€0.25/kWh vs. €0.40 daytime), schedule the Wellis heating cycle on night hours via app. Saving: 25–40% of electricity costs.
For longer absences (>2 weeks): setpoint to 30 °C, pump to eco. ~25% saving during the absence period. Full shutdown only worth it >6 weeks because of heat-up loss.
Three models, all available with Scandinavian upgrade, all 16 A Plug & Play (no electrician).
€7200 · 3-person · 1,000 L water volume
Polyfoam: 14–18 kWh/24 h winter / 5–8 summer
Scandinavian: 9–12 kWh/24 h winter / 3–5 summer
~2,646 kWh/year (Scandinavian)
€7200 · 5-person · 1,300 L water volume
Polyfoam: 15–19 kWh/24 h winter / 6–9 summer
Scandinavian: 10–15 kWh/24 h winter / 4–6 summer
~3,194 kWh/year (Scandinavian)
€7200 · 6-person · 1,500 L water volume
Polyfoam: 16–20 kWh/24 h winter / 7–10 summer
Scandinavian: 11–16 kWh/24 h winter / 5–7 summer
~3,559 kWh/year (Scandinavian)
The most-asked questions about consumption, operating costs, and efficiency.
A modern outdoor hot tub with Scandinavian full-foam insulation consumes 3–16 kWh/24 h depending on model size and ambient temperature. Specifically: a Wellis Mars Plug & Play (3-person) with the Scandinavian upgrade sits at 3–5 kWh/24 h in summer and 9–12 kWh/24 h in DE/AT winter (-10 °C). Larger units like the Wellis Castor P&P (6-person) range 5–7 kWh/24 h summer and 11–16 kWh/24 h winter. Polyfoam-only models without the Scandinavian upgrade run 30–40% higher.
At a realistic DE electricity price of €0.32–€0.42/kWh (2026), the annual consumption of a Wellis Plug & Play with Scandinavian insulation: Mars P&P ~2,646 kWh/year = €847–€1,111 (DE) or €582–€847 (AT). Callisto P&P ~3,194 kWh/year = €1,022–€1,341 (DE). Castor P&P ~3,559 kWh/year = €1,139–€1,495 (DE). AT buyers typically pay 25–30% less due to lower electricity rates.
Four factors in order of impact: 1. Insulation (Scandinavian full-foam vs. Polyfoam = 30–40% difference). 2. Cover quality and fit (loose or damaged cover = +20–30% consumption — the biggest quickly-fixable lever). 3. Water-temperature setpoint (every degree above 38 °C costs ~5% more; 36 °C instead of 38 °C saves ~10%). 4. Ambient temperature and placement (wind protection and sun exposure reduce consumption by 5–15%). Number of uses per week has surprisingly low impact — ~3–5% per additional use.
In DE/AT climate: yes, clearly. The Scandinavian upgrade costs €1,000–€1,500 one-time at Wellis. It saves 30–40% winter electricity — for a Wellis Mars P&P that's ~€343/year in Germany. Payback period: typically 3–5 years. Over a Wellis 15–20-year lifespan, net gain is €4,000–€8,000. Plus: Scandinavian enables reliable year-round operation even at -20 °C, while Polyfoam-only models lose heating capacity and efficiency at very low ambient temperatures.
Realistic annual total operating costs for a Wellis Plug & Play with Scandinavian insulation in DE: electricity €847–€1,495 · water chemistry €120–€180 (bromine or chlorine + calcium protection + pH regulators) · filters €40–€80 (2–3× per year) · water changes €15–€30 (3–4× per year) · maintenance/service €0–€150 (DIY or once a year professional). Total: typically €1047–€1935 per year depending on model, insulation, and use. Plus possible initial electrical installation (16 A Plug & Play: €0; 32 A hardwired: €300–€800 one-time).
Yes, with measurable levers: check or replace cover (waterlogged cover = +25% consumption; a new Wellis cover costs €450–€650 and pays back in 2 years). Lower setpoint to 36–37 °C when not actively in use (~10% saving). Thermal floating blanket under the cover (additional floating film ~€25, reduces evaporation loss ~5%). Wind shelter (privacy screen, hedges, gazebo) reduces consumption 8–15%. Smart plug with night tariff (DE often €0.18–€0.25/kWh at night vs. €0.40 daytime) — Wellis models can schedule heating cycle on night-rate electricity. Combined measures: 20–30% realistic electricity savings.
Home sauna (6 m², 1×/week 2 h): ~1,500–2,000 kWh/year = €600–€900 (DE). Medium outdoor pool (4×8 m, heated): 8,000–15,000 kWh/year = €3,200–€6,000 (DE). Wellis Mars P&P (3-person, year-round): ~2,646 kWh/year = €847–€1,111 (DE). Hot tub sits energetically between sauna and pool. Per usage hour (typically 8–12 h/week for a hot tub vs. 4 h/week for a sauna), the hot tub tends to be cheaper per hour.
Less than expected — about +15% extra between a 3-person and a 6-person Plug & Play. Reason: the larger unit has ~50% more water volume but proportionally little more surface area. Specifically with Scandinavian-Wellis: Mars P&P ~2,646 kWh/year, Callisto P&P ~3,194 kWh/year (+9%), Castor P&P ~3,559 kWh/year (+19%). If you're hesitating between sizes, don't downsize from electricity worry — the size factor is small compared to insulation class and cover maintenance.
One-time heat-up consumption is small compared to the maintenance load: a Wellis Mars P&P (1,000 L, 3 kW heater) takes ~30 kWh from 10 °C to 38 °C = €10–€12 (DE) and needs 18–24 hours. Castor P&P (1,500 L) correspondingly ~45 kWh = €15–€18. Heat-up is NOT a meaningful cost factor — maintaining 38 °C is the main share (95%+ of annual energy).
Wellis publishes two independent values: EU energy class (A–G) per EN 17125, measured at +20 °C ambient — mandatory since 2021 for all EU-sold units. Manufacturer kWh/24 h ranges for summer and DE/AT-winter (-10 °C), measured in Wellis's own factory laboratory in Hungary. Values are verifiable in the official 2025 spec sheet. Recommendation: measure your first month of consumption yourself — a simple energy meter on the 16 A socket (€20–€40) verifies the claims. Wellis owners typically report ±10% deviation from spec-sheet values.
The Wellis Mars Plug & Play (€7200, 3-person) — most compact volume, Scandinavian upgrade available, ~2,646 kWh/year in DE/AT climate. Per ready-to-use person ~882 kWh/person/year. For regular two-person use, this is the most efficient Wellis entry. Larger Wellis models have proportionally similar efficiency — choose Mars/Callisto/Castor by headcount, not by expected electricity consumption.
Considering hydrotherapy applications? See our verified wellness guide: Hot tub for wellness & hydrotherapy — applications, safety, model selection · mechanisms, 9 wellness use cases, EU safety guidance, Wellis model recommendations.
Still deciding? Read the honest 2026 analysis: Is a hot tub worth it? — DE/AT pros, cons, 1×/week threshold, 10-year cost vs spa visits.