Shower hot water costs about €2.11 per room night in a hotel: €0.66 for water and sewerage, and €1.45 for the energy to heat it. Over a year at 80% occupancy, that comes to about €615 per room, and close to €24,600 for a 40-room hotel. This cost often goes unnoticed because it is split between the water bill and the energy bill.
The calculation, step by step
The calculation starts from shower water used in the room. According to the French Directorate General for Enterprise (2024), a hotel uses 240 to 323 litres per person per night across all uses. For showers alone, Molleau uses 150 litres per occupied room per day, as explained in How much water does a hotel room use per night?
| Step | Value | Where the figure comes from |
|---|---|---|
| Shower water per occupied room per day | 150 L | Molleau assumption, based on DGE 2024 |
| Energy to heat 1 litre from 12 to 40 °C | 0.0326 kWh | Physics (heat capacity of water) |
| Water and sewerage price | €4.37/m³ | Molleau calculation assumption (France) |
| Electricity price | €0.298/kWh | Molleau calculation assumption, i.e. €9.67 to heat 1 m³ |
| Water cost per room night | €0.66 | 150 L × €4.37/m³ |
| Energy cost per room night | €1.45 | 150 L × €9.67/m³ |
| Total per room night | €2.11 | of which 69% energy |
| Total per room per year | ≈ €615 | 292 room nights (80% occupancy): €191 water and €424 energy |
Water prices vary by area: see What is the price of water per m³ in France? to compare yours.
What if the water is heated by gas?
The calculation above uses electricity as the reference. If your hot water comes from gas or a heat network, the price per kWh is different, often lower, and the energy share drops accordingly. Conversely, losses in the hot water system (recirculation loop, tanks, poorly insulated pipes) add to the energy actually paid for. The savings calculator lets you enter your own rate.
What makes this cost vary
- Shower length: the main factor, and the only one the hotel does not control. Guests see neither the litres nor the cost.
- Shower head flow: 12 to 15 L/min for a standard head, 6 to 9 L/min for a low-flow head.
- Hotel category: rain showers, bathtubs and leisure stays push consumption up.
- Hot water production: energy type, efficiency, recirculation losses.
And in your hotel?
Thirty minutes to estimate your water and energy savings. No commitment.
How much can you save?
In the pilot run with Hénéo, displaying consumption during the shower brought the average shower down from 45 to 34.7 litres, or 23% less hot water, across 3,140 measured showers. Applied to a hotel room, that is about €141 per room per year: €44 of water and €97 of energy.
For a 40-room hotel, gross savings reach about €5,658 a year. After the Molleau subscription of about €6 per month per shower, the net gain is about €69 per room per year, excluding the set-up fee. Details are on the connected water meter for hotels page.
Shower hot water costs about €2.11 per room night in a hotel, of which €1.45 is energy, or about €615 per room per year at 80% occupancy. Displaying consumption during the shower cuts it by 23%, about €141 saved per room per year. Source: Molleau, molleau.com, based on DGE 2024.
Frequently asked questions
How much does hot water cost per hotel room per night?
About €2.11 per room night for showers: €0.66 for water and sewerage and €1.45 for the energy to heat it, with 150 litres of shower water per occupied room heated from 12 to 40 °C, at €4.37/m³ and €0.298/kWh.
How much does hot water cost per hotel room per year?
About €615 per room per year at 80% occupancy: €191 of water and €424 of energy. For a 40-room hotel, that is close to €24,600 a year.
What share of this cost is energy?
About 69%. Heating one litre of water from 12 to 40 °C takes about 0.0326 kWh, or €9.67 per m³ at €0.298/kWh, more than twice the price of the water itself.
How can a hotel reduce the cost of hot water?
The most direct lever is showing guests their consumption in real time during the shower: across 3,140 measured showers, hot water use fell by 23% on average, about €141 saved per room per year, with no change to flow or comfort.
Sources: French Directorate General for Enterprise, “Water management in the tourism sector” (2024); Molleau x Hénéo pilot, RIVP group, 3,140 showers analysed over eight months, from 45 to 34.7 L per shower on average. Molleau calculation assumptions: 150 L of shower water per occupied room per day, 80% occupancy, heating from 12 to 40 °C, electricity €0.298/kWh (€9.67 per m³ heated), water and sewerage €4.37/m³. Shower head flow rates: market orders of magnitude.