How much water do you actually save by making the shower visible, without imposing anything? To find out, we equipped an entire student residence for eight months. The result, measured by sensor: consumption per shower falls by 23%, with no change to flow or pressure. Here is what the pilot shows, and what it means for a landlord or a hotel.
The site: an entire residence, eight months of measurement
The pilot ran at the Résidence Relais d'Italie, operated by Hénéo (RIVP group) in the 13th arrondissement of Paris. Thirty homes were fitted with the Molleaumètre and twenty-eight were retained for analysis, from 13 November 2025 to 30 June 2026. The protocol had two stages: a silent first phase, in which the sensor measures without displaying anything, to set a baseline for each home; then activation of the light ring, with nothing else changed. The full method is set out on the pilot study page.
What we measured
Consumption per shower fell by 23% on average once the signal was switched on, and by 15.5% on the residence main meter across all uses. The gap between the two figures makes sense: the main meter also covers uses the device does not touch, such as sinks and toilets, which dilutes the shower-specific effect. Twenty-four of the twenty-eight homes recorded a fall, with a median reduction of 17% per home and up to 61% among those who started out using the most. No flow was restricted and no pressure reduced: the drop is entirely behavioural, achieved through awareness alone.
| Distribution of showers | Before activation | After activation |
|---|---|---|
| Red zone (> 40 L) | 48% | 33% |
| Showers over 60 L | 23% | 14% |
| Amber zone (20–40 L) | 28% | 41% |
The reading is clear: the heaviest showers become rarer and the bulk of usage settles at reasonable volumes. This is not a handful of virtuous homes pulling up the average, but a shift across the board.
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The saving, in water and in money
Over the period, around 20 m³ of water were saved in six months, with average consumption per student falling from 7 to 5.9 m³ a month. Annualised, and depending on the size of the portfolio, that projects to a saving of €346 to €1,570 a year on water and sewerage, before counting the heating energy avoided, which moves in step since this is hot water. For a landlord, it is a direct reduction in the charges passed on to tenants; for a hotel, a lighter operating line with nothing changed in the guest experience.
And it holds over time
The question that always arises with awareness devices is fatigue: does the effect fade once the novelty wears off? Over the eight months observed, no. After the initial drop, consumption stayed stable, with no drift back towards the starting levels (statistical test not significant, p = 0.87). In other words, the habit sticks. On perception, residents surveyed gave a median satisfaction of 5 out of 5 (mean 4.4/5), and 100% of respondents recommend the device at the six-month review.
What it changes for a landlord or a hotel
A pilot in a student residence offers a useful case for both trades. For a landlord or residence manager, it shows that water charges can be reduced with no building work, nothing imposed on occupants, and tracking home by home. For a hotel operator, the logic is the same on the largest single source of hot water use, the shower, with guest comfort at stake just as strongly. In both cases, measuring per shower makes it possible to compare periods and manage the effect over time.
What remains is to put a figure on what this would mean for you. The savings calculator gives a first estimate in a few minutes.
Across 3,140 showers and eight months in a student residence, the Molleaumètre cut consumption by 23% per shower and by 15.5% on the main meter, through awareness alone. 24 of 28 homes reduced their use, with up to 61% among the heaviest users, an effect that lasts (no habituation) and is well received (median satisfaction 5/5). Estimate the potential across your portfolio or property with the savings calculator.
Source: Molleau x Hénéo pilot, RIVP group, Résidence Relais d'Italie (Paris 13th arrondissement), 13 November 2025 to 30 June 2026, 30 homes equipped (28 analysed), 3,140 showers measured. Consolidated results from the steering committee (2026): 23% less per shower, 15.5% less on the main meter, median 17% less per home, 24 of 28 homes reducing, up to 61% less among the heaviest users, stability over time (p = 0.87), median satisfaction 5/5 (mean 4.4/5). Economic projection based on an average water and sewerage price of €4.69/m³ (SISPEA observatory, 2025 edition, 2023 data).