The Algarve’s reservoirs have been below 50% of storage since May 2022. In February 2024 the Government formally recognised a drought alert in the region and approved a framework of response measures. Within that framework, the tourism sector — golf and tourist accommodation included — was explicitly covered, with a requested reduction of 13% against the previous year. In March 2025 the restrictions were eased to 5%, the same for every sector, with 2019 as the reference year.
For a hotelier the reading is simple: water has stopped being merely a cost line and become an allocated quantity, monitored monthly by the Portuguese Environment Agency. And inside a hotel, few operations use as much water per square metre as the laundry.
This article is about where that water goes and what brings it down. The figures come from sector references, not from measurements of ours, and the sources are at the end.
The metric that matters
Measuring laundry consumption in cubic metres per month tells you nothing. Volume climbs in August and falls in February for reasons that have nothing to do with efficiency. The only metric that allows comparison is litres of water per kilo of linen processed — L/kg.
It is a figure almost no hotel operation knows, and it takes two readings to work out: a water meter dedicated to the laundry and the weight of linen processed. If you have no dedicated meter, that is the first investment to make — without it, everything else is talk.
The second thing to know is how the water divides up. In a non-residential laundry, the wash process accounts for 90 to 92% of total consumption. Steam production accounts for 5 to 8% and ancillary uses for 2 to 3%. That has a practical consequence: measures outside the wash process touch at most 10% of consumption. It is inside the machine that it is won or lost.
Where your operation sits
The sector references are strikingly consistent across independent sources — water-efficiency bodies, equipment manufacturers and systems integrators arrive at compatible figures.
| Configuration | Consumption |
|---|---|
| Industrial washer-extractor, no measuresGood performance, no water conservation | 17 – 22 L/kg |
| With rinse water collected and reusedSame machine, final rinse water reused | 12 – 15 L/kg |
| Continuous batch tunnel washerEstablished benchmark for continuous washing | 7.5 – 12 L/kg |
| Tunnel with a recycling systemA further 40 to 80% improvement, depending on the system | 1.5 – 4.5 L/kg |
Before comparing your operation against this table, a warning: the 17 to 22 L/kg describes a machine well run with no conservation measures. An operation running part loads, badly chosen cycles and old equipment typically sits above that. If you measure and find 25 or 30 L/kg, the problem is not the machine — it is the process.
Reusing the rinse water
The final rinse of a cycle comes out practically clean. It is no good for the main wash of the next load, but it does perfectly well for the first bath of that load — the step whose job is to wet the linen and carry off loose soil.
Collecting that water in a tank and feeding it back at the start of the next cycle is the single highest-return measure in a laundry running conventional machines. It is what separates the first and second rows of the table above: from 17–22 to 12–15 L/kg.
In fuller recycling systems, which treat and return most of the effluent, the references point to 70 to 80% reuse of the water, with utility cost reductions of the order of 20 to 30%. These are investments of a different magnitude and make sense above certain volumes.
The measures that cost nothing
Before buying equipment, there are gains that depend on nothing but operational discipline:
- Full loads. A machine at 60% load uses almost the same water as at 100%. Consumption per kilo shoots up, and this is the commonest mistake in hotel laundries, where washing happens as linen arrives rather than by full load.
- Sorting by soil level. Washing lightly soiled bed linen on the same programme as kitchen cloths means applying the most aggressive cycle to the whole load — more baths, more water, more wear on the textile.
- Correct dosing. Too much detergent demands extra rinses to clear the residue. You pay twice: in product and in water.
- Appropriate programmes. Many operations use one or two programmes for everything, nearly always the longest ones, for fear of an inadequate result.
None of these measures requires investment. All of them require somebody to own the indicator — and that is where most operations fall down.
Cold water and ozone
Temperature does not consume water directly, but it is tied to consumption: hot cycles need more rinses to cool and stabilise the textile, and they drag the energy cost of heating along with them.
Ozone systems exploit a useful property: ozone dissolves better in cold water, which allows the wash temperature to come down while keeping the disinfecting action. The documented gains are mostly energy ones — US national laboratories and public efficiency programmes record significant reductions in the volume of heated water per cycle.
A note of honesty: commercial claims about ozone vary enormously, from 27% to 90% savings depending on who is making them. Treat supplier figures with the same scepticism you would apply to any other, and ask for before-and-after measurements in your own operation.
Where the 35% comes from
The figure in the title is not rhetorical, but it is not universal either. It comes out of the arithmetic of the references above:
An operation sitting today at 20 L/kg — the middle of the band for those with no measures in place — and coming down to 13 L/kg through rinse reuse and load discipline cuts exactly 35%. It is not an optimistic scenario: it is the middle of the first two rows of the table.
To give it scale, using the same assumption as our ROI calculator — a 50-room hotel at 65% occupancy processes around 150 kg of linen a day:
| Calculation | Value |
|---|---|
| Linen processed per year150 kg/day × 365 days | 54,750 kg |
| At 20 L/kg | 1,095 m³/year |
| At 13 L/kg | 712 m³/year |
| SavingMultiply by the water and wastewater price your property pays | 383 m³/year |
The 35% is reachable by anyone who does not yet have conservation measures in place. A laundry already running a tunnel washer and a recycling system is probably below 5 L/kg — and will not cut another 35% whatever it does. The more efficient the operation already is, the more each further percentage point costs.
Do it in-house or ask whoever does
If your property runs its own laundry, the path is set out above: measure L/kg, fix loading and sorting, and assess rinse reuse. That is management work, not heavy investment.
If you outsource, the question changes in nature: the water stops being yours and becomes the supplier’s. But it is still worth asking, for two reasons. The first is that the supplier’s consumption feeds into the sustainability indicators that more and more operators and platforms ask for. The second is that a laundry able to answer this question — with a number, not with adjectives — is usually a laundry that measures everything else too.
Three questions: how many litres per kilo you use, do you reuse rinse water, and can you document it. Anyone who cannot answer probably is not measuring.
Where these figures come from
No figure in this article is a measurement by Arelia. They are public sector references and official documents, so that you can check them:
- Consumption split and L/kg bands — Smart Water Advice, benchmarks for commercial laundries.
- Consumption by equipment type — Girbau, water savings in the professional sector.
- Reuse rates in recycling systems — Hotel Business, laundry water recycling in hotels.
- Drought and restrictions in the Algarve — Portuguese Environment Agency, Algarve Drought (RCM 26-A/2024).
- Ozone and cold washing — Pacific Northwest National Laboratory, technical report on ozone laundry systems.