Phoenix Journal · Energy & Cost
Warewashing is usually a kitchen's biggest water use, and that water is heated - so every wasted litre costs three ways at once. Here is where the water leaks away at the pot wash and glass wash, and how to stop it.
The wash-up is the thirstiest corner of most commercial kitchens - and the water bill is only part of the story. Almost all of that water is heated, so every litre wasted at the pot wash and glass wash is really three costs in one: the water itself, the energy that warmed it, and the detergent and rinse aid mixed into it. Warewashing can be the single biggest water use in a kitchen, which makes it the highest-value place to look for savings. The reassuring part is that the machine is not the villain - how it is run usually is.
It is worth clearing up a common misconception first: a commercial dishwasher or glasswasher uses far less water than washing the same load by hand. A modern efficient undercounter machine uses only around two to three litres per rack, where hand-washing the equivalent can run to forty or fifty litres. High-temperature machines, which rinse hot enough to sanitise without chemical additives, are generally more water-efficient than low-temperature ones. So the goal is not to wash less by machine - it is to stop the machine and the area around it from wasting water needlessly. It is worth knowing your machine, too: a warewasher more than about ten years old can use three to four times the water and energy of a current efficient model, and warewashing can account for a large share of a kitchen's total water use, which is exactly why it repays attention before almost anywhere else.
Most of the waste in a wash-up area comes from a handful of habits and settings, nearly all of them free to fix:
Because warewasher rinse water is hot - often heated to 82 degrees for sanitation - every litre you save is also energy you did not have to spend heating it. That is why fixing a running-tap pre-rinse or a half-load habit shows up twice: once on the water bill and again on the gas or electricity that heats the water, which is a large part of reducing gas bills in a commercial kitchen. Add in the detergent and rinse aid dosed into every cycle, and a single wasteful habit is quietly inflating three separate lines on your accounts.
If your water bill looks higher than the size of your operation suggests, the wash-up is the first place to investigate, because it concentrates so much of a kitchen's water use in one area - which is often the answer to why a water bill is higher than it should be.
None of this asks the team to work slower. Scrape rather than pre-rinse under a running tap, fit a trigger spray valve, run only full racks, set the inlet pressure correctly, keep conveyors on auto, and fix leaks and scale promptly. If the machine itself is more than about ten years old, a modern efficient replacement can use a fraction of the water and energy and pay for itself through lower bills. The wash-up is unglamorous, which is exactly why its waste gets overlooked - and exactly why it is one of the easiest places to take real money off the water, energy and chemical bills at once.
Questions
No - far less, per item. A modern efficient undercounter machine uses around two to three litres per rack, while hand-washing the equivalent load can use forty to fifty litres. The machine is the water-efficient choice; the waste comes from how the wash-up is run, such as pre-rinsing under a running tap or cycling half-empty racks, not from the machine itself.
Replacing the running-tap pre-rinse. A pre-rinse held under a running tap can use more water than the wash cycle itself. Scraping plates first and fitting a trigger-operated low-flow pre-rinse spray valve, instead of a running tap, cuts a large amount of water - and, because that water is heated, a matching amount of energy. Running only full racks is the next biggest win.
Because warewasher rinse water is hot, often heated to around 82 degrees to sanitise. Every litre of hot water you avoid using is energy you did not have to spend heating it, plus detergent and rinse aid you did not dose. That is why a single wasteful habit at the wash-up shows up on the water bill, the gas or electricity bill and the chemical bill at the same time.
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