Hospitality and foodservice
Water for dishwashers and glasswashers
Warewashing depends on water quality: hard water leaves scale on heating elements and spray arms and spots on glasses, and it increases detergent consumption. Softening protects the machines; a reverse osmosis rinse gives spot-free glasses.
How hardness affects warewashing
Commercial dishwashers heat wash and rinse water to high temperatures, which is exactly when hardness precipitates. Scale builds up on heating elements, boilers and rinse nozzles, lengthens cycles and leads to service calls. Hard water also reduces detergent effectiveness, so dosing has to increase.
Spots on glasses have a second cause: the salts that remain dissolved in the rinse water dry on the surface. Softening exchanges calcium for sodium but leaves the total salt content unchanged, so glasses can still be marked. Reverse osmosis on the final rinse reduces dissolved salts and is the usual answer for bars and fine dining.
Choosing the treatment
| Situation | Usual treatment | Point to check |
|---|---|---|
| Several dishwashers and hot water on one supply | Central twin-tank or multiplex softening | Peak flow during service, continuity during regeneration |
| Machine with a built-in softener | Built-in softener set to the local hardness, or central softening | Salt refills and regeneration time between services |
| Glasswasher for bar glassware | Reverse osmosis for the rinse, with softening upstream if required | Production in L/h against the rinse consumption at peak |
| Hard water above the machine manufacturer’s limit | Softening sized on the daily consumption of all machines | Residual hardness recommended by the detergent supplier |
The machine manufacturer’s water specification and the detergent supplier’s settings take precedence.
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Frequently asked questions about water for dishwashers and glasswashers
Why are glasses still spotted with softened water?
Softening replaces calcium and magnesium with sodium, but the total amount of dissolved salts stays the same. Those salts dry on the glass. A reverse osmosis rinse reduces them and reduces the need for hand polishing.
Is the softener built into the dishwasher enough?
It protects that machine if it is set to the local hardness and refilled with salt. When several machines, hot water production and other equipment share the supply, a central softener is usually simpler to operate and keeps treatment consistent.
Does softened water change detergent consumption?
Detergents work more effectively in soft water, so dosing can generally be reduced. The detergent supplier sets the dosing according to the water hardness at the machine.
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