Dish and glass washing

Find out about the conditions of discharge for dishwater and glass washer waste to the wastewater system.

Hot wastewater or that containing excess soap or detergent, if discharged to a standard size pre-treatment fixture, will liquefy or emulsify grease already present in the fixture allowing the grease to be discharged to the wastewater system.

As the grease-laden effluent flows down the wastewater system it will cool causing the grease to solidify and be deposited in the system, leading to grease fouling and blockages.

Some washing soaps and detergents break down over time releasing the grease from the emulsion, which is also deposited in the wastewater system.

Cool liquid also inhibits the emulsifying action of some washing soaps and detergents, however, control over excessive use is still required.


Water from dishwashers and glass washers must be discharged to the wastewater system downstream of any site pre-treatment fixture.

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