I worked at a restaurant in the kitchen. We had a place on the wall to hang brushes. The GREEN brushes were to be used for food/prep areas only. The white brushes were for cleaning toilets, and other filthy places.

The white brushes were soaked in buckets and rinsed/washed thoroughly in a slop sink, then later, put in the racks that push through the dishwasher conveyor belt that ran through the machine if I recall correctly. It's been more than 20 years