[wongarsu]

For <10 people there's easy personal accountability and no issues should arise. For 20-50 people I've observed good effects from just having one employee who has the responsibility (and time in their daily schedule) to fill, run and empty the dishwashers. That person can either go around the building collecting everything or police everyone else to put their cups where they belong (in practise almost always a mix of the two).

I don't know how bigger companies handle the issue, but the plan for scaling up seems obvious: have one person responsible for the dishwashers of each floor (or whatever division seems reasonable).