Hate to break it to you, guys...
... But speaking as a former hospital housekeeping manager, I can tell you that hospital mop water is not considered hazardous waste. It routinely gets poured down drains every day, germs and all. There's no reason to think the water from a Rainbow would be treated any differently.
Also, that picture is of a hospital housekeeper, NOT a nurse. Nurses don't clean rooms or vacuum.
Rick C.