Dirty mop water should usually go in the toilet, not the bathtub, unless you have a utility sink, service sink, or floor drain made for cleaning water. The goal is simple: send the water into the sanitary sewer system while keeping grit, hair, chemicals, and grime away from drains that clog easily or touch places where people bathe.
I know this sounds like one of those tiny home questions you feel silly asking out loud. I have had the same pause with a full mop bucket in my hands, standing between the bathroom and the tub like I was choosing a life path. Toilet? Bathtub? Sink? Backyard? Suddenly a bucket of gray water feels oddly high stakes.
The short version: the toilet is the better everyday choice in most homes. The bathtub can work in a pinch if you are careful, but it is not my first pick.
Why Dirty
