SOMEBODY'S not pulling their weight around here. Soap, I'm looking at you.
Submitter TurboJens explains this fix: The fill valve split in half and the floater does not cut off the water supply. The towel keeps the water inside and the wrench keeps it from overflowing.
Works great as long as you dont turn it on full blast.
Just because you're the landlord doesn't mean you have any idea what you're doing.