Water filters for bath tubs

This is going to sound weird, but do they make water filters for tubs?? We are on a well and rent. I'm not paying $1,000 for a pump to go on a well and our landlord has been told time and time again and refuses to fix the problem. The water from the kitchen sink and bathroom sinks and showers is fine...its just the one on the tub. It comes out a light brownish color. I know it's just hard water but it's gross looking. I like baths, so I prefer to be able to use it without it looking like mud. Any ideas??