an alternative option....I have an old frame house with single bath.. during hurricane season, without power, it gets pretty hot, and a shower is a welcomed opportunity to cool off...I use a 33gal trash can placed in the rear of my tub/shower for non potable toilet flushing if need be (it has been quite a few years since we've lost city water, but it has happened when sanitary sewer lift station have lost power and flooded, contaminating the water supply)... by not using something like the Water BOB, I have a place for water storage, and still have access to my shower drain...