The designer Rochus Jacob applied an old (an obvious) insight from antiquity to help us start taking baths again.
Baths use a lot of water. But they use less if you have these brilliant "water displacement objects," which sit in your bath, under your knees or whatever, just taking up space. The designer behind these is Rochus Jacob. He explains:
Many people stopped taking a bath in favor for a shower to save water. I always loved taking a bath but felt guilty about the consumption. By adding volumes to your tub, the amount of water used can be drastically reduced without radically changing behavior. 'Water displacement objects' enable people to take a full bath with 50% less water. It is a simply product made out of post consumer water. I unconsciously collected stones at the beach that are just beautifully shaped by nature. 3D scanning them allowed me to manifest their form in a prototype.'
Assuming these things aren't so big as to really get in the way, this is fantastic idea. Archimedes would be proud.