Eureka!
I was pouring a glass of water from my BRITA jug. I also needed a piss. There followed my eureka moment: The BRITA Toilet.
Update: Stage 1 of The BRITA Toilet R&D process has gone disgustingly.
Update 2: Theoretically just connect toilet to taps with a BRITA filter in between. May also require a SHITA filter, thinking about it.
