I am a little obsessed with eco-friendly prototypes, convinced as I am that the next indispensable yet environmentally sound product is going to hail from this wealth of, frankly, nuttiness. Such a one is this toilet-mounted washing machine which decants the water from your laundry into the toilet tank to be reused for flushing.
I have no idea if this would actually work in practice, but I recently read an article about how flushing the toilet just four of five times a day uses up the entire water allowance that the UN deems the minimum necessary for survival. Since then, just turning off the tap whilst brushing teeth hasn't seemed enough.
There are other benefits too. People with small flats who might otherwise not have room for a washing machine can shoehorn one in, and anyone with back or knee problems won't find themselves stooping to load the washing machine. Just make sure the lid of the toilet is closed, yeah?
Aside from the slight weirdness of peeing during a cycle (all that thumping and whirling going on behind your head! Although I suppose it gives men something to look at), it does actually seem like a fairly sensible notion. Now, if only we can convince everyone to rip out their existing plumbing...