Toilet Water?

Sorry about all the accumulated toilet stuff posted here recently...but it is what it is!   I think about my water usage every time I brush my teeth.

How long do I run the water before it turns hot enough for me to shave?   How much goes down the shower drain?   My roots go back to Bermuda.   In Bermuda, they rely on (and accumulate) rain water for their water requirements/needs.   I remember my grandfather reminding us not to run the water or flush the toilet after every use.   It's amazing what so many of us take for granted.   It really is!