You can reduce water wasted by taking a navy shower. Essentially this involves running water only as much as absolutely necessary.
Another way of saving water is by not taking daily showers. Twice a week might be sufficient.
Conserving water also reduces household greenhouse gas emissions, in fact it could be one of the easiest and most significant means of reducing our percapita emissions.
We have designed business cards (pdf) with instructions on how to take a navy shower. You can use standard business card paper (I used a sheet with 10 cards - 2" by 3 1/2"). You could use plain card paper and cut it yourself. The PDF is designed to be printed double sided. We recommend laser printing which doesn't smear when wet.