I use a similiar rule of thumb with regard to flushing the toilet.  At night, I don't flush the toilet at all.  Once I go to bed, I let whatever happens in the night stay in the toilet until morning.  Not only does it save on water, but no one gets woken up.

Sometimes I will do that during the day if I know we won't be getting any company. 

I have really become quite conscientious about my water use especially since I am in San Diego and we had less than 4 inches of rain this year (I laughed when a recent Post-Doc from India asked what our rainy season is like. What rainy season?) What I find helps both my water bill and my conscience is to turn the water off whenever I am not physically using it, say when rinsing dishes to put in the dish washer (that I only run every third day), or brushing my teeth (I don't let it run to warm up anymore, might hurt my teeth a bit but I feel better in the long run), and not turning it on full blast when I do use it. I water my outdoor plants with a bucket instead of the hose, that helps to. Glad to hear that you are doing so much, keep it up!

I started doing this to save on my water-heating bill, but "camp showers" are another way to conserve. Basically, you only turn the water on in the shower when you initially get in (to get wet). Then you lather up and get your shampoo in, then when you're ready to rinse, turn it on again. Same if you're conditioning. That way, you're only using the water when you need it. It saves water as well as electricity (or gas, depending on your system). I guess in the winter it could get a bit chilly, but we'll see come november! hehe. 

My dad used to make us do that at our summer home in the mountains.  It was weird at first, but you caught on.  I can't imagine it in the winter though.  You would have to close the door and let the steam arm you up.

I have a cure for your septic tank.  There are all natural pellets you can buy that eats away at the waste in the tank, but what my family does that seems to save on it is to NEVER FLUSH TOILET PAPER!  They say it breaks down, but in all honestly, it takes a while to break down and in the meantime-just sits there.

 

As for the water, out town was forced to buy bottled water for a while.  So, after spending tons of money on it, I noticed that some companies have bottled tap water and it's a lot cheaper.  We used that for a while.