The average East Bay resident uses 135 gallons of water per day. This woman, who is a low-water expert, uses 30 per day. One observation: almost all of her savings seems to come from not irrigating her garden... so probably if your yard was all gravel, you could save almost this much naturally. The flip side is that almost all the work and expense seems to be from collecting used or rain water to put in her garden.

I am seeing more all-gravel yards in Silicon Valley, perhaps in response to the drought.

I have a greywater system for my garden irrigation and try to keep it down in the house.  We have a well but still, it's important to conserve. 

Grey water systems sound like a good compromise.