This is not as large an issue in central Missouri as it is farther west, as we have plenty of groundwater and are not really in danger of that changing any time soon. However, it's still a good benchmark for overall resource efficiency.
Our baseline water bill runs between $20-$30/month. That has slowly increased in 2008 (light blue), I assume due to the increased water needs of our animals. The obvious difference between 2007 and 2008 is our irrigation; 2007 was incredibly dry with no meaningful rain from June through October, so it cost us an extra $20/month to irrigate our produce. The big spike in October is not irrigation, but the water use of our on-farm wedding and the effects of lots of people flushing toilets and so on. You can see that it plummets as soon as the guests leave and the irrigation is turned off.