March 28th, 2009
If you’re one of those folks out there who is suffering from a bit of carbon fatigue, then a post in the NY Times’ Green Inc. blog this week could either provide additional motivation for green projects or increased fear of another jargon-laden debate. Green Inc highlighted the growing trend of striving for “water neutrality”, as highlighted at the Fifth World Water Forum in Istanbul last week.
The idea is gaining ground within a group of companies looking to understand and reduce their consumption of water, including Coca Cola, whose chairman has pledged to eventually balance out all of the water used in its products and manufacturing processes through conservation elsewhere (over 80 billion gallons worth!).
This got me to thinking: what would it take to be water-neutral in our own homes, meaning that we don’t import any net water? If we include all of the water that goes into our food and the products we consume, then it gets ugly real fast (see this post on the water content of food, for example). But what about our direct water use - showers, irrigation, toilets, etc?
Now, this would require some significant changes to a home and to local building/health/safety codes, since the only way to go water-neutral is to reuse graywater and harvest/store rainwater. Both of these options now face numerous permitting and legal obstacles around the country (including some pretty counterintuitive ones, like Utah and Colorado bans on capturing ANY rainwater at your home). Assuming we could, though, how much rain would it take to provide a family’s annual water needs?
After some pretty simple calculations, it turns out that the home of a typical family of three could be water-neutral in climates receiving roughly 25″ of rainfall or more per year under the following assumptions:
- Three-person household;
- Rainwater captured, stored and reused;
- Graywater system used;
- Indoor water efficiency measures employed: low-flow showerheads, toilets, faucets and appliances;
- Outdoor water efficiency measures employed: smart irrigation control, rain shutoff, soil moisture sensors, climate-compatible landscaping.
This basically means that home water neutrality is feasible if you live in the Midwest, anywhere along the US Atlantic or Gulf Coasts, in the Northwest and in higher rainfall areas of the West and Mountain West (here’s a set of maps to review for your area). The detailed calculations are shown below. You can use our Environmental Impact Calculator to make similar calculations for your home and region.
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