Or how I applied a squirrelly back-of-the-envelope calculation to Green hysterics
I recently joined Angie's List in order to learn more about local contractors and service providers. As a customer-driven list, it works well. For example, I was able to read comments left by those who used an auto repair shop I was considering. But, then ...
I just received my first copy of the Angie's List Magazine -- The Green Issue. The magazine is filled with pages of Green propaganda, mainly around the forthcoming end to our supply of fresh water (Will we run out of water? is the subtitle). One section focuses on the virtual water cost of common goods, such as a slice of bread requiring 11 gallons of virtual water and a pound of beef requiring 1,917 gallons of virtual water. Another section lists per-capita water consumption throughout the world.
Is this stuff true? Likely. Will it cause me to phone my congressman in order to demand action? Nope. What offended me was the over-the-top fear mongering. To understand more about the numbers, I Googled around and performed a back-of-the-envelope calculation. Instead of focusing on man, I turned to one of nature's own: the squirrel.
The squirrel is a cute, bushy-tailed rodent. A squirrel can be fun to spot in the wild or a total nuisance in your attic. Regardless, the squirrel is a consumer of water. Yet, what is the virtual water consumption per squirrel?
Squirrels eat acorns, approximately 825 per year. And, amazingly, each acorn requires 48 gallons of virtual water. That means a squirrel consumes close to 40,000 gallons of virtual water per year, or 110 gallons per day. Since squirrels do not rely exclusively on acorns, I assumed that a squirrel consumes a total amount of virtual water that is four times the amount for acorns alone, or 440 gallons per day. 
What is the total virtual cost of all products consumed in the US? 1200 gallons per capita per day. Therefore, the tiny rodent consumes approximately one third of the virtual water of the average American. Hmmm.
Is modern society really that hard on the environment?  Maybe we need to rid the country of those thirsty rodents. Wouldn't that make the Greens happy?
 Virtual water includes every drop of water used in the process of creating a product, even evapotranspiration.
 Calculated using the data provided. Yes, and not all squirrels eat acorns.
 It's all back-of-the-envelope, with some pretty big assumptions. It's more fun than science, yet it's all based on info from the web (so, it must be true).
 There is vastly more potable water in Ohio today than existed 150 years ago.