Learned this the other day in one of my Hort. classes….very disturbing to a certain extent. My little house is a 748 sq ft bungalow with a 2 car garage about the same size. When I got done with this equation, my total water shed for 1 in. of rain was 932 gallons, times that by my areas total rain fall and we got roughly 26,000 gallons for the whole year. How does your home/workplace fair? Plug in your numbers below and you’ll have a jaw dropper just like I did.
First of all calculate the square feet of all hard surfaces (roof, driveway, patios, decks, etc)
Once you have that plug it in the following equation to find out what your watershed is per 1″ of rainfall.
_______(total sq feet) x 0.083(1″ of rain) = _______ cu. feet x 7.4 gallons/cubic feet
= __________total gallons of runoff/watershed that your home is producing.
If you wish to get the years total, go to your cities website and they should have the average rainfall in the “tourist” section.
Mulitply that by the total above and you get the year’s amount of wasted water.