Rainfall Harvesting Math
...ain a fair amount of water after a rain, but they will still work fine for rainwater collection. Data on both yearly and monthly average rainfall can be found on the National Oceanographic and Atmospheric Administration website. For our house here in Los Angeles, we have a collection area of 992 square feet, a pitched asphalt shingle roof and an average of 15.06 inches of rain a year. So the average amount of rain we could collect in a year would...