How about some numbers?
Okay it is one thing to talk about water running off a roof and into the sewer system. The question that comes to mind is how much water is running off that roof. Using the figure from the weather service of 7 inches of rain last month I had a friend (former water master for our county) figure out how much water would run off a single story 2000 square foot home. Are you ready for this? The home would have 8,724 gallons of rainwater coming off of the roof.
Some more numbers the average water use for my neighborhood was 5,985 gallons; my household used 4,489. As you can see the water that ran off the roof was more than enough to supply the needs for one month of any family in my subdivision. Lets look at it another way the charge for water is .0878 per 100 gallons so the 8,724 gallons of run off could be a savings of $7.66 in water service charges. As you know there are other charges associated with water use. Supply fee for 8,724 gallons is $12.97, Sewer charge $21.49, not noted here is Federal Storm water Fee and Edwards Aquifer Authority Fee. Using these figures you could save roughly $42.12 by capturing the runoff from your roof. There is one thing I do need to point out and that is water coming off of a roof is not suitable for indoor use without proper treatment. The water can be used to water lawns and gardens. If you have a metal roof it is a little easier to treat the water for indoor use.
You might not be impressed by the monetary savings but think about the amount of water that could be save in a subdivision the size of mine where there is approximately 500 homes. As you can see the amount of water that could be saved is exceptional to say the least and the money adds up too!
Okay still not ready to drop a cistern in your back yard, then how about a few rain barrels? You could catch enough water to take care of the flowers and potted plants in your home. You would also be doing your part to alleviate flooding in your area. You do have a choice, choose green!