Tampa, Florida gets an average of 46 inches of rain a year. Nearly all of that rainwater floods the streets and washes garbage and silt into the Bay. I have been wondering if there can be some good use for those 46 inches. So I set out to do some math to see what that means in gallons. A friend of mine is a fiercely proud Tampan and a math wiz. He lives in a typical Tampa ranch house and here's what he figured out for me.
His typical house has 2100 square feet of roof. Since rainfall is measured officially using the metric system, his roof measures 195 square meters As of last week, Tampa had received approximately 26 inches, or 660 mm of rain in 2008. 660 mm times 195 m² equals 128.8 m³. Since, as everybody knows, a cubic meter of water equals 264 gallons; this means that more than 34,000 gallons of rain water has fallen on my wise friend's roof since January 1, 2008.
Now, since we know the typical Tampa household uses 104 gallons of water a day for a total of 37,960 gallons a year, and we know that approximately 34,000 gallons of water have fallen on my atypical friend's typical roof so far in 2008; I think we can safely say that there's a way out of Florida's water mess. If it's not already obvious, that way out can't be found in the aquifer, in the Hillsborough River or in the new, gazillion-dollar desal plant in Apollo Beach.
Where is the serious discussion of rainwater harvesting? Don't ask because you won't hear it from the Southwest Florida Water Management District or from Tampa Bay Water. Capturing rainwater is too easy I suppose. Here's a diagram of a fully-integrated rainwater harvesting system. Mentioning one of these to a builder in these parts will get you a whole lot strange looks and that's as ridiculous as it is inexcusable. I blame the water authorities for their chronic shortsightedness and inability to plan for a livable future, never mind a sustainable one.
But you needn't wait for Swiftmud or the authority to find this obvious solution, you can get started on your own. Start with a small scale collector. Set a barrel under a downspout and cover it to keep the mosquitoes at bay. Attach a hose to the bottom of the barrel and wash your car with it. Or water your garden. Or give the dog a bath. Or God forbid, water the lawn.
Rainwater harvesting is a smart, efficient use of resources. Get in on it early kids because before too long your water bills will start to look like your electric bills.