Originally Posted by Wuzzat?
Speakinawhich, how did you size your storage tank?
I used a spreadsheet that helped to define water accumulation and use based on rainfall and water demands. I would attach the file, but it's an Excel file, and this site won't let me attach it.
We figured it out by calculating the rainfall and roof area for harvesting...sort of. We figure we have ~1,000 square feet of surface area draining into the storage matrix. Since we get about .64 gallons of water/inch of rain/square foot of surface, that means we get 640 gallons per inch of rain. We get about 25" of rain annually...which would give us the "capability" to collect ~16,000 gallons.
BUT, to dig a hole large enough to accomodate such a system would have required permits and a soils engineering review to approve. Since this is only a "landscaping" project, we did not need permits for this size system.
I would have loved to double the size of the system to 6-7k gallons, but we didn't want to draw attention to the project.