CASE HISTORY: INTRODUCTION
Our motivation for collecting rainwater started with a taste of water from a well in the neighborhood where we had land and intended to build a house. The sample came from a well drilled deeply (900 – 1000 feet) into the limestone of the Trinity aquifer. Unlike the Edwards aquifer, water in the Trinity percolates slowly and dissolves relatively large quantities of minerals. Depending somewhat on well location and depth, water from this aquifer can be nearly undrinkable. Our neighbor's taste sample had been treated (softened and demineralized), but we thought it still was awful – so much so that we began to reconsider our building plans.
I'm not sure what started us thinking seriously about the details of harvesting rainwater, but Web searches turned up a number of informative sites and brochures. The most generally useful of these was the Texas Manual on Rainwater Harvesting, now in its Third Edition, developed by the Texas Water Development Board in 2005 and available as a PDF document. This and other sites of interest are listed on the References page.
In our case, we knew the size of our roof catchment area from the architect's drawings (footprint area of the foundation, plus areas contributed by soffits and other overhangs), and given the rainfall data for San Antonio, our task was to estimate the volume of storage that would give us an uninterrupted supply during the extended periods without rainfall we could expect.
OVER TIME ( Updated 27 October 2012)