The Solution
This project out in Hays County, TX, involved two separate buildings. The design of these tanks consisted of several challenges: main cisterns were 60 feet higher than house gutters, multiple heritage trees close to house, main cisterns with different heights, and different elevations for cistern locations. Because of the trees and organic matter that could be present in the water, the client chose four additional options to filter the rainwater before it entered the main tanks for later use: premium stainless steel gutter covers, two roof washer boxes, an auto-flush computer, and a commercial sand filter. In order to overcome the 60-foot elevation difference, a “stage” type system was designed: one 1,200-gallon “stage or surge” tank with a 3 HP transfer pump and sand filter. If any organic material such as twigs, pollen or leaves makes it past the gutter covers and automatic first flush, they are trapped by the roof washer boxes keeping the stage tank very clean. The sand filter polishes the water before it enters the main cisterns and decreases filtration unit maintenance. The automatic flush controller is configured so that it regulates the transfer pump and filling the main cisterns evenly that have different heights. Because of the uneven terrain and aesthetics, more excavation was needed along with a retaining wall. A concrete foundation was used for the metal tank to minimize the tank’s footprint and to also integrate a concrete footer for a small retaining wall.
