One of EMI’s clients complained of poor water quality from a large, underground rainwater harvesting system designed and installed by EMI. R&D suspected an unproved design for the “first flush” diverter used in design was underperforming. 

This system is designed to reject a set volume of water at the beginning of a storm, which is calculated beforehand to wash most of the debris from the roof. Water captured after this volume is passed should be of much higher quality. 

R&D conducted tests of various first flush diverters to determine their impact on harvested water quality. The end result was a set of recommendations to improve the quality of harvested water in both the poorly-performing system and future rainwater harvesting systems designed by EMI.