Development of dual water supply using rooftop rainwater harvesting and groundwater systems

Abstract

The aim of this study was to gain a better understanding on dual water supply system consisting of rainwater and groundwater. The pilot study of the designed system was carried out at the Universiti Tun Hussein Onn Malaysia, Batu Pahat, Johor. The first part of the analysis was carried out to assess the rainwater harvesting system efficiency. The monthly results on total quantities of the collected rainfall in storage tank was 48.97 m3 while the actual rainfall calculated was 56.04 m3 with 75% of collection efficiency. The rainfall-storage rating curve was then plotted using 150 rain events data versus the volume of harvested rainwater collected during the study period. The second part of the analysis was to determine the total average pumping rate by conducting a step drawdown test, which gave Q = 39.5 m3/ h. For the daily discharge rate, the well was capable to supply water approximately 1.69 m3. In the current study, the daily water demand calculated was 0.59 m3, which gave the total volume per month approximately from 16.5 to 18.3 m3. Based on the performance of the system, most of the days rainwater could not meet the water demand, thus have to be supported by the groundwater.