Assessment of Low-Cost Filter Material for Rooftop Rainwater Harvesting Structure

RRWH is the technique through which rainwater is captured from the roof catchments and directed to groundwater. The present study focused on to design low-cost filter material for rooftop rainwater harvesting structure (RRWH) for groundwater recharge. Three technology options (TO) with different filter viz. TO-I (2 meter boulder + 0.5 meter stone + 0.5 meter sand), TO-II (1 meter boulder + 1 meter stone + 0.50 meter sand fill with bottle + 0.5 meter sand), and TO-III (1.5 meter boulder + 1 meter stone + 0.5 meter charcoal + 0.5 meter sand) were evaluated at six locations for comparative performance of these filters during the pre and post monsoon of year 2019 and 2020. Pooled analysis of both the year shows that about 83-97% of roof water passes through the filter which designates a very good and satisfactory performance. Post monsoon study after the installation of RRWH structure revealed that during the year 2019 the water table uplifted from 5.9 to 3.76 meters while during the year 2020, the water table raised from 5.41 to 2.89 meters. Among all the technology options used the filter of TO-II was found to be best in respect of infiltration rate, cost and overall performance. Therefore, the adoption of this technique at mass level with community participation could help in getting the significant results to mitigate the water requirement.