Feasibility Study of Rainwater harvesting As a Saving Option of Ground water

Abstract

For the work purpose, Mirpur DOHS has been selected as case study area. We collected rainfall data and community water demand data for the analysis. Our main focus is to save groundwater and use rainwater from harvesting. After analysis we have got Annual average rainfall is 6.47 m. Annual rainfall volume is 1310626 m³. Total Annual water demand in the area from 25 liter/sec extraction in a day is 2365200 m³. Total annual water saving can be made up to 55%. Monthly % savings have been also shown in the table in the data analysis section. Annual Water cost from demand at a rate of 11.02 Tk per 1000 L water is 26064504 BDT. Net Cost savings from rainfall harvesting is 11621402 BDT which is 44% of the total water demand cost. Net cost savings will not be achieved fully as there will be some treatment cost for rainwater. Maximum rainfall over the past 11years in a single day is 448 mm. So, maximum rainfall volume in a single day from per roof is 70 m³. Underground reservoir capacity in a building at Mirpur DOHS is 32' x 14' x 11' that means 139 m³ in volume. So, harvesting rainwater can be easily accommodated in the underground reservoir using a primary treatment option like filtration.