Observation Wells Digital Water Level Recorder Telemetry Electromagnetic Flow Meter RWH DWLR CGWB land load cost wells rivers impacts drinking recharge flooding pollution recycling evaporation large tanks groundwater expenditures pumping means allegianceindia storage purpose drainage systems surface reservoirs lessens dependence harvesting methods Ecological benefit Reduced Water Bills subsurface reservoir rain-water harvesting Allegiance Water Management Rainwater harvesting systems Rain Water Harvesting  Advantages