As per the regulations, under the roof-based RWH, rainwater has to be harvested for use through a filter into a storage tank or for recharge of an open well. In case of a borewell in the building, artificial recharge structure or pits have to be installed irrespective of the nature of sub-soil conditions.
Rain water from rooftop such as tiled/slope roof and flat/RCC may be collected using appropriate size of gutters or pipelines respectively and stored either in collection tank storage structure of appropriate size placed over the ground or underground after proper filtering and disinfection.
Appropriate filter should be used for filtering rain water and should be used for non portable purpose. In case the water is to be used for portable purpose, the owner/occupier shall follow prescribed standards before using. Surplus water available after filling the storage tank/sump may be diverted to the open well or borewell through recharge structure or pits.
Land-based RWH will involve appropriate ground water recharge structure or pits depending on the nature of sub-soil conditions. A provision for 20 litres or more capacity per sq mt of the roof area should be adopted. In case of artificial recharge structure to ground water, a provision at the rate of 10 litres or more capacity per sq mt of land surface should be adopted.
In case the rainwater harvested has be to diverted to the open well, it has to pass through a filter before recharging the well. Appropriate disinfection methods should be practiced before using for artificial recharge of ground water. Contaminated water should not be used as source of water for recharging the open well. In case of storage, rain water harvested should be filtered through proper filter, stored and stabilised in the sedimentation tank before recharging into bore well. Adequate bypass or safety arrangements should be provided in the system where an expert advice may be obtained before recharging the borewell.