During monsoon the potable water demand for our project will be met by rainwater harvesting. How should the rainwater tank size be calculated in Criterion 21 (GRIHA Version 03)?
Please refer following guidelines for rain water storage and harvesting calculations:
1) For storage - The calculation should be done on average of peak daily rainfall for 3-5 years and proposed storage should have capacity to store minimum 2 days of peak daily rainfall. There should be a facility of segregating first flush from the stored rain water.
2) For recharging into ground - The calculation should be done on average of peak hourly rainfall for 3-5 years and proposed recharge pits should be designed based on percolation rate of the soil.