Size a rooftop recharge pit for a 120 m² roof in a 1,000 mm/yr rainfall area, on soil that infiltrates 25 mm/hr.

1. 1Under Design Code / Country, select India (CGWB / IS 15797).
2. 2In Catchment, enter Roof area 120 m², Annual rainfall 1000 mm and Runoff coefficient 0.85.
3. 3In Storm & Soil, enter Peak rain intensity 50 mm/hr, Soil infiltration rate 25 mm/hr and Storage buffer 30 min.
4. 4In Pit Geometry, enter Pit depth 2 m and Filter media porosity 0.4. Leave Count base infiltration (CGWB manual) unticked.
5. 5Select Size Pit.