Section 5A(2)(c) in The Chennai Metropolitan Area Groundwater (Regulation) Rules, 1988
(c)Hard-rock areas (weathered). - In hard lock areas also, the rate of percolation of rain wafer will be slow. Therefore, in order to collect and recharge rain water it would be preferable to construct recharge wells of appropriate size. Percolation pits with deep bore holes up to a depth of 50-100 feet shall be provided. In this case, the bore hole is to be constructed with slotted pipe for effective recharge. In general, construction of separate recharge structures shall be provided in the absence of existing infrastructures such as storage tank/ sump, open well or bore well in order to reduce the cost involved.