Section 5A(2)(i) in The Chennai Metropolitan Area Groundwater (Regulation) Rules, 1988
(i)Percolation/ recharge pits shall be provided around the buildings with minimum size of 1 metre x 1 metre x 1 metre and filled with permeable medium such as broken bricks or pebbles or coarse sand, etc. The number of these pits shall vary based on the extent of the area of water collection. On an average one unit is required for an area of 250 square feet. These structures are suitable for individual houses in general.