Section 82(1)(a) in Assam Notified Urban Areas (Other than Guwahati) Building Rules, 2014
(a)for buildings of height upto Ground + 1 Floors, percolation pits of 30 cm diameter and 3m depth may be made and filled with broken bricks (or pebbles) for 2.85 m and the top covered with perforated Reinforced Concrete Cement (R.C.C.) slab. These percolation pits may be made at intervals of 3m center to center along the plinth boundary. The rain water collected in the open terrace may be collected through a 150 mm PVC (Poly Vinyl Chloride) Pipe laid on the ground and may be allowed to fall in the percolation pits or into a open well through a seepage filter of 60 cm x 60 cm (filter media broken bricks) provided before the open well which shall improve the ground water level. A dwarf wall of 7.5 cm height is built across the entry and exit gates to retain water and allow it to percolate within.