Section 6 in The Chennai Metropolitan Water Supply and Sewerage Board's Sewerage Regulations, 1988
6. Method of laying house sewer pipes and fitting etc.
(a)On receipt of approval, all internal sewer, soil and water pipes and fitting up to the terminal chamber of the premises shall be laid by a plumber licensed by the Board, under the supervision of authorised authority of the Board. The authorised authority after having satisfied himself that the works had been carried out in conformity with the regulations and as per approval shall issue a certificate free of charge that the pipes and fitting have been laid and executed in a satisfactory manner in conformity with the sewerage regulations.(b)All pipes and fitting shall be laid at the applicant's cost and no applicant shall be entitled to allow his sewer to empty into a sewer of the Board unless and until the certificate mentioned in clause (a) above is furnished.(c)(i)The sewer shall be of adequate size. - In no case shall it have an internal diameter of less then 100 mm nor more than such size as may be necessary for the flow or as may be approved.(ii)The standard gradient for the sewer shall normally be 1 in 40 for 100 mm diameter and 1 in 80 for 150 mm diameter sewer.(iii)Missing.(iv)Every change of direction should be formed by properly curved pipes or channels with means by building a manhole at the change point. Manholes shall have side walls with brick in Cement Mortar 1:3 to a minimum of 23 cm thickness and foundation with concrete 1:3:6 for a minimum thickness of 15 cm and with an inter opening of 45 cm square(v)Stoneware pipes with socket spigot joints shall be joined using cement mortar with 1 part cement and two parts of sand measured by volume over initial packing with spun yam soaked in tar or cement and caulked.(vi)Every pipe shall be securely bedded on firm ground and filled round with selected material free from large stones, watered and well rammed into place. Where any sewer traverses softer yielding ground or where subsoil water is met with such sewer shall in addition, be bedded in or completely encased with concrete to a minimum thickness of 130 mm.(vii)Every sewer line be tested to a hydrostatic pressure heed of 1.5 m of water over the highest point of the sewer. The sewer shall show no signs of leaking or oozing after the pressure has been maintained continuously for 1 hour and no pipe shall be covered up until it passed this test to the satisfaction of the authority.(viii)Bends and junctions shall be grouped together and wherever possible provided with means of access by building manholes around them.(ix)All fittings shall be placed on a bed of concrete for a minimum thickness of 100mm.(x)The terminal manhole of the sewer within the premises shall have benching and channelling so done as to connect to the Board's sewer obliquely in the direction of flow of the Board's sewer and avoid any right angled junctions either vertical or horizontal.(xi)No sewer shall be laid under a building, but wherever inevitable, shall be laid in a straight line for whole stretch with cast iron pipes properly joined with lead. If the authorised authority permits, stoneware pipes encased all round with cement concrete to a minimum of 150 mm may be used.(xii)Wherever a sewer is laid across a water main of line, it shall be provided with encasing by concrete as in sub-clause (xi) above.(d)Exclusion of rain water and salt: Every inlet to the sewer conveying waste water sullage or sewage shall be so located at such a level as to prevent storm water entering the sewer. No inlet or connection in any form to the sewer, for purpose of draining surface or subsoil water shall be permitted.(e)Method of laying vertical pipes (soil-pipe, waste-pipe, vent-pipe etc).(i)All soil-pipes connecting closets, urinals, shall be connected directly to the manhole of the sewer and shall be not less than 100mm diameter.(ii)All waste-pipes shall be led to the gullies or traps immediately below them, and terminated at or within 150mm so as to have free circulation of ambient air and shall not be less than 75 mm diameter.(iii)All Vertical-pipes shall be free from bends (to the extent possible) properly secured to the wall by suitable clamps.(iv)All bends and junctions in vertical pipes shall have hand holes conveniently located so as to enable cleaning of any obstructions without difficulty.(v)All vent-pipes connected to manhole and water closets shall be taken sufficiently above roof level so as to create the least nuisance or inconvenience to the inhabitancy of the neighbourhood from foul air.(vi)Jointing shall be with lead, cement, or cement mortar depending on whether the pipe is Cast Iron, Wrought Iron or Asbestos Cement and shall conform to the specifications quoted elsewhere.All other internal fixtures with their connection shall be as per the standard practice and subject to approval of the authority.
