Pipes for Drainage

1. Pipes and Gradients

Pipe sizes for house drains and sewers are 100, 150 and 230 mm and in some cases 300 mm. In order to avoid deposition of solid matter, the pipes should be laid as per the recommendation of I.S. Code (IS: 1742–1972), Table 27.4.

Table 27.4 Recommended gradient of sewer discharge pipes

Source: IS: 1742–1972.

2. Positioning of Pipes

The following points shall be kept in view while deciding the positioning of pipes:

1. All soil pipes, waste and ventilating pipes should be conveniently grouped in shafts or ducts with adequate capacity. This provision is needed to allow for inspection and repair work.
2. All the pipes needed for different purposes have to be adequately provided for during the construction stage itself at their appropriate positions.
3. When pipes are not embedded it should run clear of the wall with a minimum clearance of 5 cm.
4. Waste pipes are to be separated from the house drains by using gully traps. This arrangement is essential to prevent entry of foul air or gas, vermin, etc., into the building.
5. The soil, waste and vent pipes should be vertically carried above the top of the building. They are to be covered by copper, plastic or galvanised iron wire domes. The arrangement is needed to prevent nesting of birds or inadvertent falling in of objects inside the pipe.
6. Diameter of pipes used for various purposes are given below (Duggal, 1988)(a) Soil pipe 100 mm(b) Waste pipe – horizontal 32–50 mm(c) Waste type, vertical 75 mm(d) Vent pipe 50 mm(e) Anti-siphonage pipe:Connecting soil pipe 50 mmConnecting waste pipe 40 mm