Design Considerations for Drainage and Sanitation System

Objective of design

For the design of drainage and sanitation system of different buildings according to building classification, the objective shall be to safeguard against fouling, deposit of solids and clogging and with adequate cleanouts and inspection chambers so arrange that the may be readily cleaned without the risk of health hazard.

a) The plumbing system shall be designed and adjusted to use the minimum quantity of water consistent with proper performance and cleaning.

b) Plumbing fixtures, devices and appurtenances shall be supplied with required volume of water at pressures adequate to enable these to function properly and without undue noise under normal conditions of use.

Different plumbing systems

For the design and installation for drainage piping, one of the following plumbing systems shall be used:

1) Single stack system,

2) One-pipe system, and

3) Two-pipe system.

1) A single stack system may be used with 100mm diameter stack foe buildings up to 5-storey height. The fixtures in each floor shall be connected to a single stack for increasing the rate of discharge in the downward direction. There shall be at least 200 mm vertical distance between the waste branch and the soil branch connection, while the soil pipe will be connected to stack above the waste pipe. The size of soil branch shall not be less than 100mm. The horizontal branch distance for fixtures from stack and bend(s) at the foot of stack to avoid back pressure as well as the vertical distance between the lowest connection and the invert of drain shall be shown in Fig -1. The recommended depth of water seal trap for different fixtures shall be in accordance with Table-1.