Before starting the plumbing work, it is most essential first to prepare the drainage plans. In the same way as detailed drawings are prepared before the starting of the construction of buildings, the detailed drainage plans should also be prepared.
The following points should be kept in mind while preparing the drainage plans:
(i) The drains should be laid in such a way so as to remove the sewage quickly from the building. The quick removal is governed by the fall of the pipes. The drains should be laid at such a slope that self-cleaning velocity is developed in them.
The following slopes are usually sufficient:
(ii) All the drainage system should be properly ventilated on the house side. The ventilation pipe should be carried sufficiently high above the buildings. All the bisection chambers should be provided with fresh air inlets.
(iii) All the drains should be laid in such a way so as to ensure their safety in future.
(iv) The drain should be laid in such a way that in future extension can be done easily if desired.
(v) If the quantity of sewage flowing in a pipe is small, an automatic Hushing tank may be provided on its top for flushing it.
ADVERTISEMENTS:
(vi) All the rain water pipes, sweeping from house and bath water should discharge over gully traps and should be disconnected form the drain.
(vii) All soil pipes should be carried direct to the manholes without gully traps.
Figs. 24.19 and 24.20 show typical drainage layout plans:
