Guidelines for Fixing Rain Water Pipes

Rainy water consists of storm water (rainy water), surface water, street wash and washing water excluding sewage and industrial waste.

It is harmful to foundation and health of the occupants of the house if it’s not expelled properly. A good quality rain water pipe and its’ proper fixation make your home neat, clean, safe of mud and rain water. Wrongly fitted pipes can cause harm to the contents of the building. For smooth flow of rain water and better understanding of pipe fixation, here are given some nice tips.

Pipe for Drainage of Rainy Water

Asbestos cement pipes are widely used for drainage of rainy water. The following are advantages of asbestos cement pipes.

Light weight
Tight joints
Easy to handle
Quick in laying and back filling
Easy in cutting, drilling, threading and fitting
Non-corrosive for most natural soil conditions
Free from electrolytic corrosion (rust)

A structure of Rain Water Drainage

(This picture is contributed by"S.Krishnan")

Recommended Size of Rain Water Pipe

Number and size of pipes for rainy water is determined by the area of roof to be drained and on the basis of average rate of rainfall in the area. The pipes for rainy water should normally be sized on the basis of roof area as given below.

S.No.	Diameter of Pipe (Mm)	Average 50	Rain 75	Fall 100	In 125	Mm/Hour 150	200
1.	50	13.4	8.9	6.6	5.3	4.4	3.3
2.	65	24.1	16.0	12.0	9.6	8.0	6.0
3.	75	40.8	27.0	20.4	16.3	13.6	10.2
4.	100	85.4	57.0	42.7	34.2	28.5	21.3
5.	125	--	--	80.5	64.3	53.5	40.0
6.	150	--	--	--	--	83.6	62.7

Required Appliances for Rainy Water

Rainwater collected within building is carried down through gutters and pipes. Building sewer carries rainy water also in a partial separate system where a portion of rainy water is mixed with sewage.

Materials for Filling in Pipes

The following common materials are required for filling in the pipes.

S. No.	Material	Weight Kg/M3
1.	Dry Sand	1600
2.	Ordinary Damp Sand	1840
3.	Wet Sand	1920
4.	Saturated Clay	2080

Guidelines for Execution of Pipe Works for Rain Water

The pipes for rainy water should be fixed outside external walls of building.
Any pipe for rainy water should discharge rain water directly into surface drain outside the house or from compound drain to surface drain out side the house.
An inlet of bell mouth at roof surface should be provided.
The spacing of rain water pipes in the wall should depend on position of windows and ventilators openings, but distance between rain water pipes should not be more than 6 meters.

Plastic Rain Water Pipe

(This picture is contributed by"S.Krishnan")