Drainage Plans of Building

building drainage




It is essential to prepare a detailed plan showing the proposed house drainage system and to get it approved or sanctioned by the competent authority. The following points should be taken care of in the drainage building plan:

1. The site plan of the building should be drawn to a convenient scale and positions of gully traps should be marked on it. The building site plan is normally drawn at a scale of 1: 1000.

2. The longitudinal section of the proposed sewer line should be drawn at a scale of 1: 100. The size of drain pipes should be at least 10 cm but normally 15 cm diameter pipes are adopted.

3. The longitudinal section should show distances, ground levels, invert levels, depth of cutting, size of chambers and manholes, size and gradient of pipes.

4. The position of public or municipal sewer should be clearly shown on the Building site plan. It is advisable to join the house drain at a manhole on the public sewer line.

5. Detailed Building design plans of different floors of buildings show the positions of floor traps, sanitary fittings, etc. They are to be connected by keeping in mind the general principles of house drainage.

6. House drains are laid as per details on the approved drainage plan of the building. 

7. House drains are tested for water tightness and trenches are lastly filled up.

In a multistoried building, Lavatory blocks on different floors are usually arranged one above the other, so that the same soil pipe and vent pipe may serve all of them. A water storage tank is built at the top of the building and clear water is pumped into it from the ground storage reservoir. Ground storage reservoir gets water from the public water supply system. Water from the top storage tank flows under gravity through the pipe to W.Cs and other fitments automatically. The waste discharge from all these sanitary and soil fittings is carried away by a vertical pipe fixed against an outside wall of the building. The discharge flows down through soil pipe into the house-drain which in turn leads it to the municipal street sewers. An inspection chamber is provided at the ground where the soil pipe joins the house-drain. In addition to the soil pipe, a vent pipe or anti siphonage pipe is also provided to preserve the water seals of house fittings. The soil pipe is provided with a wire cage at the top so as to prevent the entrance of birds in them.

How to test Building drains?

Testing of  House drains

After laying, the house drains are tested to ascertain their water tightness. The drains are usually tested in sections between successive chambers and the vertical pipes are tested in groups, each group having one common inspection chamber.

1. Air test for the House drains -In this test, the pipe is kept plugged both at lower and upper ends and the air is forced into the pipe with the help of a pump. All the joints of the drain are coated with the soapy solution. If any joint is leaking it will form bubbles at the joints.

2. Water test for the House drains - In this test, the drain is plugged at the lower inspection chamber, and water is filled in the pipe to cause a pressure equivalent to a head of 1.5 m. There should not be any visible drop in water level within ten minutes.

3. Smoke test for the House drains - This test is carried out to detect the leakage of rain-water-pipes and other vertical waste pipes. In this test, the smoke is forced into the pipe with the help of blowers. Leakage can be sighted by smell or vision of the smoke emitting through the joints.

How to maintain the house drainage system?
Maintenance of House Drainage System

To maintain the efficiency of the house drainage system, it should be regularly inspected and repaired if need be. Maintenance of the house drainage system may be carried out under the following steps:

1. Entry of undesirable elements. The user of the house should be careful in discharging undesirable elements like hairs, sand, grit, vegetable peelings, rage, etc. into the house drainage. These elements will cause blocking of the fitments and affect the efficiency of house drainage.

2. Flushing. All the drains should be flushed with an adequate quantity of water at least twice a day.

3. Inspection. Various sections of the house drainage system should be inspected at regular intervals. If any obstruction or breakage is noticed during inspection, it should be immediately made good.

4. Quality of material. Materials used in house drainage should be of good quality. The internal surface of the sewers or drains and fittings should be smooth.

5. Use of disinfectants. To maintain better hygienic conditions, lavatory blocks, bathrooms, W. C’s, urinals, etc. should be disinfected from time to time.

6. Workmanship. Only licensed or authorized plumbers should be allowed to take up the plumbing work.

 

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