It is done by following two methods-

(i) Conservancy/Dry system:

Different types of refuses are collected sepa­rately and then each type is carried and suitably disposed off. Garbage- dry refuse, night soil lavatories and sewage, storm water & sullage channels are made for discharging.

(ii) Water carried sewage system:


Construction of latrine water closets (W.C.)

Construction of plumbing system for collection and movement of the sewage till it is carried and discharged in to the nearest municipal sewer or septic tank.

Wash basins, bath tubs, kitchen sinks, urinals, latrines, flushing cisterns do contribute to the sewage. A system of pipes should be laid and connected with sanitary fittings in such a way that the sewage automatically flows by gravity. Following are used-

(a) Back vent:


Any vent which allows air to enter in a waste pipe so that water will not be drawn out of traps by a siphoning action.


A pipe that allows flow of air to or from the drainage pipes or any pipe providing the circulation of air within the drainage system.

Air Vents:


These are attachments mounted on the vent pipes fitted with the inspection pits for providing supply of fresh air to the sewerage system. These are provided with mechanism of mica valve which allows entry of fresh air, but do not allow foul air to come out.

(b) Waste pipe:

Applied to drain which received the discharge from fixtures other than water closets, urinals & fixtures receiving human excretes.

(c) Trap:


A downward looped section of pipe in the lower part of which remains a quantity of water.

Bench vent pipe which connects from a branch in the drainage system of the vent stack.

(d) Vent stack:

Vertical mains in the vent system



Vertical main in the drainage system

(e) Continuous waste & Vent:

Consists of a vent pipe and a waste pipe which are in a straight line.


Dry vent:

A vent which carries water or water borne waste at no time.

Dual vent:

Connects to the point at which two fixture drains come together.

Waste stack:

A vertical waste pipe

Building drain:

The pipe which receives the discharge from stacks and other drain pipes and leads outside the building to the building sewer.

Building Sewer:

The pipe which receives the discharge from the building drain and conveys the sewage to a public sewer or any other place at which sewage is treated.

Drain pipe:

It carries away water, other liquids and water borne waste.

Fixture drain:

The portion of a drain line between the trap of a fixture and the point at which this drain joins any other drain pipe.

Horizontal branch:

A drain pipe which extends from the soil stack, waste, stack of building drain and receives the drainage from one or more fixtures.


Any principal pipe to which are connected drain and waste pipe either directly or through branches.

Relief vent:

Connected between a branch from the vent stack and soil stack or a waste stack, primarily for the purpose of allowing air to circulate between two stacks to which connected.

Soil pipe or stake:

Receives the discharge from any plumbing fixture in the building. If it is vertical, it is called a soil stack. It extends through the roof and its lower end connects to the building drain.

Wet went:

Any portion of a waste pipe which acts as a vent for other fixtures on the same line.

Antisyphonage Pipe:

Antisyphonage is the device to preserve the water seal in the traps by provid­ing ventilation. When more than one water closet discharge in the same soil pipe, the portion of the trap to the branch soil pipe should be ventilated from a point not less than 75 mm or more from their highest part by Lead or cast iron.

Pipe of not less than 50 mm diameter are carried up to preferably 5 cm. antispyhonage instead of connecting to the soil pipe.

When this antisyphonage or ventilation arrangements is not provided, then, in a multistoreyed building, the sudden flush of water in the upper storey results in to the soil pipe of the lower COWL – The top of vent pipe is provided with cowls ball Cock – Opens due to ball position.

Sucking of air from the short branch of the pipe connecting the water closet storey. This sucking causes partial vacuum in the downstream side of the water seal of the lower water closet and the water of the seal syphoned into the soil pipe.

Provision of the antisyphonage pipe causes break of syphonic action and preserves the water seal of the water closet at the lower level.

Principles of Water Carried Sewage Systems: These are:

(i) Sewer pipes should be preferably laid by the side of building.

(ii) Drain should be laid straight between main holes inspection chamber. All sharp bends and junctions should be avoided.

(iii) The plumbing system should contain enough number of traps at suitable points.

(iv) Building sewer should be disconnected from the public sewer by the provision of intercepting trap.

(v) Joints should be water tight.