What are the Different Types of Traps?

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The trap can be defined as fittings at the end of soil pipes or waste pipes to stop foul gasses (odour) coming out of the soil pipe or waste pipe.

It is a part of the drainage (sanitary) system. It is developed or designed such that it retains a small quantity of waste water from the discharge of fitting to which it is attached as a barrier to prevent foul gasses or air entering the building.

Also Read: What is Trap & its Ideal Requirements

Traps are an important component of a plumbing system. They prevent ingress of foul air, insects and vermin from the sewers into the building and resist the spread of disease. Traps are constructed, so that they retain a body of water which acts as a water seal.

Traps should be of the self-cleansing type. They should generate enough velocity from the available flow to have a self-cleansing effect, a smooth finish and a full uniform bore.

Some manufactured fixtures, e.g. water closets, bed pan washers and certain models of urinals have integral traps built within the body of the fixture.

Water closets and in some cases urinals are provided with integral traps. All other fixtures shall be provided with external traps with adequate water seal. Diameter of the trap shall in no case be smaller than the diameter of the outlet of the fixture to which it is connected. Traps shall be of self-cleansing design with uniform bore and shall not be dependent on internal partitions or other movable parts for retention of water seal. Connection of a trap into another trap should not be practiced. Diameter of outlet pipe from a floor trap shall not be less than size of the trap outlet.

Different Types of Traps

Floor Trap or Nahni Trap:

Floor trap or Nahni trap is provided into the floor to collect waste water from bathroom, wash area, washbasin, and kitchen sink etc.

Courtesy - 123rf

Gully Trap:

A gully trap is provided outside the building before connecting it to external sewerage line. It also collects waste water from the kitchen sink, wash basins, baths and wash area.

P, Q and S-Trap:

P, Q, and S traps are classified according to their shape. They essentially consist of U – Tube which retains water acting as seal between the foul gas and atmosphere.


Intercepting Trap:

Intercepting trap is provided into the Interceptor Manhole (Interceptor Chamber). An Interceptor manhole is provided at the intercept of building sewer and Public sewer. Intercepting trap is provided to prevent the foul gases from public sewers entering into the building sewer by providing water seal.

Courtesy - triotech

Bottle Trap:

A bottle trap is provided to receive waste from washbasin, kitchen sinks and other appliances where the appliances do not have built-in it trap.

Courtesy - 123rf

Grease Trap:

Grease trap is installed in the waste pipe from one or more fixtures for the purpose of separating grease from the liquid and retaining the grease.

Courtesy - 123rf

Traps installed in the areas not in normal use may lose their water seal due to evaporation. Provision must be made to renew the seal by adding water periodically and this can be done by connecting a waste appliance to the trap (e.g. a wash basin, etc). Replenishment is also achieved by installing a sophisticated water supply valve with a back-flow prevention device that is connected to the trap. Care has to be taken to prevent installation of traps that are exposed to freezing conditions.

Also Read: What is Gully Trap?
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