Traps are classified into three types based on ir shape. These are P-traps, Q-traps and S-traps. Q-traps are also known as half-S-traps. P-trap resembles shape of letter P, Q-trap resembles shape of letter Q and S-trap resembles shape of letter S.

A trap is used to prevent passage of foul air through it though it permits sewage to flow through it. A trap should be cheap and readily available. It should be self-cleansing and simple in construction. A trap should be of non-absorbent material.

There are various systems of plumbing for drainage of buildings. Only one pipe is used in a single stack system. A separate vent pipe is provided in one pipe system. The traps of basins are not directly connected to vent pipe in partially ventilated single stack system.

Plastic pipes are light in weight. Ordinary tools are used to install plastic pipes. Plastic pipes are non-corrosive and are cheaper than metal pipes.

The flushing cistern in Indian type water closet is normally kept 2 metres above closet. This type of water closet is simple in construction and working and is usually made of porcelain. In this, a great quantity of water is required for flushing.

Partially ventilated single stack system is modified form of single stack system and one pipe system. In this type of system, waste from water closets, basins, etc. is discharged into one common S.W.P. (soil and waste pipe).

The length of bathtubs generally varies from 1.7-1.85 m. The width varies between 0.7-0.75 m and overall height may vary between 0.58-0.6 m.

The depth of a sludge soak pit varies from 2.5-4 m. re is one such soak pit in each house with a life of about 20 years for a family having 6 persons.

The various components of a storage tank are outlet pipe, inlet pipe, overflow pipe, ball valve, scour pipe, etc. A scour pipe is used to clean tank periodically.

Copper water service pipes are of two types. These are light gauge and heavy gauge. Light gauge copper tubes are used for general purpose work where pressure is not more than 0.15 N/mm².