According to Indian Standard code recommendations, flushing storage capacity for factories and workshops is 180 litres per urinal seat and 900 litres per W.C. seat. For cinemas and public assembly halls, it is 360 litres per urinal seat and 900 litres per W.C. seat.

According to Indian Standard recommendations, a water requirement of 135 litres per head per day is assumed for residential buildings. Out of this, 45 litres may be taken for flushing needs while rest 90 litres are taken for domestic purposes.

Inferential meters are used only for high flows. They are also known as velocity meters. For relatively low flows, displacement meters are used.

For drainage of buildings, re are four principal systems of plumbing. These are a single stack system, one-pipe system, two-pipe system and partially ventilated single stack system. The single stack system if effective only in case when traps are filled with water seal of depth not less than 75 mm.

There are three types of water closets. These are Indian-type water closet, European type water closet and Anglo-Indian type water closet. They are used to receive and discharge human excreta directly from person using it.

In two-pipe system for drainage of buildings, separate waste pipe and soil pipe are provided. In this, discharge from water closet is connected to soil pipe while discharge from sinks and baths is connected to waste pipe.

A septic tank is used for treatment of sewage from an isolated group of country houses where a public sewer is not available. The outlet pipe in septic tank is kept about 15 cm lower than inlet pipe.

There are generally two types of meters used in water distribution systems. These are inferential meter and displacement meter. The inferential meter is used to measure flow velocity across a cross-section with a known area.

The size of vent pipe commonly used in house drainage is 50 mm. It is provided for ventilation of system. It is open at top and bottom to facilitate exit of foul gases.

A trap is a bent fitting which always remains full of water, when provided in a drainage system, thus maintaining a water seal. The strength or effectiveness of a water seal is represented by its depth. Effectiveness of trap increases with depth of water seal.