1. Overview of the indoor piping system

The indoor plumbing system will have the following basic types of pipes:

• Water supply and distribution system:  It has the effect of conducting water from the source to the equipment that needs to use water. That water can come from ponds, lakes, wells or water plants.
• Domestic sewage system:  It will bring the used water in daily life to the outside, to the wastewater treatment areas, usually the city drainage systems, storage tanks, etc.
• Ventilation systems: They are connected to the drainage system to supply air to this system, includes pipes in the air, higher than the roof.
• Water-using equipment and machinery:  Indoor appliances that use water include washing machine, bathtub, sink, faucet,... All appliances are ventilated and equipped with traps watertight in waste pipes. It helps prevent odors from the sewage system from escaping.

2. Pipe size regulations

Usually the size of the water pipes in general depends on the equipment used.

Dimensions of water supply pipe:

The minimum diameter of the water supply pipe from the main source is  20 mm.
Branch water pipes, water supply pipes to equipment are at least  13 mm.
Drain pipe size:

Main drain pipes > 102 mm.
Floor drain pipe > 78 mm.
Bathtub, toilet, washing machine … > 38 mm.
Bathroom floor drain > 38 mm.
Base (Toilet ) > 78 mm.
Ventilation tube:

Main tube, straight to the sky > 78 mm.
Other pipes > 38 mm.