I: BASIC CONCEPTS
The water system in every home consists of 4 basic elements:

1. Water supply and distribution system

This system is a collection of pipes that transport water from the water source to the water-using equipment and from the water heater to the hot-water-using equipment.

The water supply can be the city's tap water, ponds, lakes, bore wells, etc.

2. Wastewater drainage system

Includes drainage pipes and sewer pipes that collect wastewater from equipment, water use areas to water treatment sites: city drainage systems, tanks, tanks ...

3. Ventilation System

Consists of pipes ending in the air, higher than the roof, connected to the drainage system to supply air to the drainage system.

4. Equipment and machinery using water

Washbasin, dishwasher, bathtub, pedestal (toilet), washing machine, dishwasher, water heater, shower...

All equipment needs to be ventilated and equipped with watertight traps in the waste pipe and ensure that the odor gas from the wastewater system is prevented from escaping.

II: LOCATION AND INSTALLATION OF HOME WATER SYSTEM
The water system has regulations and principles that must be followed to ensure good performance and efficiency, and at the same time ensure safety for users.

Therefore, in order to design, install or repair water systems for houses, buildings... need people who know the work and are licensed to operate.

1: Parts of a domestic water system
The main sewer line of the house, building : The horizontal pipe at the lowest position (Usually located under the ground floor) receives all wastewater from the building's drainage pipes and then delivers it to the city's sewer system. >102mm

Visitor door : is a pipe device , which can be used to inspect and clean the pipe, with an airtight lid. >102mm

Drain pipes : all pipes that collect sewage, sanitary water of the building.

Sanitary facilities : devices that use water and discharge dirty water into the drainage system.

Horizontal pipes : horizontal pipes, not inclined more than 45°. >38mm

Vertical outlet : main vertical pipe. > 78mm

Water Trap (Odor Prevention) : thing used to prevent odors from escaping from the sewage system while ensuring good drainage.

Ventilation : pipes connected to the drainage system that ensure air in and out of the drainage system. > 38mm

2: Regulations on pipe size
The minimum pipe size, in general, depends on the equipment used as follows:

a) Water supply pipe

– The diameter of the water supply pipe from the main water supply (water tank on the roof or from the pump) to the hot water tank or to the branch is at least 20 mm.

– The branch water pipes, water supply pipes for equipment use at least 13 mm.

b) Drain pipe

– Main outlet of the building >102mm

– Horizontal exit of floor >78mm

– Bathtub, Urinal, Sink, Washing machine… > 38mm

– Bathroom floor drain > 38mm

– Base (Toilet) >78mm

c) Ventilation tube

– Main tube, straight to the sky > 78mm

– Other pipes > 38mm

3: Regulations on pipe materials and equipment
Pipe making materials include many types. It can be copper, galvanized pipe, abs plastic outlet pipe, pvc ... Should use materials according to regulations or have been tested and evaluated well by practice.

– Sewage pipes: use cast iron pipes, PVC pipes..

– Domestic water pipes: use copper pipes, PPR plastic pipes, PEX plastic pipes…

4: Notes when installing sewage system
-Do not install the "T" connection in the sewage system, except for the exhaust pipe.

– Do not use the “X” connection in the wastewater system.

– Do not use complex connections, limit connections for horizontal pipes in the wastewater system.

– All sanitary waste pipes (from toilets) and rainwater drainage pipes must have access doors to allow the whole system to be cleaned.

– The entrances must be arranged on the upstream side of the water trap and located directly at the water traps of the horizontal main drainage pipes, the garbage discharge pipes.

– At places where there is a change of direction greater than 45o  of the toilet drain pipes, it is necessary to arrange a visit door.

– With the main vertical drain pipes, it is necessary to arrange the opening at the bottom of the pipe.

– Entrances should be easily accessible when needed.

– Each sanitary ware needs to have its own odor-preventing water trap.

– Horizontal sewage pipes with a diameter of less than 78mm should have a slope in the direction of flow of 1/50.

- Manholes, sewage tanks, septic tanks need to be airtight, watertight and must be ventilated. The vent pipe can be 1 size smaller than the largest exhaust pipe.

– Water traps must be ventilated.