1. Plumbing system fundamental and design course
Lecture (3) : Design of cold & potable water systems
Eng: Ali Widaa Ali

2. Design of cold & potable water systems
Estimation of minimum number of plumbing fixtures for facilities( residential, hotels, schools etc. )
Fixture unites ( water supply & drainage fixture units)
Piping materials for water distribution
Sizing plumbing water systems

3. Estimation of minimum number of plumbing fixtures

8. Water supply Fixture Units
A quantity in terms of which the load – producing effects on the plumbing system of different kinds of plumbing fixtures are expressed on some arbitrarily chosen scale.

11. Water supply demand

14. Design of hot and cold water system
Water storage in the building:
Domestic & potable
irrigation
fire fighting
water storage in the building:
underground tanks
Roof tanks

15. Storage of water:
Water is stored in buildings due to the irregular supply of city water. Normally water is stored in basement with pump transferring water to roof tanks. Roof tanks could one single tank for the whole building or separate tanks for each flat.
Water tanks are provided normally with float valve, drain valve, discharge valve, overflow and vent pipe. Roof tanks should be elevated enough above roof level to have enough pressure for the upper apartment, otherwise booster pump is needed.

16. Sizing plumbing water systems:
Common water supply systems
Up Feed (direct) water supply system.
Down Feed (indirect) water supply system.

17. Steps for sizing Water supply systems:
Daily Water Requirement:
Daily water requirement &Tanks capacities is based in the fixture supply units .

18. Water storage tank

19. Water storage tank

20. Water storage tanks Plastic and fiberglass water tank

21. GRP Water tank

22. Concrete water tank

23. Sizing and selection of water storage tank
Water storage size =
Water supply demand * Water Storing Period

24. Piping materials for water distribution
Galvanized steel pipe
Copper Alloy pipe
Plastic pipe
- CPVC
- PPR
- HDPE
- PEX

25. Steps for sizing water supply systems
The water distribution system shall be designed, and pipe sizes shall be selected such that under conditions of peak demand, the capacities at the fixture supply pipe outlets shall not be less than shown in Table

27. Size of fixture supply
The minimum size of a fixture supply pipe shall be as shown in table The fixture supply pipe shall not terminate more than 30 inches ( 762 mm) from the point of connection to the fixture . A reduced-size flexible water connector installed between the supply pipe and the fixture shall be of an approved type. The supply pipe shall extend to the floor or wall adjacent to fixture

29. Selection of pipe size
Before attempting to size any water supply system, it is necessary to gather preliminary information which includes available pressure, piping material, select design velocity, elevation differences and developed length to most remote fixture.
Water pipe sizing procedures are based on a system of pressure requirements and losses, the sum of which must not exceed the minimum pressure available at the supply source. These pressure are as follows:

30. Pressures Pressure required at fixture to produce required flow.
Static pressure loss or gain ( due to head)
Loss through water meter.
Loss through taps in water main.
Losses through special devices such as filters and regulators
Loss through valves and fittings.
Loss due to pipe friction

33. Selection of pipe size
The objective in designing the water supply system is to ensure an adequate water supply and pressure to all fixtures and equipment.
Divide the system into sections breaking at major changes in elevation or where branches lead to fixture groups.
Draw draft schematic of the piping from the main line to the all fixtures.
Determine from tables and charts:

34. Selection of Pipe Size
1.The minimum pressure needed in each line. 2. The minimum flow rate needed in each line ( hunter curve or the table) 3. The length of the section. 4. Equivalent length fittings and valves 5. Total equivalent length (3+5) 6. Friction loss per unit of length of trail size of pipe 7. Friction loss in equivalent length (6*5) 8. Excess pressure over friction losses