Plumbing

Introduction
Plumbing is the system of pipes, drains, fittings,
valves, and fixtures installed for the distribution
of potable water for drinking, heating and
washing in a building, and drainage of
wastewater and storm water from the building.
The water supply system must accomplish two
objectives:
Provision of sufficient amount of water to
serve each fixture.
Provision of no opportunity of backflow of
used water into the water supply pipes.

The drainage system must accomplish two

objectives:
Wastewater must be removed quickly with
minimum chance for stoppage of drains or
leakage.
Entrance of vermins and. sewer gas or foul
smelling air from the drainage system into the
house must be prevented.
Plumbing Fixture: A plumbing fixture is an
exchangeable device which can be connected to
a plumbing system to deliver and drain water.
Fixture Unit
A fixture unit (FU) is a quantity in terms of which
the load producing effects on the plumbing
systems of different kinds of plumbing fixtures
are expressed on some arbitrarily chosen scale.

Flush Tank/Flushing Cistern

A chamber in which water is accumulated and
then discharged rapidly for flushing out water
closets and urinals.
Flush Valve:
A flush valve is a self-closing valve designed to
release a large volume of water when activated.
This mechanism is often used to flush a toilet or
urinal. Water for flushing must all come from the
water supply pipes. This type of fixture requires
more pressure and larger pipes to flush.
 Typical Water Distribution System

Introduction
The fresh water in a water distribution system
comes from a public works. It is first purified and
then sent under pressure through pipes to the
water service line that runs directly into houses,
or other types of buildings at pressures of 55, 60,
or 75 psi and ranging as high as 100 psi.

Disadvantages of High Water Pressure

eventually damages faucets and fittings.
causes water hammer.
excessive loss of water.

Reduction of High Water Pressure

By installing a pressure reducing valve near the
point where the water enters the house, the high
pressure in the pipe line can be brought down to
a reasonable value
Fig : Pressure Reducing Valve
House Service
The house water service is that part of the water
distribution system that runs from the street
water main to the water meter that is usually
inside the house.
 Inside Water Supply
Distribution
Water can be directly fed to the fixtures or
stored in a building reservoir to be distributed to
different fixtures and hot water heater.

Hot water distribution system brings hot water

to the fixtures.

Both hot and cold water lines should run

parallel, spaced at least 6 in. apart

The hot water line should be run to the left side

of each fixture as we face that fixture.
 Use of Valves
1.The water system is equipped with valves that
are placed where they serve the best use.

2.Valves are turned off to repair leaking pipes.

There are different kinds of valves used for a
water system.

-- gate valve is the on off valve which operates

by raising and lowering a wedge or disk into the
stream of flow.
-- globe valve is used for throttling the flow of
water.
-- check valve prevents the backup of water.
-- fixtures have shutoff valves which are used
when repairs are necessary or when
emergencies occur.
 General Considerations for Water
Supply to Building

1.There should be absolutely no risk of

contamination of water supply for domestic
purposes. To ensure this, three things are
necessary

i. There should not be any cross-connection

anywhere between a pipe containing potable
water and pipe containing polluted water.

ii. There should be no back flow from any cistern

or appliance towards the source of supply.

iii. The water supply and the drainage pipes

should not be very close to each other.

2.The pipes and fittings should be thoroughly

watertight in order to protect the building against
possible damage due to leakage. Watertightness
of joints ensures minimum wastage of water and
risk of contamination is also considerably
reduced.

3.The pipework should be amply protected

against any possible damage.

4. Water supply pipes should carry water inside

buildings under adequate pressure in the water
main. However, where available pressures are
insufficient and it becomes necessary to pump
water, underground storage tank, elevated
storage tank(s) and pumping arrangement must
be used
 Layout of Water Supply Pipes
1.The layout of water supply pipes should be
simple and direct as far as possible.

2.The pipes should be laid as straight as

possible. Alignment should also be good
especially where joints are screwed and
socketed.

3. The pipes should be fully protected against

corrosion or frost.

4. The layout should be such as to admit of easy

inspection and repair. Pipes may run through
chases or recesses made in the walls or through
vertical ducts. Burying of pipes in walls or floors
should, as far as possible, be avoided.

5. The layout should be free from the occurrence

of air pockets, sediment traps and noise
transmission.
 Design of Water Supply Piping
Underlying principles are:
1.A study is undertaken to obtain

i. Water flow rates required for give occupancies

and fixtures
ii. Probable maximum demand on fixtures
iii. Friction to flow offered by piping and fittings
iv. Available pressures
v. Static head loss or gain
vi. pressures required at fixtures

2. Knowing the flow rate on a section of piping,

the allowable pressure drop is determined, and
then the required pipe size is
found using nomograph
 Water Supply For Tall Buildings

--- Water in public mains under normal pressures

cannot deliver water to the upper portions of tall
buildings.
--- Water main pressures range from 40 to 80 psi
depending on the elevation of the main in
relation to its source and the fluctuation in
demand.
--- The bottom of a column of water 1 ft high
exerts a pressure of 0.434 psi. Thus, a main
pressure of 40 psi can support a water column
40/0.434 or 92.2 ft high.
--- If water is flowing, some pressure will be lost
from frictional resistance to flow offered by pipe,
fittings, and equipment.
--- Also, about 10 psi should be available at a
fixture.
--- So it is evident that city main pressure will be
used up in order to overcome the friction to flow
and the static head loss and cannot deliver water
to all parts of a building over 5 or 6 floors.

--- The problem is solved by storing water in

underground storage tanks from public mains
and then pumping the water into elevated tanks
--- The number of floors must be limited so that
static pressures in piping at the bottom are not
excessive. About 150 ft from tank to the lowest
fixture is a suitable limit.
--- For tall buildings, it will be necessary to zone
the system to limit pressures.
--- For example, in a building 32 floors high we
might provide an up-feed zone for the bottom 6
floors. The remaining 26 floors could be 2 or 3
down feed zones depending on the maximum
allowable pressure in the distribution system.