DESIGN LAYOUT OF
DISTRIBUTION SYSTEMS
CE 370
Distribution System Layout
Layout of water distribution system is a function
of:
source of water supply
 topography of distribution area
 variation in water consumption

Source of Water Supply

water is supplied at one point (i.e. treatment plant)
 distribution storage (elevated tank or
ground-level tank plus booster pump) is
required in remote areas to maintain water
pressure

water is supplied at several points (wells)
 storage capacity is reduced and pipe sizes
required are smaller.
Topography
 water
is supplied at high elevation
it
flows by gravity through the water
network.
 water
is supplied at low elevation
must
be pumped up into the water
network (pipes and storage).
Water Consumption
is
a function of residential, commercial
and industrial demands.
planning
and zoning is applied to control
variations in water consumption.
Climate and economical aspects could also
influence the layout of a water distribution
system.
The objective of an engineer designing a water
distribution system is to provide a stable
hydraulic gradient to maintain adequate
pressure throughout the service area and
enough pumping and storage capacities to
meet emergency demands.
The following figure shows simplified water
distribution systems which illustrate the basic
principles of design.
EVALUATION OF
DISTRIBUTION SYSTEMS
Quantity

the water source plus the storage facilities
must be able to provide enough water to meet
both current and future demands (ten years
ahead).

records of average daily, peak daily, peak
hourly rates of consumption of the past ten
years are needed, beside other factors related
to community growth, to project the future
needs.
Intake Capacity

surface water intakes must be large enough to
deliver enough water to meet municipal use
and treatment plant needs during any day of
peak demand.

if storage is not available, water intake
capacity must be large enough to meet fire
demand, maximum hourly flow, and inplant
process needs at the same time.
Pumping Capacity

Low-lift pumps transport water from the source to the treatment plant.

High-lift pumps transport water from the treatment plant to the distribution
system.

Well pumps deliver water to the treatment facilities or directly to the
distribution system.

Booster pumps are needed to increase pressure in the distribution system of
large communities or in areas with widely varying elevations.

Pumping stations must have enough capacity to provide the amount of
water at flow and pressure rates needed to meet both daily and hourly peak
demand plus fire flow.

Pumping stations must be reliable through duplication of units, standby
equipment, and alternate sources of power
Piping Network

Arterial and secondary feeder mains must be designed to supply water
service for 40 or more years after installation.

Actual lifetime of pipes of mains under normal conditions is 50 to 100
years.

Sub-mains must be at least 6 inches in diameter in residential districts and 8
inches in important districts.

Distribution lines are laid out in gridiron pattern

Avoid dead-ends

Adequate number of valves must be installed to allow shutoff in case of
emergency

Valves should be located in a way so that no more than one block will be
out of service in case of emergency.