CHAPTER 8
WATER SUPPLY
PREPARED BY:
NUR AINA BINTI ROHIMI (148538)
Contents
8.0 INTRODUCTION ................................................................................................................................. 1
8.1 GUIDELINES AND SPECIFICATION ..................................................................................................... 2
8.2 PROPOSED WATER SUPPLY SYSTEM ................................................................................................. 2
8.3 WATER DEMAND ESTIMATION ......................................................................................................... 2
8.4 FIRE DEMAND.................................................................................................................................... 3
8.5 POPULATION PROJECTION ................................................................................................................ 5
8.6 WATER RETICULATION NETWORK .................................................................................................... 6
8.6.1 EXTERNAL WATER SUPPLY ......................................................................................................... 6
8.6.1.1 Sizing for Main Pipe ............................................................................................................ 8
8.6.1.2 Peak Flow Analysis .............................................................................................................. 9
8.6.2.1 Water tank storage ........................................................................................................... 13
8.7 INTERNAL WATER PIPING ............................................................................................................... 14
8.8 CONCLUSION ................................................................................................................................... 14
8.9 REFERENCE ...................................................................................................................................... 15
8.10 APPENDIX ...................................................................................................................................... 16
8.9.1 Appendix A1: Water and Fire Reticulation Layout................................................................... 16
8.9.2 Appendix A2 : Internal Piping Layout ....................................................................................... 16
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8.0 INTRODUCTION
Water is distributed to users through a network called reticulation. The distribution
was conveyed to its destination under the pressure generated at the source. Systems for
water reticulation are designed to transport water from its source to its users. Water must be
flawlessly pushed through sufficient energy because it may confront various resistances along
the path. These systems can aid in its mobility, enabling the water to be transported to homes
despite elevation and other comparable obstacles.
Water reticulation systems need to accomplish a number of criteria in addition to
getting water to consumers in order to be effective. One requirement is that they have the
layout, pipe size, and pump capability required to supply the feedlot with water. Additionally,
these systems must be built to deliver adequate water at peak times of year. Water
reticulation systems should also include a storage system to manage fluctuations and fulfil
demand, allow for simple system component maintenance, and have enough features to
safeguard them from all kinds of harm.
There are 3 criteria that need to be considered in designing water reticulation which
is size of pipe, type of material and the location of the component system. The right size is
required for system components that are meant to move water in order for them to function
properly. After all, the overall working pressure of some system components can be
influenced by their diameter and length. The maximum flow rates and final size of the feedlot
must be taken into account by the entire system in order to determine the proper sizing. The
type of material utilised is another aspect to take into account when designing water
reticulation systems. Galvanized steel, black steel, copper, polyvinyl chloride (PVC),
polythene, and other materials can be used to make pumps, tanks, and other system
components. Life expectancy, resistance to corrosion, deposits, punctures, soil movement,
and vehicle weights, ease of bending and installation, and comparative pricing are a few
characteristics to take into account while selecting the material. Since accessibility is
frequently based on location, particularly when it comes to repairs or maintenance, location
is crucial when constructing water reticulation systems. It is important to take into account
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where each component of the system will be placed so that they can withstand the
temperatures of the water being carried and prevent potential damage.
8.1 GUIDELINES AND SPECIFICATION
The planning and design requirement of water supply system in this report are
according to the following guidelines:
1. Uniform Technical Guidelines for Water Reticulation and Plumbing (2018), National
Water Services Commission (SPAN).
2. Guideline for Water Supply (1994), Malaysian Water Association (MWA).
8.2 PROPOSED WATER SUPPLY SYSTEM
The proposed development comprises of 73 units double storey terrace house type A,
87 units double storey terrace type B, 68 units double storey semi-detached house, one surau
and a community hall. The available water pressure is 59.14 to cater for the whole
development area which is located at the outside of the project boundary, and it is direct
tapping to the individual roof tank. The type of pipe used is mild steel cement lined (MSCL)
for external piping and galvanised iron for internal piping with the size used is 100 mm for
domestic pipe supply, 200 mm for firefighting, 32 mm for external pipe to water tank and 25
mm for service pipe. The water distribution network system is a dead-end system.
8.3 WATER DEMAND ESTIMATION
Water demand is the total amount of water needed to sustain a population. Water
demand estimates and take into account historical use rates, population data including
current population and projected population increase, the amount of accessible water, and
return flows.
According to SPAN guidelines, which are based on table B.1: Tabulation of Estimated
Water Demand Rate for Planning of External Water Reticulation System for the Proposed
Development, the entire estimated water demand is determined. The calculated water
demand is displayed below.
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Table 8.1: Calculation of total water demand
8.4 FIRE DEMAND
Fire demand is the quantity of water needed to put out a fire in a given area. This
water must be accessible at a minimum pressure of around 100–150 kN/m2, or 10–15 metres
of head of water as stated in the Malaysian Water Association- Guidelines for water supply
system. The flow rate in the household water pipes is equal to the average flow rates, whereas
the flow rate in the firefighting pipes is equal to the flow rate comparable to the number of
hydrants utilised concurrently.
Our proposed development area is classified as having a class D risk by MWA, with an
average total flow of 1140 L/min and a maximum of one hydrant being operated concurrently.
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Table 8.2: Class off risk for fire demand
Table 8.3: Computation of total fire demand
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8.5 POPULATION PROJECTION
The water demand also can be computed based on the population projection. Attached below is the
calculation using the arithmetic method.
Table 8.4: Population in Kulim district
Table 8.5: Percentage of the population in the country
Table 8.6: Computation for urban population
Figure 8.1: Computation of population projections
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However, this method is not chosen for our project since using the water demand estimation
is much more convenient to compute.
8.6 WATER RETICULATION NETWORK
8.6.1 EXTERNAL WATER SUPPLY
The external water reticulation system in this development project is equipped with a
dead-end network system. The moniker "dead end system" indicates that the pipe system
comprises dead ends. Thus, with the dead-end system, the water does not flow continuously.
The entire pipe network in this system is broken down into various smaller networks. The
main line, sub mains, branch lines, and service connections fall under this category. One main
line is first constructed through the city or region's centre. On both sides of the main line, sub
mains are installed, and the sub mains are then separated into branch lines from which service
connections are provided.
Based on forecasted fire flows and peak flows for the entire development, the water
reticulation system was assessed. On the basis of Hazen William's formula, the analysis was
conducted. The spreadsheet used to calculate the losses for the proposed water distribution
pipeline from the tapping point to the proposed development was used for the computation.
Peak flow analysis tables and fire flow analysis tables both display the output in detail. These
two analyses differ in that they demonstrate their usefulness. In other words, peak flow
analysis illustrates how much water is sufficient to supply each home during peak hours.
When a fire breaks out, a fire flow analysis determines how much water should be supplied
to the hydrant. The hydrants are placed with spacing not more than 180 m, placed at every
junction and branches as stated in the guidelines. Hence, there are a total of 19 hydrants to
accommodate the whole development. Layout for both water and fire reticulation are
attached below.
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Figure 8.2: Location of nodes for water reticulation system
Figure 8.3: Location of fire hydrant
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8.6.1.1 Sizing for Main Pipe
Since the minimum velocity of the pipe is within the range of 0.3 m/s to 2.0 m/s, hence,
we assume the initial velocity to be 1.0 m/s to obtain the minimum pipe size for both water
and fire system. Based on our calculations, the main pipe size for water distribution external
system is 0.15 m while for fire hydrant is 0.6 m.
Figure 8.4: Calculation of main pipe for external water system
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Figure 8.5: Calculation of main pipe for fire hydrant
8.6.1.2 Peak Flow Analysis
The water supply is direct tapping from the existing pipeline system to the water tank
for each house with available pressure of 59. The length of pipe is obtained from node to
node and each node is placed at every junction of the house to reduce head loss.
To obtain the pipe diameter, peak flow, head loss, velocity, hydraulic gradient level (HGL)
and residual pressure, the formula used are as follows:
1. Peak flow, Q = 2.5 x water demand
2. The pipe diameter is assumed to be 100mm to obtain the velocity.
3. Velocity, v = Q/A
4. Hazen William equation is used to compute the head loss.
10.69𝐿𝑄 1.852
ℎ𝑓 = 𝐶 1.852 𝐷 4.87
– Equation 8.1
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Where, hf, head loss
L = length of the pipe from node to node
Q = Peak flow
C = Hazen William coefficient (based on the type of pipe material used)
D = Diameter of the pipe
5. Residual Pressure = available gradient level – head loss
For our project, only two types of pipes will be used which is mild steel pipe from the tapping
point to the distribution node which cross the road and HDPE for the pipe within the
development area.
Sample calculation is shown below:
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Figure 8.6: Sample calculation head loss
The overall of the analysis can be referred in the table below.
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Table 8.7: Computation for water demand
Table 8.8: Computation for fire demand
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8.6.2.1 Water tank storage
Water tank is used to store water before being distributed to the house. It is also
important in storing water for some time if there’s a disruption with the main pipe. In
choosing a tank storage, it is essential in considering the material, size and capacity of the
tank. For safety purposes, the storage tank must be made of corrosion-resistant material and
must have corrosion-resistant coating on the inside. Water in a storage tank intended for
residential use cannot have a flavour, colour, odour, or toxicity added to it. The water tank's
capacity must exceed the building's water needs. Hence, the tank capacity was calculated
with respective of the number of residents in a building to avoid scarcity of water supply.
The water tank was decided to be placed on the roof of the house in order to maximise
gravity force, which will facilitate water flow into the pipes. The installation of pump will be
very costly hence, placing the tank at higher place is much more conventional. The tank
catalogue is from Weida Polystor Sdn. Bhd and the calculation of the tank capacity can be
referred in the table below:
Table 8.9: Computation of tank capacity
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8.7 INTERNAL WATER PIPING
HDPE pipe material with 32 mm diameter was chosen for distributing the water supply
from external pipeline and from water tank. While for service pipe such as in toilet and kitchen
will use 25 mm diameter of HDPE pipe. The layout for the internal piping system can be
referred in the Appendix.
8.8 CONCLUSION
To conclude, the community hall, surau, terrace houses, and semi-detached houses
were all intended to receive water from the water reticulations.
The design was based on the assumption that there would be more than 15 metres of
extra residual pressure head during peak flow conditions, negating the necessity for pumping.
According to the analysis, some of the pipe's velocity, which is less than the minimum
recommended speed of 3.0 m/s, does not meet the standards. As a result, associated
maintenance implications must be presented to the Commission or Certifying Agency for
consideration.
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8.9 REFERENCE
1. Uniform Technical Guidelines for Water Reticulation and Plumbing (2018), National
Water Services Commission (SPAN).
2. Guideline for Water Supply (1994), Malaysian Water Association (MWA).
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8.10 APPENDIX
8.9.1 Appendix A1: Water and Fire Reticulation Layout
8.9.2 Appendix A2 : Internal Piping Layout
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