COMPONENTS OF THE WATER COMPONENTS OF THE WATER
SUPPLY SYSTEM SUPPLY SYSTEM Module 1 Module 1 DANILO B. PULMA DANILO B. PULMA
Dean, College of Engineering
Dean, College of Engineering
Eastern Visayas State U
Eastern Visayas State Universityniversity
W
The purpose of distribution systemThe purpose of distribution system isis to deliver water to consumer with
to deliver water to consumer with appropriate
appropriate qualityquality,, quantityquantity and and pressure
pressure..
Distribution systemDistribution system is used to describeis used to describe collectively the facilities used to supply collectively the facilities used to supply water from its source to the point of
water from its source to the point of usage.
Water quality should not get
deteriorated in the distribution pipes.
It should be capable of supplying
water at all the intended places with sufficient pressure head.
It should be capable of supplying the requisite amount of water during fire fighting.
Requirements of Good Distribution
System
The layout should be such that no consumer would be without water
supply, during the repair of any section of the system.
All the distribution pipes should be preferably laid one metre away or above the sewer lines.
It should be fairly water-tight as to keep losses due to leakage to the minimum.
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This level provides a protected well or a developed spring with an outlet, but without a distribution system which
normally serves 15 to 20 households within a radius of 250 meters;
LEVELS OF SERVICEEVELS OF SERVICE
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This type of system is composed of a source, a reservoir, a piped distribution network, and communal faucets.
Usually, one faucet serves four to six households within a radius of 25 meters.
LEVELS OF SERVICEEVELS OF SERVICE
Typical Level II System Layout (with Ground Reservoir)
Ground Reservoir
Transmission Main
Distribution Lines
Tap Stand Valve
Typical Level II System Layout
(with Elevated Storage Tank)
Elevated Storage Tank Well Pump Transmission Main Distribution Pipes Tap Stand Valve
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Connections)
This system includes a source, a reservoir, a piped distribution network, and individual household taps. It is generally suited for densely populated urban areas where the population can afford individual connections.
LEVELS OF SERVICEEVELS OF SERVICE
Well source
Water Reservoir
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Spring Box
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Springs, Deep Wells, Surface Water (intake, infiltration gallery/infiltration well)
Chlorinator, sand filter, complete water treatment plant
Raw water tank, clean water tank
Pipeline from source to storage facilities
Distribution mains, control valves, individual connections, fire hydrants, booster pumps
SOURCE FACILITIES
TREATMENT FACILITIES
STORAGE FACILITIES
TRANSMISSION LINE
DISTRIBUTION FACILITIES
Sources
Springs
Sources
Surface Water (River)
Rapid sand filters for surface water sources
Iron & manganese removal for groundwater sources
•
AERATORS
•FILTERS
•
CHLORINATION EQUIPMENT
•pH ADJUSTMENT EQUIPMENT
Facilities Commonly Used for Treatment of Water Wells and Springs
• Aerators (for oxidation of iron, and removal of
dissolved gases, tastes and odors)
• Filters (for removal of oxides, lime residue, etc.) • Chemical mixers (mainly for addition of lime to
adjust acidity)
Aerators
Devices most commonly used for aerating water are:
• Multiple Tray Aerators • Cascade Aerators
• Air Compressor and Diffusor Pipes • Spray Nozzle Aerators
Filters
-Filtration Cycle
Water flows downward through layers of sand and some coarser
medium. The material being filtered out accumulates at, or just below, the surface of the filter media and must occasionally be removed by backwashing then to waste, to eliminate clogging effect of removed pre-treatment.
-Backwash Cycle
Is the most widely used means of disinfecting public water supplies. It aims to kill any
disease-causing micro-organism that might get into the water supply system.
Chlorine Demand –the amount of chlorine that reacts to different compounds of water that combine chemically with chlorine.
Chlorine Residual –The amount of chlorine available for disinfection after chlorine demand is satisfied.
Contact Time –the time required to kill a micro-organism after chlorine first comes in contact with it.
Dosage –refers to the amount of chemical applied to the water. Feed Rate –is the rate at which chlorine solution or gas is
injected into the water.
Basic ways of introducing
Chlorine into the water
Hypochlorination or the
injecting of a chlorine solution, and
Refers to the injection of a solution of a powdered or a liquid chlorine into the water by the use of a HYPOCHLORINATOR.
“pH” is the scientific shorthand for the concentration of hydrogen ions in the water
Value of “pH” in Water < 7.0 - Acidic
7.0 – Neutral > 7.0 - Alkaline
Slightly acidic or slightly alkaline water causes no
problems in water, however, strongly acidic water must be treated in order to prevent corrosion of metallic
pipe, valves, steel tanks and customer plumbing.
Ground tank
Elevated tank
Impound Water
Store Water
Equalize rates of flow
Equalize pressure in the distribution system
Respond to emergencies Purposes:
By material (reinforced concrete or steel)
By location/setting (ground or elevated)
By function (fill & draw or floating)
By material (reinforced concrete or steel)
By location/setting (ground or elevated)
By function (fill & draw or floating)
TYPES OF RESERVOIR TYPES OF RESERVOIR
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1. Capacity - as a rule of thumb, reservoir
capacity = ¼ of daily water demand.
2. In selection of reservoir site, natural elevated
areas should be given first priority. In flat areas where elevated reservoir is to be
constructed, location is preferably built
central to the distribution system or opposite
the source to avoid long and/or large diameter pipes.
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1. Floating-on-the-Line – water is both pumped into the reservoir and distribution system.
Water goes up the reservoir when demand is
low, and water is withdrawn from the tank during peak demand. Requires continuous
pumping at low capacity.
2. Fill-and-Draw System – Water is pumped directly into the reservoir and from the
reservoir, water supply is distributed to the
service area through gravity flow. This
requires high pumping capacity at shorter duration.
Pumps are operated at constant head
Pumps need not be operated continuously
Short-time power outages do not affect water pressure and supply
Pressures in the distribution system may be equalized by strategic location of the tank
Advantages of Ground Reservoir
Lower first cost
Lower maintenance cost
Easy observation of stored-water quality
Greater safety
Avoidance of unsightliness and other
Operating Storage (15 % to 30 % of ADD)
Emergency Storage (2 hrs of Peak Hour Demand)
Fire Storage
Pressure Breaker Intake Box
Isolation Valve
Blow Off Valve
Reservoir
Service Area Air Release Valve
Isolation Valve
Hydraulic Grade Line
Sample Profile along Transmission Pipelines
Sample Profile along Transmission Pipelines
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EL. 54.00
DISTANCE = 4,500 meters
Max OWL = 36.60
Max OWL = 33.50
Assuming a PVC pipe, C = 140, what diameter is required to transmit 30 lps from the spring to the reservoir ?
Pipelines where customers tap
Layouts of Distribution Network
The distribution pipes are generally
laid below the road pavements, and as such their layouts generally follow the layouts of roads.
There are, in general, four different types of pipe networks; any one of
which either singly or in combinations, can be used for a particular place.
They are:
Dead End System
Radial System
Grid Iron System
Dead End System...
It is suitable for old towns and cities having no definite pattern of roads.
Advantages
Relatively cheap.
Determination of discharges and
pressure easier due to less number of valves.
Disadvantages
Due to many dead ends, stagnation of water occurs in pipes.
Radial System...
The area is divided into different zones.
The water is pumped into the
distribution reservoir kept in the middle of each zone.
The supply pipes are laid radially ending towards the periphery.
Advantages:
It gives quick service.
Grid Iron System...
It is suitable for cities with rectangular layout, where the water mains and
Advantages
Water is kept in good circulation due to the absence of dead ends.
In the cases of a breakdown in some section, water is available from some other direction.
Disadvantages
Exact calculation of sizes of pipes is
not possible due to provision of valves on all branches.
Ring System...
The supply main is laid all along the
peripheral roads and sub mains branch out from the mains.
This system also follows the grid iron system with the flow pattern similar in character to that of dead end system.
So, determination of the size of pipes is easy.
Advantages
Water can be supplied to any point from at least two directions.
Hydraulic Considerations:
Friction loss in pipe (Hazen Williams C)
Hydraulic grade line
Pumping Equipment
Most pumps used in waterworks, including both well pumps and
booster, are of the centrifugal turbine or submersible type.
Pump selection
Static water level
Pump size should be determined by : i) Well yield
ii) No. of operating hours
• Base (sustained flow) • Peak hour flow
• Scheduled delivery
iii) “Fill-and-draw” or “Float” system iv) Hydraulic zones
v) Delivery pressures
Pumping water level
- Centrifugal pumps for total dynamic head (TDH) of 6 m or less
- Jet pumps or submersible pump for 6 to 20 m TDH
- Submersible pumps or a vertical line shaft turbine pump for TDH >20 m
Power (Kw) = 9.81 x (1/eff) x Q X TDH Q = discharge (CMS)
TDH = total dynamic head (m) eff = 60% to 80%
Power (HP) = Kw/0.746
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Terminology of Pump Performance
Head and Pressure
Head Loss – Pressure that is lost due to
friction between water and the walls of the pipe or between individual drops of water.
Efficiency – is the total energy supplied to the water by the pump expressed as a percentage of
the total electrical or mechanical energy supplied to the driver.
Pump Efficiency – Usable work produced by the pump.
Motor Efficiency – actual power delivered by the motor
Horse Power (HP) – basic unit of mechanical
energy to lift a given amount through a given distance in a given time.
Total Dynamic Head (TDH) – the total TDH the
pump must deliver includes lift and pipeline head losses.
Lift – the total vertical distance the water is raised. Capacity – is the rate of flow of water being
pumped.
Shut-Off Head – the head pumped against the which there is no discharge.
PALMA PEREZ DEEPWELL MLANG, NORTH COTABATO
Typical Pump to Reservoir Set up Typical Pump to Reservoir Set up