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1. Components of Water Supply System

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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

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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.

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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

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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

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Typical Level II System Layout (with Ground Reservoir)

Ground Reservoir

Transmission Main

Distribution Lines

Tap Stand Valve

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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

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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

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Sources

Springs

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Sources

Surface Water (River)

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Rapid sand filters for surface water sources

Iron & manganese removal for groundwater sources

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AERATORS

FILTERS

CHLORINATION EQUIPMENT

pH ADJUSTMENT EQUIPMENT

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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)

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Aerators

Devices most commonly used for aerating water are:

• Multiple Tray Aerators • Cascade Aerators

• Air Compressor and Diffusor Pipes • Spray Nozzle Aerators

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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

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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.

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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.

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Basic ways of introducing

Chlorine into the water

Hypochlorination or the

injecting of a chlorine solution, and

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Refers to the injection of a solution of a powdered or a liquid chlorine into the water by the use of a HYPOCHLORINATOR.

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“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.

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Ground tank

Elevated tank

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 Impound Water

 Store Water

 Equalize rates of flow

 Equalize pressure in the distribution system

 Respond to emergencies Purposes:

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 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.

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 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

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Advantages of Ground Reservoir

 Lower first cost

 Lower maintenance cost

 Easy observation of stored-water quality

 Greater safety

 Avoidance of unsightliness and other

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 Operating Storage (15 % to 30 % of ADD)

 Emergency Storage (2 hrs of Peak Hour Demand)

 Fire Storage

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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 ?

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Pipelines where customers tap

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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.

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They are:

Dead End System

Radial System

Grid Iron System

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Dead End System...

It is suitable for old towns and cities having no definite pattern of roads.

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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.

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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.

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Advantages:

It gives quick service.

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Grid Iron System...

It is suitable for cities with rectangular layout, where the water mains and

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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.

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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.

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Advantages

Water can be supplied to any point  from at least two directions.

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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.

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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

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- 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

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 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.

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PALMA PEREZ DEEPWELL MLANG, NORTH COTABATO

Typical Pump to Reservoir Set up Typical Pump to Reservoir Set up

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