Design Of Water Distribution System

COMPARISON BETWEEN YOUR HOUSEHOLD AND THE DWA AVERAGE* HOUSEHOLD Your House

DWA Average

Interior per capita gallons per day

135

Exterior per capita gallons per day

72

http://www.dwa.org/water_info/w_average_... For the entire USA, one site said "101 gallons per capita (person) per day (gpcd), for both indoor and outdoor water use in a single-family residence." http://www.cob.org/documents/pw/utilitie... This site, from the U.K. gives litres per day of domestic water consumption: http://www.sustainable-development.gov.u... 1 year ago 100% 1 Vote

What fixtures use the most water in my home? Toilet flushing, using the faucet, and washing laundry are all things we do around the home that use water. Some of these fixtures require differing amounts of water to operate effectively. If your home or apartment was constructed before 1993, you likely have fixtures installed that sometimes can use twice as much water as homes or apartments that were built after 1993. Fixture Type Pre-1993 Low-Flow Toilets (gallons per flush- gpf) 3.5 1.6 Urinals (gallons per flush- gpf) 3.0 1.0 Faucets (gallons per minute- gpm) 3.0 2.5 Showerhead (gallons per minute- gpm) 3.0 2.5 Washing Machines (gallons per load- gpl) 40.0 25.0 Indoor Water Use Per Capita Clothes Washer, 21.7% Dishwasher, 1.4% Faucet, 15.7% Shower, 16.8% Toilet, 26.7% Leak, 13.7% Other Domestic, Bath, 1.7% 2.2% Source: American Water Works Association

rate your water usage. Gallons Per Person

Per Day Rank Comments <80 gal/day Excellent Wow! You use water wisely. Please share your conservation techniques with friends and neighbors. 80 . 100 gal/day Good Good Job! You use less water than the average Maryland citizen. Look at the conservation tips below to learn how you can conserve even more water. 101 . 120 gal/day Fair You use more water than the average Maryland citizen. Read the conservation tips below to learn how you can conserve water. >120 gal/day Poor You use a lot of water. Read the conservation tips below to learn how to conserve water in the home. HOW CAN I CONSERVE WATER? Check for Leaks Low Consumption Toilet*** 1.6 flush Conventional Showerhead* 3-10 min Low-Flow Showerhead 2-2.5 min. Faucet Aerator* 3-6 min. Flow Regulating Aerator 0.5-2.5 min. Top-Loading Washer 40-55 load Front-Loading Washer 22-25 load Dishwasher 8-12 load * Manufactured before 1978 ** Manufactured from 1978 to 1993

Household Water Usage What is average? The water industry estimates that an average person uses 3,000 gallons of water monthly, so a family of 4 would use 12,000 gallons, for bathing, cooking, washing, recreation and watering. But a lot of factors come into play when calculating average use so, in reality, one person's usage may be a lot higher or lower than another person's. Here are some things to think about, if you suspect your water bill is too high. • •

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Households with backyard swimming pools are likely to see a spike up in water use in months when the pools are filled and filtered. Households with lawns or gardens must factor in the amount of water sprinkled on grass, flowers and vegetables. Outdoor watering uses 5 to 10 gallons per minute. So in 10 or 20 minutes, you may use 100 gallons – the amount industry experts estimate is used by an average person each day for all personal water needs! If the climate turns unseasonably dry, expect to use even more water to keep your garden alive and your grass green. The number of people in the household is an important factor. Water use generally rises if your family grows, if Uncle Harry moves in for a week or if you host a birthday party for 20 guests.

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A family with fashion conscious teen-agers probably washes more clothes more often than an older person who lives alone. More water is used per load when the machine is set on high. If you take a tub bath, you will use about 36 gallons of water, compared with the 25 to 50 gallons required for a shower. New showerheads, however, reduce the water used in an average shower to just 2 gallons per minute versus 5 or 6 gallons that spurt out of older showerheads. One toilet flush will use 5 to 7 gallons unless it is in a new home where 1.5 gallon comm

Overall, per capita water usage in Fort Collins and Loveland was similar, during the period 1998-2007. On average, Fort Collins consumed more gallons of water per person per day than Loveland (176 gallons per person per day, compared to 161 in Loveland).

Data Tables: Per Capita Water Consumption (Gallons Per Person Per Day) Fort Collins

Loveland

1996

203

176

1997

188

163

1998

196

176

1999

185

161

2000

211

204

2001

198

188

2002

183

161

2003

154

149

2004

146

139

2005

155

158

2006

172

143

2007

162

127

Number Of People In Residence

1

Bathroom Water Use Daily Showers In The Residence

1

Average Shower Time In Minutes

6.3

Shower Head Flow Rate (3.8 std. 1.6 res.)

3.8

Total Weekly Baths In Residence

0

Toilet Water Use

Average Number Of Flushes Daily Per Person

4

Gallons Per Flush (5 std. 1.6 res.)

5

Faucet Water Use Average Number Of Times Each Person Uses Faucet Daily

5

How Many Minutes Each Use

.5

Dishwashing Water Use How Many Times Are Dishes Washed By Hand Daily

1

How Many Minutes Each Use

5

How Many Dishwasher Loads Each Week

7

Gallons Per Dishwasher Load

15

Laundry Water Use How Many Loads Of Laundry Each Week

7

How Many Gallons Each Load

55

Lawn Water Use How Many Times Is The Lawn Watered Each Week

7

For How Many Minutes Each Time

30

How Many Minutes For Other Outdoor Use Each Week

10

Reset Form

Calculated Results Bathroom

24

Lawn Watering

450

Toilets

20

Other Outdoor Uses

14

gallons gallons gallons gallons

Faucets

8

Laundry

55

Dishwasher

15

Hand Washing Dishes

15

gallons gallons gallons gallons

COMPARISON BETWEEN YOUR HOUSEHOLD AND THE DWA AVERAGE* HOUSEHOLD Your House

DWA Average

Interior per capita gallons per day

137

135

Exterior per capita gallons per day

464

72

Total Per Capita Gallons Of Water Used Per Day Per Month Per Year CE 516

Design of Water Distribution Systems In this section, we have learned how to size pipelines and pumps for pipe networks. We will now examine some of the practicalities which need to be considered when designing such closed conduit systems. This is a review of section 2.5 in your text (which you should read). The primary function of water distribution systems are to 1. meet the water demands of users while maintaining acceptable pressures in the system 2. supply water for fire protection at specific locations within the system, while maintaining acceptable pressures for normal service. 3. provide sufficient level of redundancy to support minimum level of service during emergency conditions (i.e. power loss or water main failure.) Components The components of a water distribution system include: • pipelines - carry water from the treatment facility to the users.

transmission mains - the largest pipes which carry flow from the water treatment facility to the network. These pipes are often greater than (D > 600 mm). feeder mains - (pipelines which feed flow from the transmission main to the individual pipe networks of every service area (D _ 400 - 500 mm) distribution mains - the grid of pipelines which provides service to all users (D _ 150 - 300 mm) service lines - pipelines which go from the distribution mains to the individual house/facility. The individual lines are sized as per momentum equation (DarcyWeisbach) and energy equation (head loss equation.) Closed Conduit Flow 1 of 12 Design of water distribution systems CE 516

Components (continued) • pumps - maintain required pipeline service pressure. Because of variable demand requirements multiple pumps or pumps with variable motors are often required. booster pumps - maintain required service pressure along long pipelines fire-service pumps - provide additional capacity for emergency situations Pumps operate at the intersection of pump performance and network system curves and must adjust to highly variable demand. As such, multiple pumps may be required for steady, cyclical, and emergency demands • storage facilities - accommodates demand fluctuation by storing excess water until it’s necessary ground storage - ground level storage which discharge water to the system with a pump elevated storage - storage tank at the elevation required to deliver

water at required pressure (or head). • Valves - required for removing components and rerouting flows • Meters - required for monitoring flows Closed Conduit Flow 2 of 12 Design of water distribution systems CE 516

Component Design Life The preferred design life for the various components of water supply systems is given with the following table (Chin, Table 3.11) Component Design Period Design Capacity (years) Sources of supply River indefinite Max daily Wellfield 10-25 Max daily Reservoir 25-50 Average annual Pumps Low-lift 10 Max daily High Lift 10 Max hourly Water Treatment 10-15 Max daily Service Reservoir 20-25 Working storage + fire + emergency Distribution system Pipe or Conduit 25-50 Max daily + fire OR max hourly demand Distribution Grid Closed Conduit Flow 3 of 12 Design of water distribution systems CE 516

Operating Pressure of System The required system pressure demands on several considerations listed below: • excellent flow to a 3 story building requires 290 kPa • adequate flow for residential areas requires 240 kPa • adequate flow to a 20 story building requires 830 kPa* *Please note this isn’t desirable because of waste and leak, instead most tall buildings have their own on site pumps. Generally, pressures of greater than 650 kPa should be avoided. • adequate flow to most systems recommends 410-520 kPa ordinary consumption for 10 story buildings

adequate service for sprinklers in buildings of 4-5 stories adequate fire hydrant service adequate margin for fluctuations due to clogging and other losses Closed Conduit Flow 4 of 12 Design of water distribution systems CE 516

Water Demand Demands of the entire population must be considered before designing a water distribution system. Possible demand sources include: • residential • commercial • industrial • public The average city requires 660 liters/day/person. The distribution of demand between all the possible sources is given in the table below. Typical distribution of water use for an average city (Shin, 2000, Table 3.4) Category Average use Percent of total (liters/day)/person Residential 260 Commercial 90 Industrial 190 Public 70 Loss 50 Total 660 Closed Conduit Flow 5 of 12 Design of water distribution systems CE 516

Water Demand (continued) The distribution of average per capita rates among 292 water supply systems in the U. S. that serve 95 million people is given in the table below. Average distribution of per capita water demand (Shin, 2000, Table 3.5) Range Number of Percent of total (liters/day)/person systems 190-370 30 8 380-560 132 34 570-750 133 34 760-940 51 13

950-1130 19 5 >1140 27 7 Please note: these figures are based on 392 US water supply systems serving 95 million people (1984 Water Utility Operating Data, 1986 AWWA) Closed Conduit Flow 6 of 12 Design of water distribution systems CE 516

Water Demand Projections When planning for a water supply system, the water demand at the end of the network design life is generally used as the basis for the project design. Because the demand of the system 20 years in the future is not known, it is necessary to make some kind of prediction or forecasting about the municipality growth. A variety of Forecasting models exist, including: • aggregate models - treat the population as a whole • disaggregate models - break up the population into groups and predict the growths of each group. An example of this is cohort analysis (Sykes 1995) which segregates age and gender. These models require large quantities of data. • empirical models - are based solely on data. Please note that after 10 years, empirical models are as reliable as disaggregate models. Population growth is not generally steady and tends to grow at varying rates. Closed Conduit Flow 7 of 12 Design of water distribution systems CE 516

Geometric growth phase - occurs when there are wide open spaces and is modelled with Arithmetic growth phase - occurs after the initial growth has leveled off and is modelled with

Declining growth phase - occurs when growth becomes limited by available resources Each of the above phases is generally limited to 10 years in duration. For situations when a longer projection is required a long term projection can be approximated with an S-curve (most common used is a logistic curve) Please note, use existing data to determine a & b. Please note, that for projections of less than 10 years a 10% error can be expected, but for projections greater than 20 years a 50% error can be expected. Closed Conduit Flow 8 of 12 Design of water distribution systems CE 516

Demand Variations The demand in a water distribution system varies, daily, weekly, seasonally, and in the case of emergencies such as fires. Typical daily variations are given in the below figure (Chin, Figure 3.23) Closed Conduit Flow 9 of 12 Design of water distribution systems CE 516

The range of demand conditions are specified with peaking or demand factors. An example of the demand factors is found in the below table (Chin, Table 3.6). Condition Range of Typical demand factors value Daily average in maximum month 1.1-1.5 Daily average in maximum week 1.2-1.6 Maximum daily demand 1.5-3.0 Maximum hourly demand 2.0-4.0 Minimum hourly demand 0.2-0.6 In emergency situations as a result of fires the demand may increase significantly. The most common method for estimating peak demands due to fires is a method proposed by the Insurance Services Office (ISO, 1980). Their method estimates

the Needed Fire Flow, NFF, with NFFi = CiOi(X + P)i where C is the construction factor O is the occupancy factor X is the exposure factor P is the proximity factor i is the location where the flow is needed The maximum needed fire flow is less than 45,000 L/min Please see Chin for a more complete discussion of needed fire flows and the required coefficients Closed Conduit Flow 10 of 12 Design of water distribution systems CE 516

Required fire flow durations to satisfy insurance requirements (Chin, Table 3.10) Required fire flow Durations (L/min) (hours) <9,000 2 11,000-13,000 3 15,000-17,000 4 19,000-21,000 5 23,000-26,000 6 26,000-30,000 7 30,000-34,000 8 34,000-38,000 9 38,000-45,000 10 Closed Conduit Flow 11 of 12 Design of water distribution systems CE 516

Example A water-supply system is being designed to serve a population of 200,000 people, with an average per capita demand of 600 L/day/person and a needed fire flow of 28,000 L/min. If the water supply is to be drawn from a river, then what should be the design capacity of the supply pumps and water treatment plant? For what must be kept in the service reservoir to accommodate a fire? What

should the design capacity of the distribution pipes be? Solution assume: a) find design capacity given: b) determine required flow duration and volume c) determine design capacity for pipes Closed Conduit Flow 12 of 12 Design of water distribution systems

The purpose with a domestic water supply system is to provide the consumers with enough hot and cold water. Common in old buildings is the system with gravity storage tanks on the top floor of the building. More common in new systems are pressurized tanks connected to the supply pumps.

Domestic Water Supply with Gravity Tank The domestic water supply system with gravity tank is presented below:

For proper operation of the system, the gravity tank is located at least 30 ft or 10 m above the highest outlet or consumer. In tall buildings it's necessary to use pressure reducing valves in the lowest floors before the fittings. The volume of the tank must be designed to compensate for the limited capacity of the supply lines. The tank fills up when the consumption of hot and cold water is lower than the capacity of the supply lines - and the tank is emptied when the consumption is higher than the supply lines capacity. A drawback with the system with the open gravity tank on the top floor is the potential danger of freezing during winter conditions. Huge tanks will also influence the construction of the building.

Domestic Water Supply with a Pressurized Tank

The domestic water supply system with a pressurized tank is presented below:

The pressurized tank is partly filled with air behind a membrane. The air compensates for pressure variations during consumption and during supply pump starts and stops. The pressurized tank has a limited compensating capacity for shortage in main supply lines. Sponsored Links

Hot and Cold Water Pipes Sizing Recommended dimensions of hot and cold water pipes Sponsored Links The table below can be used to determine the maximum numbers of draw offs served by a pipe:

Maximum number of draw offs served Nominal bore of pipe Flow pipes

•

Return pipes

in

Steel pipe (mm)

Copper pipe (mm)

Head up to 20 m (70 ft)

Head over 20 m (70 ft)

1/2

15

15

1

1-2

1-8

3/4

20

22

2-4

3-9

9 - 29

1

25

28

5-8

10 - 19

30 - 66

1 1/4

32

35

9 - 24

20 - 49

67 - 169

1 1/2

40

42

25 - 49

50 - 79

170 - 350

2

50

54

50 - 99

80 - 153

2 1/2

65

67

100 - 200

154 - 300

Basins, Zinks, showers and similar are regarded as 1 draw off

The table below indicates sewage pipe capacity in gpm: Carrying Capacity of Sewer Pipe (gallons per minute)

Size of pipe (inches)

Decline per 100 ft pipe (feet)

1

2

3

6

9

12

24

36

3

13

19

23

32

40

46

64

79

4

27

38

47

66

81

93

131

163

6

75

105

129

183

224

258

364

450

8

153

211

265

375

460

527

750

923

9

205

290

355

503

617

712

1006

1240

10

267

378

463

655

803

926

1310

1613

12

422

596

730

1033

1273

1468

2076

2554

15

740

1021

1282

1818

2224

2464

3617

4467

18

1168

1651

2022

1860

3508

4045

5704

7047

24

2396

3387

4155

5874

7202

8303

11744

14466

27

4407

6211

7674

10883

13257

15344

21770

26622

30

5906

8352

10223

14298

17717

20204

28129

35513

36

9700

13769

16816

23760

29284

33722

47523

58406

The discharge rate is based on clean water and half filled pipes.

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1 gal (US)/min = 6.30888x10-5 m3/s = 0.0227 m3/h = 0.06309 dm3(liter)/s = 2.228x10-3 ft3/s = 0.1337 ft3/min

The table below can be used to indicate cold water storage per occupant: Storage per occupant Type of building liters

gal

Factories (no process)

10

2

Hospitals, per bed

135

30

Hospitals, per staff on duty

45

10

Hostels

90

20

Hotels

135

30

Houses and flats

135

30

Offices with canteens

45

10

Offices without canteen

35

8

Restaurant per meal

7

1.5

Schools, boarding

90

20

Schools, day

30

7

The Water Supply Fixture Units - WFSU - are used to determine the water demand in water supply systems. One WFSU for a singel unit corresponds to one GPM.

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1 WSFU = 1 GPM

This conversion can only be used for one or a few fixtures. When the total amount for many fixtures are added up, the number must be compensated due to the intermittent use of the fixtures. This is normal taken care of in the tables available for sizing supply pipe lines. When special equipment or manifolds are sized the table below can be used to indicate the flowrate. Note that the minimum flow rate can never be less than the fixture with the largest demand. The tables below can be used to estimate the demand in the water supply system when the load in WSFU is known. There are tables for systems with and without flush valves.

Water Supply System without Flush Valves WSFU

GPM

ft3/min

liter/sec

1

3

0.41

0.19

2

5

0.68

0.32

4

8

1.07

0.51

8

12.8

1.71

0.81

15

17.5

2.3

1.1

30

23.3

3.1

1.5

50

29.1

3.9

1.8

Water Supply System with Flush Valves WSFU

GPM

ft3/min

liter/sec

5

15

2

1

7

19.8

2.7

1.3

10

27

3.6

1.7

15

31

4.1

2

20

35

4.7

2.2

30

42

4

1.9

50

50

6.7

3.2

Probably Water Supply Diagram The Drainage Fixture Unit Values (DFU) are defined by the Uniform Plumbing Code (UPC), and can be used to determine the required drainage capacity from the fixtures and their service systems.

Minimum Size

Drainage Fixture Unit Values (DFU)

Individual Appliance, Appurtenance or Fixture (inch)

Private Installations

Public Installations

Bar sink

1 1/2

1

1

Bathroom (water closet, lavatory, bidet and tub or shower)

6

-

-

Bathtub

1 1/2

2

2

•

Bidet

1 1/4

1

Bidet

1 1/2

2

Clothes Washer

2

3

3

Dishwasher, domestic

1 1/2

2

2

Drinking fountain

1 1/4

0.5

0.5

Floor drain

2

2

2

Shower

2

2

2

Laundry tub

1 1/2

2

2

Lavatory

1 1/4

1

1

Bar sink

1 1/2

1

Kitchen sink, domestic

1 1/2

2

2

Laundry sink

1 1/2

2

2

Service or mop basin

2

Urinal

2

2

2

Water closet with gravity tank

3

3

4

Water closet with flushometer tank

3

3

4

3

1 WFSU = 1 GPM = 3.79 liter/min

Note that this conversion is only true for one or a few fixtures. Since the fixtures in a system are never used all at the same time, the total units (capacity) achieved by adding the numbers for all fixtures must be compensated for intermittent use if we want a realistic estimate of the total drainage load.

Both vertical and horizontal drainage pipes must be supported properly. Recommended maximum distances between the hangers are indicated in the table below. Distance between Supports (ft) Piping Material Horizontal Pipe

Vertical Pipe

ABS plastic

4

4

Galvanized steel

12

15

DWV Copper

10

10

Cast Iron

5

151)

PVC plastic

4

4

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Related Topics •

Water Systems Hot and cold water systems - design properties, capacities, sizing and more

The capacity of vertical downspouts draining roof areas can be found in the table below. Downspouts Size

Roof Area

mm

inches

m2

ft2

50

2

65

700

65

2 1/2

120

1300

80

3

205

2200

100

4

430

4600

150

6

1255

13500

Both vertical and horizontal drainage pipes must be supported properly. Recommended maximum distances between the hangers are indicated in the table below. Distance between Supports (ft) Piping Material Horizontal Pipe

Vertical Pipe

ABS plastic

4

4

Galvanized steel

12

15

DWV Copper

10

10

Cast Iron

5

151)

PVC plastic

4

4

Each fixture in a water supply system represents a certain demand of water. The table below can be used to indicate the normal supply requirements of common fixtures.

Minimum Supply Pressure

Flow rate Fixture (gpm)

(l/min)

(psi)

(kPa)

Aspirator

2.5

10

8

55

Bathtub faucet

5

19

8

55

Bidet

2

7.5

4

28

Combination fixture

4

15

8

55

Dishwashing machine

4

15

8

55

Drinking fountain jet

0.75

3

8

55

Laundry faucet 1/2"

5

19

8

55

Laundry machine

4

15

8

55

Lavatory faucet, ordinary

2

7.5

8

55

Lavatory faucet, self closing

2.5

10

8

55

Shower head

5

19

8

55

Shower, temperature controlled

3

10

20

138

Sink 3/8", 1/2"

4.5

17

8

55

Sink 3/4"

6

23

8

55

Urinal flush valve

15

56

15

110

Water closet with flush valve

35

132

25

170

Water closet with gravity tank

2.5

10

8

55

Water closet with close coupled tank, ballcock

3

11

8

55

Adding up the numbers to cover all fixtures in a system would give the total demand when all fixtures are used at the same time. This is almost never a realistic situation for a supply system. A reasonable estimate must be made based on the simultaneously demand of the fixtures

As a rule of thumb the following velocities can be used in design of piping and pumping systems for water transport: Pipe Dimension

Water

inches

mm

m/s

ft/s

1

25

1

3.5

2

50

1.1

3.6

3

75

1.15

3.8

4

100

1.25

4

6

150

1.5

4.7

8

200

1.75

5.5

10

250

2

6.5

12

300

2.65

8.5