1. Lecture 3 Water Consumption

2. Water Consumption
The consumption or use of water, also known as water demand, is the driving force behind the hydraulic dynamics occurring in water distribution systems.
Anywhere that water can leave the system represents a point of consumption, including a customer's tap, a leaky main, or an open fire hydrant.
The three basic demand types are:
1. Customer demand is the water required to meet the non-emergency needs of users in the system.
2. Unaccounted-for water (UFW) is the portion of total consumption that is "lost" due to system leakage, theft, un-metered services, or other causes.
3. Fire flow demand is a computed system capacity requirement for ensuring adequate protection is provided during fire emergencies. 2

3. Water Consumption
Determining demands is not a straightforward process like collecting data on the physical characteristics of a system. Some data, such as billing and production records, can be collected directly from the utility but are usually not in a form that can be directly entered into the model. Once this information has been collected, establishing consumption rates is a process requiring study of past and present usage trends and, in some cases, the projection of future ones.
After consumption rates are determined, the water use is spatially distributed as demands, or loads, assigned to model nodes. This process is referred to as loading the model. Loading is usually a multi-step process that may vary depending on the problem being considered. The following steps outline a typical example of the process the modeler might follow:
Allocate average-2hr demands to nodes.
Develop peaking factors
Estimate fire and other special demands.
Project demands under future conditions for planning and design. 3

4. Baseline Demands
Most modelers start by determining baseline demands to
which a variety of peaking factors and demand multipliers can
be applied, or to which new land developments and customers
can be added. Baseline demands typically include both
customer demands and unaccounted-for water. 4

5. Data Sources 5 Pre-Existing Compiled Data
The first step in finding demand information for a specific utility should always include researching for the utility's existing data. Previous studies, and possibly even existing models, may have a wealth of background information that can save many hours of investigation.
However, many utilities do not have existing studies or models, or may have only limited resources to collect this type of information. Likewise, models that do exist may be outdated and may not reflect recent expansion and growth. 5

6. Data Sources 6 2. System Operational Records
Various types of operational records are available that can offer insight into the demand characteristics of a given system. Treatment facility logs may provide data regarding long-term usage trends such as seasonal pattern changes or general growth indications. Pumping logs and tank level charts contain data on daily system usage, as well as the changing pattern of demand and storage levels over time.
Water distribution systems may measure and record water usage in a variety of forms, including:
Flow information, such as the rate of production of a treatment or well facility.
Volumetric information, such as the quantity of water consumed by a customer.
Hydraulic grade information, such as the water level within a tank. 6

7. Data Sources 3. Customer Meters and Billing Records
If meters are employed throughout a system, they can be the best source of data for determining customer demands. Customers are typically billed based on a volumetric measure of usage, with meter readings taken on a monthly or quarterly cycle. Using these periodically recorded usage volumes, customers' average usage rates can be computed. Billing records, therefore, provide enough information to determine a customer's baseline demand, but not enough to determine fluctuations in demand on a finer time scale such as that required for extended-period simulations. 7

8. Cont. Data Sources
The most common method of allocating baseline demands
Is a simple unit loading method. This method involves
counting the number of customers [dunums of a given land
use, number of fixture units, or number of equivalent
dwelling units] that contribute to the demand at a certain
node, and then multiplying that number by the unit demand
[for instance, number of gallons (liters) per capita per day]
for the applicable load classification. For example, if a
junction node represents a population of 200, and the
average usage is 120 l/day/person, the total baseline
demand for the node would be 24,000 l/day. 8

9. Example - Demand Allocation
In a detailed demand allocation, a key step is
determining the customers assigned to each node. The
figure below demonstrates the allocation of customer
demands to modeled junction nodes. The dashed lines
represent the boundaries between junction associations.
For example, the junction labeled J-1 should have
demands that represent nine homes and two commercial
establishments. Likewise, J-4 represents the school, six
homes, and one commercial building. 9

10. Example - Demand Allocation
1010

11. Factors affect water consumption
Water cost
Country volume
Commercial and industrial system
Pressure in the network
Sewage system
Weather conditions and Climate
Tradition & habits

12. Water Consumption
Water consumption is initially split into domestic and non-domestic. The non-domestic consumption relates to the water used for industry and other commercial and public uses (shops, offices, schools, hospitals, etc).
Water demand is commonly expressed in cubic meters per hour (m³/h) or per second (m³/s), liters per second (l/s), or liters per capita per day (l / c /d or lpcpd).

13. Domestic Consumption
Domestic water consumption is intended for toilet flushing, bathing, showering, laundry, dishwashing and other less water intensive or less frequent purposes as cooking, drinking, gardening, car washing, etc.
In Gaza Strip, domestic water consumption varies from
80 l /c /d for some area to 120 l / c /d .

14. Domestic Water Consumption l / c / d
Domestic demand
According to the PWA, The target water demand to be achieved in 2025 is 150 l / c /d. The planned domestic water consumption by PWA is summarized in the following table.
Year
Domestic Water Consumption l / c / d
2007
110
2010
120
2015
135
2020
150
2025

15. Residential consumption water
The world average water consumption is 280 L/C/day
For Middle East area, the average water consumption is 120 L/C/day to 180 L/C/day
نوعية المياه
الكمية المطلوبة لتر/يوم/للشخص
الشرب
3 - 5
الطهي
5 - 10
الاستحمام
الوضوء
15-20
الحمامات
الغسيل
20 -30
الشطف
10 – 30
أخرى

16. Non-domestic Consumption
Non-domestic or commercial water use occurs in industry, institutions and offices, tourism, etc. Each of these categories has its specific water requirements.
- Industry
Water in industry can be used for various purposes: as a part of the final product, or for the maintenance of manufacturing processes (cleaning, flushing, cooling, etc).
The industrial consumption is largely dependable on the type of product and the technology used.
The industrial consumption is commonly expressed in liters per unit of product or raw material. The following table gives an indication for a number of industries.

17. Industrial demand Industry Liters per unit product
Carbonated soft drinks
1.5 – 5 per liter
Fruit juices
3 – 15 per liter
Canned vegetables/fruits
2 – 27 per kg
Bricks
Bricks 15 – 30 per kg
Paper
4 – 35 per kg
Textiles
100 – 300 per kg

18. Commercial demand
Commercial consumption in restaurants, shops, schools and other institutions can be assessed as a total supply divided by the number of consumers (employees, pupils, patients, etc.). Accurate figures should be available from local records.
Commercial unit consumption are given in the following table :
Purpose
Consumption
Schools
10 l / c / d
Hospitals
300 l / bed / d
Public Offices
40 l / employee / d
Restaurants
70 l / c / d
Social centers
10 l / c / d
Gardens
25 m3 / Donume / week
Cafeterias
35 l / c / d
Mosques
15 l / c / d

19. Other Commercial demands
نوعية المبنى
الاستهلاك لتر/يوم/شخص
المصانع (بها حمامات) 30
المستشفيات
300
بيوت العجزة
135
الفنادق
180
المطاعم 70
المكاتب 40
السينما والمسارح 15
المدارس 10
المطارات
صالات الاجتماعات
الكافتيريا 35
الحدائق
25 م3 للدونم في الأسبوع

20. الكميات المطلوبة (م3 / للدونم للعام)
Agricultural water
نوع المحصول
الكميات المطلوبة (م3 / للدونم للعام)
الحمضيات ري جزئي
500
الحمضيات بري كامل
1000
الجوافة والزيتون
300
الخضروات
700

21. Unaccounted for Water (UFW)
It’s an unavoidable component of water demand that is supplied ‘ free of charge ’.
Causes of UFW differ from case to case. Most often it is a leakage that appears due to improper maintenance of the network such as defective pipe joints, cracked and broken pipes, faulty valves and fittings. Other losses are related to the water that is supplied but not registered or paid for (under-reading of water meters, illegal connections, washing streets, flushing pipes, etc.)

22. How to measure UFW?
If meters are employed throughout a system, they can be the best source of data for determining customers consumption. Customers are typically billed based on a volumetric measure of usage, with meter readings taken on a monthly or quarterly cycle. Using these billing records the UFW water quantity can be easily calculated.
The UFW in the developing areas varies from 30 % to more than 50 % of the total water consumption.
According to PWA studies, the UFW is estimated as 30 % of the total water consumption up to year 2010, 25 % up to 2015 and 20 % up to 2020 and then will remain at the same percent.

23. الاستهلاك لتر/يوم/شخص
Total consumption
نوعية الاستهلاك
الاستهلاك لتر/يوم/شخص
سكني A
تجاري B
صناعي C
عام D
زراعي E
فقودات F
Total consumption is: A+B+C+D+E+F

24. Example
نظام لتزويد المياه يخدم منطقة سكنية عدد أفرادها 1000 شخص بالإضافة إلى مصنع، على مدار السنة كان مقدار
الاستهلاك الكلي لمياه الشرب 114,000 م3. قراءات العدادات بالنسبة للمصنع حددت استهلاك للمياه مقداره 38,000 م3. احسب متوسط الاستهلاك السكاني للفرد الواحد ثم حدد الاستهلاك اليومي المتوسط لكل نقطة استهلاك.

26. Water Quantities for Fire

27. In water network design for fire, the following criteria could be used:
The pressure at the fire hydrants (نقاط تغذية) is 20 m head with Q=60m3/hr
The time is two hour
Fire hydrant diameter is 10 cm
The water quantity for fire must be storage to fulfill the emergent need
The distance between the fire hydrant not more than 300 m in cities with middle density
The distance between the fire hydrant not more than 200 m in cities with high density
Fire numbers in the same time can be calculated by:
P is population number in thousands

28. Topographical Studies
Surveying maps should be prepared in which 3
items must be presented :
Contour Lines.
Master Plan ( Land Use ).
Location of water resources .

29. What we have done so far Preliminary Studies Demographical Data
Topographical Data
Water Consumption
Preliminary Studies
What we have done so far

30. Analysis of the Network
Preliminary Studies
Layout of the Network
Data Entry
Analysis of the Network
What’s Next ??

31. Allocation steps:
Draw network layout for the target year and pinpoint junctions and pipelines.
Draw areas around the nodes in a way that cover the entire area under consideration.
Determine the water demand type of each junction using the land use map prepared and determine the areas that are served by each junction.
Calculate the number of population served by each junction (using the area and the density)
Calculate the demand of each junction by multiplying the population by the average consumption per capita.
Specify other types of demand and allocate them to the nearest nodes.
The demand of each junction should be multiplied by a coefficient accounts for UFW in the design year.

32. Example:

33. Example:

34. Example 2

35. Area around nodes:

36. Demand over nodes
Domestic Consumption in the design year = 150L\c\day.
School consumption = 3 L\pupil\day
Mosque consumption = 11 L\prayer\day
UFW = 30%
# J
Elevation ( m )
Domestic
School
Mosque
Public
Area
Density
Population Q
# pupils
# Prayers
# Employees
( m² )
( l/2hr )
( l/d ) J1
10.5
1187
0.155
184
35,880
500
7150
J21
12.3
2331
359
70,005
1000
3900
J22
12.68
4127
640
124,800
1950
J32
14.44
1988
308
60,060
1746
225
11662
184*150*1.3

37. QUESTIONS