Water Supply Municipal Water Demand Civil Engineering Department Faculty of Engineering and Technology The University of Jordan Instructor: Ghada Kassab, PhD

2 Design of water supply system 1. Design period: the number of years for which the system is to be adequate. Long design periods are justified when; i.Population growth is small ii.Stage wise expansion is difficult. iii.The interest rate is low. iv.Structures are difficult and costly to enlarge, such as dams, canals. Design periods of years are generally considered long design periods. Structures that are easily expanded such as water treatment plants usually have design periods of years.

3 2.Design population: The number of persons to be served 3.Design flow: the rates of consumption for the residential, commercial, industrial and public areas. 4.Design areas: the area to be served by the system. 5.Design capacity: the capacity of the  Water treatment plant  Intake structures for surface water.  Lift pumps located in or near the intake structure.  Canals to treatment plant  The storage reservoirs.  Pumps that pumps water to the distribution system.

4 Since; reservoirs, intake structures, transmission system, size of water treatment plant and piping to connect treatment facilities to customers all depend upon on water demand. The amount water needed or used is critical in the planning and design of a water supply system. The amount of water used is based on type and umber of customers. Industrial use Commercial uses o Hospitals L/bed. day o Schools L/student. day o Hotels L/bed. day. Domestic uses

5 Estimation of water demand requires variety of data 1.Layout of new development 2.Demographic and land use data. This is data about the customers and how customers use their property. Including: o Population numbers o Expected population growth o Types of customers (industrial, commercial, etc. o Location of the customers.

6 3.Consumption data (estimated water use by customers). That include o Per capita daily water demand (L/capita.d) o Water use pattern o Estimate change in water consumption patterns (use of water conservation strategies.) 4.Climatic data: seasonal temperature and precipitation Data related to existing system is usually collected as well, which include Piping network Process drawings for water treatment plant Water levels in storage tanks. Pumping rates. etc.

7 Source of information 1.Historical records of water usage o Billing records, these will provide avg. Data o Water level changes in reservoirs. 2.Land use data, based on customer type 3.Customer density Other factors such as unaccounted for water need to be taken into consideration

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9 Information stated earlier generally provide average flow rates for water usage. Average flow rate provides an idea of the amount of water that needs to be treated and transported, but the actual design needs to be able to handle expected daily and seasonal variations in water flow.

10 Quantifying water demand Average day demand Maximum day demand Average day demand (ADD) Represent to total water demand that is exerted on the system by all users on a normal day. It is recommended that historical data and water use records are used to determine ADD of a community If sufficient data is unavailable to develop a reasonable estimate of water use, a published average per capita water demand may be used instead.

11 Maximum day demand (MDD) The MDD is the maximum water demand that can be expected from the community on any given day. The MDD can be determined from historical waster use data. MDD value should accurately represent the demand during peak demand periods, and care must be taken to avoid choosing an MDD value that is associated with a unique not repeated event like main break. If representative waster use data is not available, peaking factors can be use to predict MDD.

12 Daily peak factor depends on size and characteristics of community It ranges from 1.5 to 4.0 Small communities are assigned larger peaking factors, because they are expected to have higher levels of flow variations.

13 Peak hour demand PHD The PHD represent the maximum hourly demand experienced The PHD can be determined using historical water use data, if available. Otherwise, we use hourly peaking factors.

14 Design flows I.Treatment It is recommended to design water treatment equipments on Maximum day demand For a design period of years Taking into account Treatment system cleaning (backwashing) Known leakage in the distribution system. The design flow must be determined carefully to avoid Under sizing Inadequate treatment over sizing High capital cost

15 II. Distribution Distribution systems are designed to provide enough water: To satisfy peak hour demand of all users served by the system For a design period years.