Lecture 1 Water Distribution Systems By: Eng. Ayman Afifi March 2009

Water System System Efficiency Input Output 2 Any System consists mainly of the following three phases: Input Processing Output System Efficiency The ability of an existing or planned water supply and distribution system to perform adequately - that is, to fulfill appropriately its intended purpose - under the widest possible range of likely operating condition, particularly those that are expected to occur during its working life, is a crucial system characteristic. 2

Water System Capacity Technical capacity means that the water system has the necessary technical infrastructure and competent trained staff needed to comply with drinking water regulations. Financial capacity means that the water system possesses the financial resources needed to comply with drinking water requirements for both the short and long term. Managerial capacity means that the water system has the institutional and administrative resources needed to comply with drinking water regulations 3

Types of transmitted water : Clean water: Source: Water wells, lakes,..etc. Transportation system: mostly under pressure (using pumps). Wastewater: Source: domestic, agriculture, industrial usage. Transportation system: by gravity. 4 4

Water Distribution System 5

Sources of Potable Water Untreated water (also called raw water) may come from groundwater sources or surface waters such as lakes, reservoirs, and rivers. The raw water is usually transported to a water treatment plant, where it is processed to produce treated water (also known as potable or finished water). 6

Transport Facilities 7 Moving water from the source to the customer requires a network of pipes, pumps, valves, and other appurtenances. Storing water to accommodate fluctuations in demand due to varying rates of usage or fire protection needs requires storage facilities such as tanks and reservoirs. Piping, storage, and the supporting infrastructure are together referred to as the water distribution system (WDS). 7

Water Distribution System Components of distribution network: Wells. Reservoirs. Pipelines. Booster pumps. Valves. 8

Types of Water Distribution System Gravity system. Pumping system. Pumping system with storage. The aim of all these systems is to obtain an adequate pressure at various points in the distribution system. The choice of the system depends upon the topography of the area of distribution and its elevation with reference to the source of the supply. 9

Gravity Systems This system is the most dependable technique provided. There are multiple well-protected conduits carrying the flow to the community. The gravity system is the most reliable. This system is useful in hilly areas where the source of supply is located substantially above the level of the city, such that adequate pressure is obtained in the network directly. 1010

Gravity Systems 1111 11

Gravity Systems Advantages Disadvantages No energy costs. Simple operation Low maintenance costs. No sudden pressure to changes. Gravity system is less flexible for future extension. Small gradients available for friction losses require large diameters within the whole system. Longer pipelines are necessary. High pressure for fire fighting requires use of motor pumping. 1212

Pumping Without Storage System Pumped supply systems operate without or with limited water storage (water towers) in the distribution system. With direct pumping to the system, they have to follow variations in water demand. Proper selections of units have to be done in order to optimize energy consumption, including reserve-pumping for irregular situations. 1313

Pumping Without Storage System 1414 14

Pumping Without Storage System Advantages Disadvantages Permitting increased pressure for fire fighting. Power failure and pressure will fluctuate substantially with variation in flow. The flow must be constantly varied to match an unpredictable demand. Increasing power costs. 1515

Pumping With Storage System It is the most common method of distribution. Water is pumped at a more or less uniform rate with flow in excess of consumption being stored in elevated storage tanks distributed throughout the system. During periods of high demand, the stored water augments the pumped flow, thus helping to equalize the pumping rate and maintain more uniform pressure in the system. Advantages: Economical to pump only during off-peak hour to minimize powering costs Pumping with storage system is the most common system for large distribution areas. 1616

Pumping With Storage System 1717 17

Methods of supply of water Water can be supplied to the consumers by the following two systems: Continuous system. Intermittent system. 1818

Continuous system In this system of supply, water is supplied to the consumers all the twenty- four hours. This system is possible only when there is sufficient quantity of water available from the source. Advantages of continuous system: Consumers don’t have to store water, since it is continuously available at the tap. Water always remains available for fire fighting. 1919

Intermitted system In this system of supply, water is supplied to the consumers only in pre-selected hours during the day. Hours of supply depends on demand, culture and distribution of needs. Advantages of intermitted system: Provide only needed water. Less central storage tank volume needed. Disadvantages of the intermitted system: On house storage is obligatory. Water quality in house tanks is affected with time. Pipe diameters are larger than the ones used in continuous system. Too many valves are needed in the system. 2020 20

Configuration of Distribution Networks 1. Serial network This network is without branches or loops. It has one source, one dead end and a couple of intermediate demand nodes. It’s usually used in un-organized developed cities. 2121

Serial Network Advantages of the Serial Network: Pressure and flow can be easily calculated at any point. Few valves are required to keep the system working. Pipe diameters are calculated relatively to the existing population. Disadvantages of the Serial Network: Maintenance works cause termination of the water supply in the whole system. Dead-ends increase pressure at the system which may cause, if exploded, a huge damages that could affect the entire efficiency of the system. 2222 22

Configuration of Distribution Networks 2. Grid network Consists of demand points that are supplied from more than one pipe. Flow direction is determined by the system operation and much less by its layout, thus it is not fixed which means that the location of critical points may vary in time. 2323

Grid network Advantages of the Serial Network: Maintenance work is much easier and cause no break to the entire system. Water for emergencies like fire is easier to provide by controlling the valves in the system. Less energy loss and adequate water pressure. Disadvantages of the Serial Network: Cost a lot due the number of pipes and network fittings. Water pressure at every point is always varying with time and relatively connected to the water consumption. 2424 24

Questions