About

• The purpose of distribution system is to deliver water to consumer with appropriate quality, quantity & pressure.
• Distribution system is used to describe collectively the facilities used to supply water from its source to the point of usage.

 

Requirement of good distribution system

• 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.
• It should be capable of supplying the requisite amount of water during fire fighting.
• 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 meter away or above the sever line.
• It should be fairly water tight as to keep losses due to leakage to the minimum.

 

Layout distribution network

• The distribution pipes are generally laid below the road pavement, and as such their layouts generally follow the layouts of roads.
• There are general, four different types of pipe networks; any one of which either single or in combination, can be used for a particular place.

 

Classification of networks

• Dead end system
• Radial system
• Grid iron system
• Ring system

 

Dead end system

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

Advanatge

• Relatively cheap
• Determination of discharge and pressure easier due to less number of valves.

Disadvantage

• Due to many dead ends, stagnation of water occurs in pipes.

 

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 rapidly ending towards the periphery.

Advantage

• It gives quick service
• Calculation of pipe size is easy

 

Grid iron system

It is suitable for cities with rectangular layout, where the water mains and branches are laid in rectangles.

Advantages

• Water is kept in good circulation due to absence of dead ends.
• In the case of break down in some section, water is available from some other direction.

Disadvantage

• Exact calculation of sizes of pipes are not possible due to provisions of valves on all branches.

 

Ring system

• The supply main is laid all alone the peripheral roads and sub mains branch out from the main.
• 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.

Advantages

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

 

Methods of water distribution

For efficient distribution system adequate water pressure required at various points.

Depending upon the level of source, topography of the area and other local consitions, the water may be forced into distribution system by following ways-

• Gravity system
• Pumping system
• Combined gravity and pumping system

 

Gravity system

• Suitable when source of supply is at sufficient height.
• Most reliable and economical distribution system.
• The water head available at the consumer is just minimum required.
• The remaining in the frictional and other losses.

 

Pumping system

• Treated water is directly into the distribution main out storing.
• Also called pumping without storage system.
• High lifts pumps are required.
• If power supply fails, complete stoppage of water supply.
• The method is not general used.

 

Combined gravity and pumping system

• Treated water is pumped and stored in an elevated distribution reservoir.
• Then supplies to consumer by action of gravity.
• The excess water during low demand periods get stored in reservoir and get supplied during high demand period.
• Economical, efficient and reliable system.