Water Distribution Systems

Distribution systemsDesigned to adequately satisfy water requirements for combination of:

Domestic useCommercial UseIndustrial UseFire-fighting

Have to consider:

FlowPressureQuality

Distribution System Classifications

Branching System

Grid System

Combination system

System Type Advantages

Branching System

Grid System

Combination System

System Requirements

Commercial

Pressure greater than 60 psig typically required

Residential

Pressure of 40 to 50 psig

Tower Buildings

Intermediate booster pumps with storage tank on top

Velocities typically between 3 to 5 fps at peak flows

Select pipe sizes to avoid hig velocities

* Inch pipes recommended in areas were fire-fighting demands are expected. 6 inch pipe may be used if a grid type system is used and length between connections is lesss than 600 feet.

A typical distribution system layout

Hydraulic grade lines

Distribution Reservoirs and Service Storage

Storage reservoirs are used to meet fluctuating demands, to accommodate fire-fighting and emergency requirements, and equalize operating pressures.

Types of storage reservoirs:

Surface reservoirsStandpipesElevated storage tanks

Locate reservoirs and storage to maximize benefits. Usually near the center of use.

High enough to supply necessary pressure in the system

Modes of Operation

Demand light – pumping station will met needs in system and supply water to storage tank.

Demands high – both the tank and the pumping station will be needed to supply the flow