Ch. 12 Water Supply

• Normally buried or installed in utility manholes.
• If properly ind=stalled can be operated above ground through valve box.
• Some cases a special socket wrench on a reach rod needed to operate.

• Visually shows positions of gate or valve.
• Post Indicating Valve: Hollow metal post that houses valve stem. Has a plate that says open or shut.
• Outside Stem & Yoke (OS&Y): Has a yoke on the outside with thread system that opens & invisisble when closed.

Indicating & Nonindicating

At least once every year to keep them working.

So only small sections are cut off it is necessary to locate parts of the system for repairs.

• 6" diameter in resedential.
• Closely gridded by 8" cross-connecting mains at intervals no more than 600'.
• 12" mains on priciple streets in the long mains but cross-connecting at frequent intervals.

• Two or more primary feeders.
• Secondary feeders connect primary feeders & supply water from two directions to any point.

• Primary Feeders: Large mains, widespread, large quantity of water.
• Secondary Feeders: Intermediate-sized mains that run from primary to distributors.
• Distributors: Grid of small mains serving fire hydrants & blocks of consumers.

Circulating feed or looped line

• A hydrant that receives water from only one direction.
• Has a limited water supply.

Reduces the volume & pressure of the water flowing to the hydrant.

The movement causes friction & reduces water pressure.

They typically store large amounts of chlorine.

If there is a fire it could reduce the volume & pressure of water available.

• Uses water source from a higher elevation than the distribution system.
• Pressure only adequate when source is more than 100' higher than the distribution center.
• Ex. Alpine lakes & mountain reservoirs

• Mostly found in agricultural & industrial settings.
• One or more pumps move water from primary source to point if use.
• Disadvantages: Total dependence on pumps & electricity