Water System Design Manual
Pumps should have valves adequate to permit satisfactory operation, maintenance, and
equipment repair. There should be isolation valves on the suction and discharge side of the
booster pump. Other appurtenances include:
Check valves on the discharge side of each booster pump.
End connections for booster pumps, pressure vessels, and large equipment should have
flexible flanged coupling adapters for larger units and threaded unions for smaller units.
They will simplify maintenance and provide flexibility in installation.
Pump control valves and surge anticipation valves, as needed. They will prevent
destructive hydraulic transients during normal and emergency pump start or stop.
The BPS should have a visible external alarm light (with a battery backup) designed to indicate
pump failure or low-pressure conditions in the BPS service area. If practical, the BPS alarm
system should be connected to a 24-hour operations center or an automatic signal transmitted by
phone to an authorized operator. The BPS should also have a system to monitor suction pressure.
It will ensure the pumps do not operate with insufficient net positive suction head, or at the
expense of operating pressures in the distribution system from which they are drawing water.
10.4.5 Cross-Connection Control
When designing or installing individual service booster pumps, the engineer should recognize
that the premises the pumps will serve is a cross-connection hazard. Under normal
circumstances, the pressure on the downstream side of the booster pump is higher than system
pressure. However, the check valve(s) normally provided could fail or leak, causing water from
the premises to backflow through the pump and into the distribution main. This is an unavoidable
or uncorrectable cross-connection situation (WAC 246-290-490(4)(e)(iii)). To prevent it from
occurring, the purveyor may require the:
Water system to be protected by a backflow prevention device commensurate with the
degree of hazard.
Water to be supplied through an approved air gap prior to being pumped.
Consumer to pay for the backflow prevention device, its inspection and testing.
Water that enters the consumer's premises is "used water." Therefore, any piping arrangement
that allows pressure relief must not be directed back into the distribution system (WAC 246-