Because most of our water service areas are not flat most water systems have multiple water pressure zones. A water pressure zone is a geographic section of a water distribution network that is determined by the elevation of the area served.

The pressure in the water system, known as hydraulic pressure, is created by gravity pulling a column of water downwards. At an average height of about 120 feet, water towers properly pressurize the water distribution pipes within a pressure zone.

Within a pressure zone, a minimum pressure is established by pumping stations or reservoirs. Water does not flow between pressure zones unless it flows from a higher pressure zone to a lower pressure zone, through a pressure reducing valve. Water pressure in a pressure zone typically ranges from 40 to 130 psi, but may be higher.


Most water systems are designed to utilize gravity to efficiently move water throughout the distribution system. When the use of gravity cannot be utilized, pumps take over to move the water.

The energy required to pump water is an extremely demanding component of water distribution system. Since electrical power for pumping is a major expense, the goal is to develop a system which minimizes pumping. Pump stations fall into two different categories. The first type lifts water from lower elevations to fill water reservoirs located at various high points. From there gravity takes over to supply customers at the lower elevations. For other areas where customers cannot be served by gravity, another option exists, the booster pump. These stations pump water to customers and help ensure adequate pressures are maintained at all times. CRWP members have numerous pumps and pump stations in various locations throughout their service areas. Distribution system operators don’t use all of the pumps in the system at the same time; rather they cycle them on and off based on the demand. Some pump stations will always have pumps running, i.e. booster pumps, while others may only be needed in the height of the summer water-use season. Many of our systems have pumps that automatically increase and decrease pumping capacity with shifts in water demand helping us save money on electrical costs.