Gary C. Tanko Well Drilling, Inc.
The trusted name in water well drilling, pump sales, service & installation since 1969.
Pressure Requirements
The pressure of the water delivered from the water system should be adequate to force the water through the piping system to the highest outlet. It must be adequate to properly operate modern water-using appliances. Most appliances, such as dishwashers and washing machines require at least 10 pounds per square inch (psi) at their inlet for proper operation. Lawn sprinklers usually require a minimum of 20 psi and sometimes up to 40 psi. The installation of water conditioning equipment, such as water softeners, results in a pressure drop in the system for different flow rates and must be considered in determining required pressure.
Water systems operate with their discharge pressure held between two predetermined settings. The most common systems are set to operate between 20 psi and 40 psi. This is adequate for most small homes where the pump and hydropneumatic tank are located in the basement, and where not more than two floors exist.
If the piping system is old and the inside diameters of the pipes are reduced due to deposits of rust or lime, the friction loss through the system will be great, and a higher pressure setting will be required. If the pump is located a distance from the house, and particularly if it is at a lower level, higher pressures are required. Some water systems are set to operate between 30 psi and 50 psi, and in unusual conditions, between 40 psi and 60 psi.
A sound, conservative method of determining the best pressure setting is to have a pressure of 10 psi at the inlet side of the fixture that is the highest and farthest from the pump, as measured when water is flowing through the fixture.
A water system is not adequate unless it produces enough pressure to distribute the water through the piping system to the point of usage, continuously and when other outlets are also using water.
