What is the typical city water pressure

How reverse osmosis booster pumps work

How reverse osmosis booster pumps work

The purpose of the reverse osmosis booster pump is to increase the water pressure into the RO unit.

Reverse osmosis is a pressure driven process; small reverse osmosis units will theoretically operate at very low pressure - up to 35 psi according to some membrane manufacturers - but the reality is you won't get a lot of water and product water quality will be compromised if the unit runs under 45 psi. A low inlet pressure will result in the unit producing more wastewater, producing less drinking water, filling the reservoir more slowly and producing poor quality water.

RO units run fine at a typical city water pressure of 60 psi, but they run even better with a small pump to raise the pressure to 80 psi or higher.

The picture above shows the three essential elements of the RO booster pump. The white object on the left is the transformer. It plugs into a standard electrical outlet and converts the voltage (most commonly 24 volts) into the pump. The big object is the pump The third device is the pressure switch. It monitors the water pressure in the storage tank of the reverse osmosis unit and switches the pump off and on again depending on the storage pressure. The most common cut-off pressure for under-home RO units is 40 psi.

The standard pump setting is shown above.The function of the pressure switch in the tank line is to cut off the power to the pump when the tank pressure reaches a preset value.Standard pressure settings typically deliver about 80 psi of pressure to the RO unit and shut down production when the tank pressure reaches 40 psi.These settings can be adjusted, but it is best to leave them at the factory settings.(Click the image for a larger version.)

Do you need a booster pump?

Most city water reverse osmosis users have enough city water pressure to run their RO unit nicely and they don't need a booster pump. For example, if your city water pressure is 60 psi or more, little can be achieved by adding a booster pump, if your pressure 50 psi or less, however, a booster pump will increase the RO unit more. You will have more water at a higher pressure in the accumulator and the tank will fill faster. The increased pressure will also improve the economics of the device (less wastewater will run) as well the quality of the water. RO units thrive under pressure.

Are all pumps the same?

Manufacturers often refer to pumps by the gallons-per-day output of the RO unit. The Aquatec 6800 pump pictured above is recommended for use with units with diaphragms that can handle up to 50 gallons per day. Larger diaphragms use a different one Model, Aquatec 8800, recommended.

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