Free Shipping on most orders over $89
Shipping To:

What Is a Reverse Osmosis Booster Pump and How Does It Work?

Posted by John Woodard on November 30, 2023

under-sink RO system

Reverse osmosis (RO) filtration systems are one of the most popular water filtration methods available today. Used primarily in under-sink applications, RO systems remove an incredible number of contaminants when they operate efficiently. Some factors, however, can limit the efficiency of an RO system and render it less effective than it should be. One factor that can limit an RO system is incoming water pressure. When water pressure is low, more water will be wasted in the filtration process, and fewer contaminants will be removed from the filtered water. Reverse osmosis booster pumps ensure an RO system’s water pressure stays at a high enough level to perform optimally. Another factor that can come into play is osmotic pressure.  Osmotic pressure is the natural force of nature that creates osmosis. The higher the level of dissolved solids in the water, the higher the osmotic pressure will be.  To create reverse osmosis, we must overcome the osmotic pressure.  A level of dissolved solids (TDS) over 500 ppm should add a booster pump even if the feed supply pressure is good.  This will ensure there is enough pressure to provide optimal performance. Below you can find what a reverse osmosis booster pump is, how it works, if you need one, how to install one for your RO system, and a few of the best booster pump options.

What is a reverse osmosis booster pump?

A reverse osmosis booster pump enhances the water pressure of a reverse osmosis system. When water pressure leading into an RO system is too low, the system outputs very little water, and the water it filters is not as pure as it would be if the system was operating at peak performance levels. While municipal water supplies typically have enough water pressure to sustain an RO system, installing a reverse osmosis booster pump ensures that the system runs effectively regardless of incoming water pressure. RO booster pumps are especially effective against water with a concentration of TDS over 500 ppm.

How does a reverse osmosis booster pump work?

A reverse osmosis booster pump typically contains a diaphragm pump, a power supply, and a tank pressure switch. A diaphragm pump uses reciprocation in a diaphragm made of rubber or plastic to pump water from an intake to an outtake. The diaphragm works in cooperation with valves on both sides to increase the pressure of water as it flows through the pump. The transformer powers the pump and plugs directly into a standard wall outlet. To prevent the water pressure in an RO system from becoming too high, the pressure switch stops the current to the booster pump when the tank reaches a certain pressure.

Reverse osmosis systems require at least 50 psi to operate correctly, so booster pumps are essential for water supplies with low water pressure. RO systems push water through a semi-permeable membrane, where many contaminants are eliminated from water as it passes through. When not enough water pressure is present, the membrane is not effective at removing contaminants and not as much water passes through the filter. This leads to more water being wasted in the filtration process and more contaminants residing in the water that does make it through the filter.

Do I need a reverse osmosis booster pump?

If your water pressure is below 40 psi, you need a booster pump for your RO system to function properly. You should also consider getting a booster pump if your water pressure hovers between 40 and 50 psi or if TDS levels in your water are over 500 ppm. While RO systems will operate at 40 psi, having water pressure of at least 60 psi guarantees that your filtration is optimal. Not only will a higher water pressure make your RO system work faster, but it will also allow your filters to remove more contaminants while producing less wastewater.

low water pressure showing on gauge

How do I check my home’s water pressure?

You can check your home’s water pressure with a pressure gauge. Follow these few simple steps to get an accurate reading with a pressure gauge.

  1. Locate a test outlet. If you get water from a city water supply, you should use a pressure gauge on the outdoor spigot closest to your water meter. If you do not have an outdoor spigot, use the cold water supply line for your washing machine. If you get your water from a well, connect the pressure gauge to the fixture closest to the well’s pressure tank.
  2. Turn off all water outlets. Before testing, ensure that all water outlets, including sinks, showers, refrigerators, and washing machines, are not running. If water runs elsewhere while testing, the water pressure will decrease, and the test result will be flawed.
  3. Connect the pressure gauge. To connect a pressure gauge, simply screw it to the spigot with your hand. The gauge should seal the connection when screwed in by hand. If the connection leaks while testing, you may need to use pliers to tighten the gauge all the way.
  4. Test the water pressure. Once the pressure gauge is connected, turn the spigot on its maximum flowrate. The gauge will show you your home’s water pressure.
  5. Interpret results. Homes in municipalities with high water pressure have a water pressure regulator to prevent pipe damage. If your water pressure exceeds 80 psi and your home has a water pressure regulator, that is a sign that your regulator has failed. If your water pressure is below 50 psi and you have a reverse osmosis system, you will need a booster pump to increase its production.

Reverse osmosis booster pump vs water booster pump

A reverse osmosis booster pump provides pressure to a single RO system. A water booster pump provides water pressure to an entire house or commercial water supply. Because water booster pumps deal with a much higher volume of water than RO booster pumps, they are much bigger and more expensive. A water booster pump costs close to $1000, while you can purchase an RO booster pump for around $80 to $300. A water booster pump is necessary if low water pressure that is not caused by a leak impacts the effectiveness of a certain activity or appliance, like a weak stream of water from your shower. If low water pressure is only affecting your RO system, then an RO booster pump is the right choice for you.

Learn more: What is a Water Booster Pump and How Does It Work?

Reverse osmosis booster pump vs demand pump

Both RO booster pumps and demand pumps can be used with a reverse osmosis system, but they are used at different stages. Unlike an RO booster pump, a demand pump is used after the water is filtered and transported to the storage tank. Demand pumps increase water pressure on the output of an RO storage tank so that water can reach a point of use, such as a refrigerator. While RO booster pumps work with pretreated water, demand pumps work best with clean water.

Learn more: What is a Demand Pump and How Does It Work?

How do I install a reverse osmosis booster pump?

Installing a reverse osmosis booster pump is a straightforward process that can be done yourself. You should install the pump next to your RO system underneath your sink. Before you install, you will likely want to purchase a mounting bracket suitable for the size of your pump. To install an RO booster pump, you need to:

  1. Empty the water tank. This enables the pump to refill the tank and ensure the pressure switch is connected properly.
  2. Turn off water supply to your RO system and the RO storage tank valve. Open the connected faucet to release pressure.
  3. Mount the pump inside the mounting bracket. If you are not using a mounting bracket, ensure that there is ample space in front of the pump to route the tube that will supply water to the RO system. The pump can sit on the floor of the cabinet or mount to the wall in any direction. Pumps may make more noise depending on the location of the pump and mount.
  4. Cut the tube that runs between the tank and the RO system and insert the pressure switch.
  5. Connect the electrical wires from the pump and transformer to the pressure switch.
  6. Turn the water supply line on. Water should come out of the RO system’s faucet. Ensure there are no leaks in the unit.
  7. Plug in the booster pump. If the pump is working, more water will come out of the faucet.
  8. Turn the valve on the storage tank on. The RO system is now working in conjunction with the booster pump.

Best reverse osmosis booster pumps

SHURflo 8075-132-313 Gold Series

The SHURflo 8075-132-313 Gold Series is a reliable booster pump with a long lifespan and quiet operation. This pump can help an RO system produce filtered water closer to the membrane specifications of the system to the storage tank. Its one-piece solid diaphragm reduces leakage, and its construction makes the motor resistant to corrosion.

Aquatec CDP 8800 Pressure Boost Pump Kit

The Aquatec CDP 8800 Pressure Boost Pump Kit, like the SHURflo 8075, allows your RO system to produce filtered water closer to the membrane specifications. This pump is designed for operation with a tank shut-off switch and can produce outlet pressure of up to 110 psi. It uses a 3-chamber diaphragm pump that has a long lifespan as long as the unit does not exceed 150°F.


If you have any additional questions about reverse osmosis booster pumps, please do not hesitate to contact our experts.


Comments 1-10 of 1

I have a Culligan RO filtration system for a faucet and the ice-maker of a GE refrigerator. It does not appear to produce enough pressure for the ice-maker (40-120 psi). Can I add an inexpensive pump that goes to the refrigerator line that is 120 volts, has a pressure limiting switch, and is on-demand?

Dennis Galbraith on March 27, 2023
Leave a comment