Can You Use a Reverse Osmosis System With a Refrigerator?

By Rehan Iqbal

Reverse osmosis systems filter out more contaminates than any other type of water filter system. This makes your RO system’s tap the source of the best tasting water in your home. Why not take advantage of this purification to get better ice cubes and great tasting chilled water from your refrigerator? Here’s what you need to know about connecting your reverse osmosis system to your refrigerator, including what you’ll need for installation, how to make the connection, and the problems you may come across.

What is Reverse Osmosis, and Why is it Better than a Refrigerator Filter?

Unlike other filters, reverse osmosis uses pressure to trap contaminates in water. This creates clean water, which goes to the tap, and water with concentrated contaminates, which go down the drain. Reverse osmosis filters are usually sold as a system that includes other filters to purify water.

This includes some combination of activated carbon, catalytic carbon, KDF and sediment filters. Some systems also have a remineralization filter. This adds back calcium and magnesium removed by the RO filter, improving the flavor of the water.

Reverse osmosis systems are an effective way to remove lead, chromium, nitrates, arsenic and radium. However, they’re most often used to remove contaminants that are safe to drink, but make the water taste bad.

Since they’re able to filter out a wide range of contaminants, RO systems deliver better tasting, healthier water than you’ll get from the activated carbon filters used in modern refrigerator water dispensers.

Why Should I Connect My Refrigerator to an RO System?

While your refrigerator’s carbon filter is effective at removing chlorine, is doesn’t remove as many contaminates as reverse osmosis systems. You should use RO water if you have contaminates that can only be removed by a reverse osmosis filter, like arsenic and nitrates.

Normally, the water you get out of a tabletop or under sink reverse osmosis system comes out of a small tap. This water is room temperature. You could get cold water by filling a container with water and keep it in the fridge, but it’s easier to send RO water to your refrigerator’s water dispenser. That way, you have cold, clean water whenever you want it.

Using water from your RO system makes better tasting and better looking ice. Since this water doesn’t contain dissolved solids, it keeps the ice from turning cloudy. By using RO water, you can make ice at home that is the same quality as bagged ice.

Do I Need to Do Anything to My Refrigerator to Connect it to an RO System?

It depends on your refrigerator and your plumbing. There are two things that can cause problems: built-in water filters and copper pipes.

If your refrigerator water dispenser already has a filtration system, it may not work when connected to an RO system. Water needs to be pressurized to push through the refrigerator’s carbon filter. Normally, that’s not a problem with regular tap water connections.

However, the resistance from the reverse osmosis filter reduces water pressure by 50% or more. At that point, water has trouble passing through the refrigerator’s filter. This slows down the flow rate of your refrigerator’s water dispenser to a trickle. It also keeps the ice maker from filling the tray, resulting in small or hollow ice cubes.

In turn, this can jam up the dispenser, or create frost buildup inside the ice maker. However, most refrigerator manufacturers offer a bypass plug or bypass filter that lets you remove the carbon filter. That way, RO water goes directly to your refrigerator’s ice maker and water dispenser.

The designs of these adapters vary widely from model to model, so you’ll need to do some hunting to find the right one for your appliance. Some refrigerators automatically bypass the filter system when the filter is removed.

Copper line cannot be used with RO water. Reverse osmosis removes dissolved solids. Water with low Total Dissolved Solids (TDS) will pick up minerals from anything it comes in contact with, including copper lines.

This adds copper to the water, and will dissolve the pipe, resulting in pinhole leaks. You can only use polyethylene line between your RO system and your refrigerator. Fortunately, most refrigerator connection kits include the hose you need for a safe connection.

How Do I Connect My Refrigerator to My RO System?

Most companies that make RO systems offer kits to connect a refrigerator to the system. This adds a T connector to the hose between the final stage of the filtering system and the faucet, along with a piece of water hose and a shutoff valve. With most installations, you only need to run a few feet of hose to go between your kitchen sink and your refrigerator.
However, friction from the inside surface of the hose can lower water flow rates enough to cause problems for long runs. If you need a line more than 30 feet long, you may need to use a larger diameter hose than you get with the kit.
If your refrigerator is already connected to a water line, you need to disconnect it and cap the connection. Trace the connection back to a shut off valve. Close the valve, then use the drinking water faucet on the refrigerator to purge the system.
Remove the water line between the refrigerator and the valve, and install a cap over the connector. Some installation kits include a cap, but if it doesn’t have one, you can pick one up at any hardware store. Once this cap is in place, you can open the valve again, restoring the water supply to other connections.
Next, shut off the water supply to the RO system. If you have a booster pump, make sure it’s off. Use the faucet to release any remaining pressure in the system. You’ll want to put down a bucket or bowl below the filtered water line to catch any drips.
Cut this line and connect both ends to the T connector. Attach a few inches of hose to the open port, followed by the shutoff valve. This lets you shut off the water supply to the refrigerator, in case you need to work on it. Run a length of hose from the shutoff valve to the refrigerator.
Once everything’s connected, flush system according to the refrigerator’s instructions.

I Only Want to Run RO Water to My Refrigerator - Do I Need to Do Anything Differently?

You can run a hose directly from the RO system to the refrigerator, as long as you add a shutoff valve. However, you may have trouble with loose carbon clogging the refrigerator’s water lines.

This carbon comes from new activated and catalytic carbon filters in your RO system. When you first install the system, and each time you change the cartridges, you need to purge the line. Once the water runs clear, you can reconnect the line to your refrigerator.

Solving Pressure-Related Issues

Most problems people have with using RO water with their refrigerator have to do with pressure. Even with a filter bypass, low pressure water can take ages to fill your glass. It also causes issues with ice makers, forming frost or creating small, hollow ice cubes.

If your RO system has a storage tank, this problem may be intermittent. When the refrigerator first draws water from the tank, there’s plenty of pressure. However, that pressure drops when the tank is nearly empty, causing flow issues. There are two ways around this.

Installing a second storage tank or a larger tank may keep the refrigerator supplied with enough high pressure water to cycle through an ice making cycle. Alternatively, you can add a booster pump to increase pressure. This pump switches on when the water pressure gets too low, maintaining the supply of water to the refrigerator water dispenser.