Do RO (reverse osmosis) systems remove sodium?

Do reverse osmosis purification systems remove sodium or salt particles from your drinking water?

Before answering this question, it's important to note that there are different types of RO systems and different levels of purification. You can read up on some of the best water purifiers here for more info.

But for the purposes of answering our question, let's look at the most typical stages of filtration for an RO system. They can include any of the following:

  • Sediment filtration
  • Granular carbon and carbon block
  • Reverse osmosis membrane
  • Post carbon
  • Ultraviolet light 

We'll look at the simple answer to our question, then talk about where sodium removal can occur in a typical RO system.

Do RO systems remove sodium? The Simple Answer

In most cases, RO systems will remove salt particles and sodium from your drinking water, though it depends on the number of filtration stages and the types of filtration present.

Physical Salt Particles

The easiest type of salt for an RO purifier to get rid of is physical salt particles. These are usually large enough to be picked up and removed by the sediment filter, the most basic stage of filtration and usually the first stop for water coming into an RO system.

Dissolved Sodium

Dissolved sodium, which isn't visible in water but can impact the taste, requires a more intense level of filtration. The best bet for removing sodium is going to be a high rejection RO membrane, which can also remove things like fluoride, lead, and other metal elements. 

Here's what it looks like in an RO system diagram:

High Rejection RO Membrane

The high rejection RO membrane is likely to remove most sodium from your drinking water and is the blue tube in this particular diagram.

Any filtration system labeled RO or reverse osmosis should have this stage of purification included. It's going to be placed after the sediment and carbon filters because those deal with larger contaminants that shouldn't be passing through the RO membrane.

In addition to sodium, this stage of filtration can also remove common viruses, which the CDC describes here.

Read more: Best water purifier for viruses

Is sodium in my drinking water harmful?

Sodium is just one of many contaminants that an RO system can deal with. But is sodium in your drinking water particularly harmful?

In most cases, it's not going to be harmful.

At worst, it might be a bit unpleasant or contribute to a poor taste or just a less "pure tasting" water from your tap.

Are certain RO systems better at removing sodium?

The quality of filtration you get from your RO system will depend on the number of stages. As you add stages, the quality of the final product improves.

But when it comes to sodium specifically, as long as your RO system has the reverse osmosis membrane stage - which all of them should - there isn't going to be one that's better for sodium, as they should all be equally effective.


To summarize:

RO systems can definitely remove sodium from your drinking water. The more filtration stages an RO system has, the more effective it will be. However, the high rejection reverse osmosis membrane is the one you want to keep an eye on.

For those buying a new purification system, make sure that membrane is included.

If you have additional questions about RO systems and getting sodium out of your drinking water, feel free to drop me a line in the comments section below and I'll help out as best I can.

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6 thoughts on “Do RO (reverse osmosis) systems remove sodium?

  • I am installing a salt based water softener and was looking at installing a tankless RO system under sink for drinking and cooking water…. my concern was the slight excess salt as well. Any difference between a tankless versus traditional RO system?

    • I’m not as familiar with the tankless options, but I’d imagine they work similarly. I’d bet the tankless costs less to run.

  • I have heard that RO systems get plugged with calcium and magnesium, but not with sodium. Some, who sell both softeners and RO systems, say that water should be softened before feeding an RO system. Since a softener removes calcium and magnesium, but replaces these elements with twice the number of sodium atoms, it seems that soft water would be twice as likely to plug than hard water.

  • I just bought a MAXBLUE RO system (not yet installed) it only has a NSF 42 rating. will this system remove sodium (i have a softner). My research says that All Reverse Osmosis systems will remove sodium, is this true? I’m concerned of the low rating.

  • Greeting,

    Is there easier and much convenient process of removing salt or sodium from the water,

    Thank you for your information,

    • I would think even a more generic pitcher filter would get most of the salt out. Dissolved salt probably needs the RO system.

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