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Reverse Osmosis vs Distilled Water: What’s The Difference?

Scott Winfield
Written by Scott Winfield
Last Updated on

Not many people know the difference between distilled and reverse osmosis water, or even if there is a difference in the first place.

But there is, and it mainly boils down to how these two types of water are filtered. Let’s explain so you have an easier time picking the kind you need.

Differences Between Reverse Osmosis Water and Distilled Water

The main difference between reverse osmosis and distilled water is the filtration process. Reverse osmosis filters water through a semi-permeable membrane, while distillation uses heat to turn water into vapor, which is then collected and allowed to cool.

Reverse osmosis is a filtration process that pushes water through a semi-permeable membrane. The membrane, also known as the screen, has microscopic holes that allow only small particles to pass through. This means that the small hydrogen and oxygen molecules of water can easily pass through the screen, while the larger molecules found in many common water contaminants are caught by the membrane.

Distillation, on the other hand, is a much simpler but very effective filtration process that involves boiling the water. The heat turns the water into vapor, which is then condensed in the upper part of the distillation unit and transferred into a clean water container. As the debris and contaminants are heavier than water particles, they’re left at the bottom of the heating element.

Both purification methods are effective, but they each have their pros and cons.

RO Water vs Distilled Water Comparison Table

Distilled WaterReverse Osmosis Water
Filtration methodBoilingThe water passes through a semipermeable membrane
Filtration processSingle stageSingle or multi-stage
Filtration capacity~0.3 gallons per hour~3 gallons per hour
Contaminants removedComplete removal: algae, arsenic, bacteria, chlorine, copper, fluoride, lead, mercury, nitrates, pathogens, pesticides, rust, salt, sulfates, virusesComplete removal: chlorine, lead, mercury, pesticides, rust   Partial removal: algae, arsenic, bacteria, copper, fluoride, nitrates, salt

What is RO Water?

Reverse osmosis water is any water filtered through a reverse osmosis system. And, thanks to the reverse osmosis filtration method, RO water is considered one of the purest in terms of pollutants and contaminants – although this also depends on the size of the micron filter.

Benefits & Drawbacks of Drinking RO Water

The biggest benefit to drinking reverse osmosis water is that the RO process removes a large number of potential contaminants like chlorine, chloramine, bacteria, and so on, which makes the water a lot safer to drink. The better the filter, the more contaminants are removed.

Reverse osmosis can be a single or several-stage filtration process. Smaller units usually have one large micron sediment filter to remove only large soil particles from your drinking water.

Multi-membrane units, on the other hand, can remove pretty much anything from your water supply, including beneficial minerals – but these units come at a higher price.

Single-stage RO units will cost you several hundred dollars, while multi-stage units can set you back several thousand. There are a lot of different RO System models to pick from, so the exact price will depend on the brand and the unit size, but in any case, RO water systems are far more expensive than distillers.

On the other hand, reverse osmosis systems can be integrated much more seamlessly into your home’s water system. You can simply attach these filters and get immediate access to RO water straight from your tap.

Therefore, if budget is not a problem for you, multi-membrane RO units beat distillers in convenience and efficiency.

What is Distilled Water?

Distilled water is a type of water that’s been purified through the distillation method. Distillation refers to boiling the water past the point where it becomes steam and then cooling it to liquid form again. All in all, it’s an incredibly effective process of removing minerals and contaminants from water.

Distilled Water
Distilled Water

However, while distilling gets rid of most viruses and germs, you do need to pay attention to the quality of the distillation process that you use. During the distillation process, any chlorine in the water will turn to a volatile gas that could still make its way through the steam to the final product if a distillation machine doesn’t properly address that. Let’s explore the benefits and drawbacks of drinking distilled water compared to RO water.

Benefits & Drawbacks of Drinking Distilled Water

Similar to reverse osmosis water, the biggest benefit to drinking distilled water is that a lot of viruses, bacteria, chlorine, and other potential contaminants are removed so the water is cleaner and safer to drink.

Distillers are usually priced below $100. This makes them significantly more affordable than most reverse osmosis systems since even the cheaper models cost at least several hundred dollars.

This more affordable pricing makes distillers a much better option for people who want to start drinking purified water but are still unsure if they want to invest in large whole-house filtration units.

However, this comes at a price; you’ll need to manually fill the distiller and wait for the lengthy distillation process to finish before you’re able to drink a glass of water. This is fine if you live in an area with mostly clean water, but if you can’t drink the water from your faucet without filtering it, then waiting close to an hour for the distillation process to give you a third of a gallon of water isn’t practical in the long run.

Also, be careful with inexpensive units that may not properly deal with chlorine gas during the distillation process and the possibility of not effectively filtering out the chlorine in your water.

Is Reverse Osmosis Water Better than Distilled Water?

Reverse osmosis and distilled water have different strengths and weaknesses. Reverse osmosis removes chemicals faster and more efficiently than distillation but eliminates fewer contaminants.

Both methods remove minerals from the water, but reverse osmosis systems are significantly less effective at removing hard minerals since they clog the filters quicker than other types of contaminants.

The final decision on whether you should drink reverse osmosis or distilled water will depend on what you’re trying to eliminate from your water and how much you’re willing to invest in a unit.

If you want to remove hard minerals from your water, then distilling is the better option. However, while both distilling and RO remove bacteria, viruses, and many other contaminants from your water, reverse osmosis is a quicker process, although it doesn’t remove some contaminants like algae, arsenic, bacteria, copper, fluoride, nitrates, and salt, as effectively as distillation.

Additionally, while distilling is better at removing hard minerals from water, you’ll have a much harder time remineralizing distilled water and adding healthy minerals back into it. Reverse osmosis, on the other hand, is more compatible with remineralization filters, so it makes the process much more seamless.


In conclusion, reverse osmosis is a bit pricey but automatically filters the water for you. Distillation is cheaper but requires a lot of manual effort, and the filtration process takes a lot more time. That being said, with distillation, you’ll be removing more contaminants from your water.

We recommend that you carefully consider these things and choose whichever method suits your needs and preferences better.

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Scott Winfield
Scott Winfield
My name is Scott Winfield and researching and writing about water filters and other strategies to purify water has become my full time passion in recent years. I'm glad that you found our site and you can look forward to authoritative and well researched content here to help you get the best in water.
  1. I agree with most of what you say. Just a couple of small points: A distiller can remove chlorine, provided you maintain a post-distillate carbon filter in the unit. And you don’t have to wait for an hour to produce distilled water to drink – you simply implement a procedure where you stay ahead of your needs with another, previously distilled amount, so you always have water at the ready.

  2. I’m confused. Your table shows distilled water as capable of removing chlorine as well as in part of your story but then later in the story, you contradict this statement and say it does not filter chlorine. So which is it?

    1. Hi John, thank you for reading and also for your feedback. We needed to go into more detail there to explain the apparent contradiction. The article has now been updated in a couple of spots to explain how chlorine gas needs to be addressed in the distillation process. If not properly addressed, indeed, this is a drawback to distillation.

  3. Thank you for the article and the thorough explanation, it was very informative. I’ve been buying distilled water for my house plants, but we recently purchased a RO under sink system. I believe the plants will be just fine with the water from the filter system. Thanking You Again.

  4. I think distilled is superior for removing contaminants such as dissolved drugs and stuff in the water. I wonder about the things that are volatile and make it though.

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