Reverse Osmosis vs Distilled Water: The 2021 Definitive Comparison

Reverse Osmosis vs Distilled Water

In the world of water purification, there are certain products that are pretty good at removing specific contaminants – and then there are the godlike products that can handle anything.

Reverse osmosis and distillation are undoubtedly the two most effective water treatment options. Both provide an alternative to drinking water from a bottle, and can remove more than 99.9% of all total dissolved solids (TDS) from water, which is a big deal – it means your city or well water will end up about as pure as it could ever be on earth.

Looking at water composition alone, both of these systems clearly have a lot going for them. But when it comes to reverse osmosis vs distilled water, what are the differences worth knowing about? If both water treatment options essentially produce the same results, is there any reason why you might choose one over the other? I’ll be covering all the details you need in this guide.

Is Reverse Osmosis Water The Same As Distilled Water?

At first examination, reverse osmosis water and distilled water are pretty much classed as the same thing: pure, or purified water. Both water distillation systems and reverse osmosis units can purify water by removing a broad range of contaminants, including volatile organic compounds, heavy metals, and chlorine.

However, there are certain contaminants that, due to their design, reverse osmosis systems or distillers may not be able to fully remove. This may mean that, while the water produced from both systems is still essentially pure, there are small differences that are worth noting.

Reverse osmosis, for instance, is not as effective against agricultural treatment chemicals, such as pesticides, herbicides and fungicides. It may also struggle to fully eliminate some dissolved gases and organic compounds.

Distillation, on the other hand, isn’t the best solution for removing certain chemicals, metals and particles with high vapor pressure, such as mercury, which may be capable of evaporating and condensing with water during the distillation process. Again, this is on such a low level that these contaminants won’t be left behind at dangerous levels with either treatment option.

Another thing to consider is that many modern reverse osmosis systems involve a remineralization filter, which enables you to get access to human-healthy minerals in the water that were removed during the filtration process. In this case, reverse osmosis water is considered more alkaline (and often better tasting; not so flat, as a result) than distilled water.

What is Reverse Osmosis?

Reverse osmosis is a purification process that will force water through a multiple-stage filtration system at a high pressure. A reverse osmosis water filtration system usually involves a pre-filter, an activated carbon filter, a reverse osmosis membrane and a post-filter.

The RO membrane contains pores that are so tiny that only water molecules, when forced by a high pressure, can pass through from one side to another, while impurities, which are too large, must remain behind. This enables RO to offer some of the best impurity-free water benefits on offer from at-home filtration processes.

reverse osmosis filter

Advantages

Immediate clean water access

One of the better features of a reverse osmosis system is that it’s typically installed directly at your water line, which allows you to get immediate access to clean tap water with this type of purified water solution. If you’re looking for the simplest purification solution that will remove impurities without disrupting how you currently access your drinking water, reverse osmosis filtration systems are a great option.

Optional remineralization cartridges

Most reverse osmosis units now come with an optional remineralization cartridge for re-adding different minerals such as calcium and magnesium that the system naturally eliminates in your tap water supply. This is a huge benefit if you enjoy the taste of mineral-rich drinking water or you want to ensure you can reap the benefits of healthy minerals from your liquids.

Because these cartridges are available to use with the reverse osmosis system, they’re designed to fit nicely in with the rest of the components of the unit.

reverse osmosis system for home

Disadvantages

Requires more frequent maintenance/ service

First off, the reverse osmosis process might be as effective at removing common tap water impurities as distillation, but you’ll need to spend more money to service a reverse osmosis system if you want to maintain a high quality of water purification.

The different water filters and semi-permeable membrane require replacing once they become too saturated with impurities from your water supply (once every 6-12 months for the carbon/ pre-filters and once every two years for the membrane is common).

More expensive

The average under-sink water reverse osmosis unit costs around $300. You can pay less than that, but take note that generally, price reflects quality. You’re going to want to spend a lot of money on a reverse osmosis water filter if you’re after the best performing system that ensures pure water that’s free of the most contaminants – and that includes money spent on the replacement membrane and filters.

What is Distillation?

The second most beneficial type of water purification, water distillation, is the simple process of boiling water to remove a wide range of contaminants.

The majority of contaminants don’t have the same boiling point as water, which means that once water begins to boil and evaporates into steam during the distillation process, impurities such as lead, bacteria, viruses, sediment and arsenic are unable to take on a gaseous form, and are left behind in the boiling chamber.

In most water distillers, this evaporated water will then travel through a corridor before condensing (turning back into a liquid) into a clean container.

how water distillers work

Advantages

Doesn’t need connecting to a water line

Distillers are one of the few water systems that don’t require connecting up to your main water pipe. Not only does this mean you can save the effort of cutting into your pipes; the lack of installation also helps to keep the cost down, making distilled water solutions cheaper in general than the RO process.

Distillation also provides an on-the-go drinking water solution, making it easy for you to drink water that’s free of impurities like dissolved solids, chemicals such as chlorine, bacteria, salts, metals like lead, and other impurities that could affect your health, whether you’re at home, work, or staying at a vacation property.

You just need access to electricity for the system to function – and you will have to fill the machine with water on a regular basis, usually several times per day.

Less frequent maintenance

You can distill as many batches of distilled water as you want in a water distillation unit without having to worry about changing any membrane or filtering cartridges. Distillation is a simple scientific process that doesn’t need much to result in purified water – just heat and a suitable tank for boiling, holding the steam, and collecting the contaminant-free water at the end.

The only thing you’ll need to replace in this type of water purification unit is the carbon filtration cartridge at the spout – though not everyone even bothers to use this cartridge, as it doesn’t make much of a difference after the water distilled process.

Waterwise 4000 Water Distiller review

Disadvantages

Take a long time to get distilled water

It’s common for water distillation units to take up to 4 hours to produce a single 1-gallon batch of distilled water.

You’re talking hours and hours if you’re looking to make a big batch of multiple gallons of water, and you’ll probably have to refill the system with fresh water multiple times, too. This is a pretty obvious disadvantage if it’s essential to you that a filtered water system produces clean drinking water immediately.

The distillation method involves processes that are incredibly slow and not very efficient; even slower than gravity filtered water methods, as water must boil, evaporate into steam, and then condense into liquid state, drop by drop, into a container.

It also requires a relatively high amount of energy to operate. Distillation does tend to offer the most highly effective result compared with different methods like gravity filtration, however, and having super-purified water may mean that the wait is worth it for you.

No easy remineralization solution

Another of the cons of a distillation system is that if you want to reintroduce essential minerals to your water, the methods available aren’t quite as easy as they are with reverse osmosis.

While many RO units come with mineral filters, or offer an easier option to effectively install mineral filters at your main water line, distillation machines don’t have the option for this form of remineralization.

The easiest solution, if you don’t want treated water that tastes completely flat, would be to add a safe amount of naturally occurring minerals back into a batch of distilled water with mineral drops, which you can buy online.

Related: Is Distilled Water Safe to Drink? My Complete Guide

Reverse Osmosis Vs. Distilled Water: Which is Better?

Comparing reverse osmosis vs distilled water, the biggest difference between the two comes down to the systems that produce them. Because reverse osmosis water and distilled water essentially look the same – and taste the same, for that matter – your decision will most likely come down to which purified water solution you prefer.

A distiller, for instance, tends to have a lower price point than reverse osmosis systems. But these units take up to 4 hours to produce a single batch of distilled water, which definitely makes them the less convenient option, especially if you’re looking for a clean water option for your whole family.

Reverse osmosis systems, on the other hand, can cost up to double the price of distilled water machines, but they offer immediate access to drinking water directly from your faucet – and many of them improve the taste and composition of water with an included remineralization filter, too.

In terms of your health, the reverse osmosis and distillation water purification method are both excellent. Drinking distilled water or reverse osmosis water will eliminate the need for bottled water, as you’ll have access to a clean, safe drinking water supply in your own home.

Both systems give you a lower level of control over which impurities are filtered out of water – so the bad, the good, and the necessary are all removed.

However, keep in mind that getting a high number of natural minerals from water isn’t important, and you can find more than enough of the likes of calcium, magnesium and healthy salts like sodium in much higher quantities in your food than in any water source you’ll drink at home.

Your body will benefit much more from minerals found in fruits and veggies, so be sure your diet is right if you’re concerned that cutting minerals out of your drinking water will really make a difference.

Minerals aside, both RO membranes and distillation are designed to remove almost exactly the same range of impurities across a broad spectrum, including volatile organic compounds (VOCs), iron, chemical substances, fluoride, copper, natural elements, and microorganisms.

Either process can provide an incredibly thorough contaminant removal and clean water production that you’ll struggle to achieve without RO membranes or distillation.