Reverse Osmosis Vs. Deionized Water: What’s the Difference?

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If concerned about the quality of water in your home, chances are you are thinking of getting a water filtration system. These units purify water and ensure that it’s safe for your family and loved ones to drink, cook and wash with.

And although there are numerous types of water filtration systems today, none can match the functionality of reverse osmosis and deionized water systems.

The 2 systems can get you the purest drinking, cooking, bathing, and washing water possible. In addition, they are excellent at removing contaminants and minerals from your water.

However, like any other system, each water purification system has its pros and cons. They differ from each other.

The major difference between the two systems is that while RO uses a semipermeable membrane to filter water, deionization uses ion exchange to replace contaminants and minerals with hydrogen and hydroxyl.

In this article, we’ll go through how the 2 systems work as well as their pros and cons. We will also find out the clear winner between the 2.

What is Reverse Osmosis and RO Water?

RO is a water filtration process that removes bacteria and impurities from the water. It can filter most known water impurities, including organic chemicals, lead, chlorine, silicates, pesticides, herbicides, arsenic, asbestos, radionuclides, and cysts.

RO water is, therefore, the water you get after a successful RO filtration process.  It is pure water that is free of contaminants and chemicals, hence safe for cooking, drinking and washing.

How Do RO Systems Work?

Reverse osmosis involves several filtration stages, the first stage being the pre-cleaning process. Here, a pre-filter removes sediments such as rust and dirt.

Some systems use a carbon filter that helps to reduce VOCs (Volatile organic compounds) including chlorine and other contaminants that give your water a bad taste or odor.

To ensure that you get pure RO water, carbon filters appear again at the end of the purification process.

Water is then placed under high pressure, which forces it through an RO membrane. The membrane is a thick polyamide film with small poles that block organic particles but are large enough to allow the water to pass through.

The filtered water is stored in a tank until when needed. When the storage tank gets full, the system shuts off automatically and restarts when more water is needed in the tank.

What is Deionization and Deionization Water?

Deionization is a water treatment process that removes mineral salt contaminants. The process removes cations such as sodium ions, calcium, copper, and anions such as chloride and bromide out of the water.

The system uses tanks full of ion exchange resin to purify contaminated water. This resin binds with any mineral salts in the water and separates them, allowing only clean water to leave the tank.

So, what is deionized water?

Deionized water, also known as demineralized water, is water wherein all minerals like calcium, magnesium, sodium, iron, copper, and sulfates are removed. Thus, it is free of any toxins and chemicals.

Actually, deionization can produce 3 grades of purified water, including high-purity water, demineralized water, and lab grade/medical grade water.

How Do Deionization Systems Work?

An ion exchange system with tiny resin beads attracts and retains all electrically charged mineral particles; water passes through these beads, these particles bind to the resin beads, and the cleaned water(deionized) passes to a storage tank.

Deionized water is often confused with distilled water, although not the same. Distilled water is obtained through steaming and boiling, and although it’s a purer form of water, it can’t compare to deionized water.

Benefits and Downsides of Reverse Osmosis and Deionized Water.

Benefits of RO Water

1. Makes you stop buying bottled water

If you hate the taste of your tap water or are concerned about what it might contain, there’s a good chance that you’ll think of purchasing bottled water.

Bottled water is expensive, and plastic bottles also create a lot of waste as they often end up in landfills. In addition, bottled water isn’t as pure as you might think. It’s just filtered tap water.

RO water is a cheaper alternative and gives you access to pure drinking water right from your water tap.

2. It’s better for cooking

Do you know that impurities in your water can affect the taste of your food? Think about it. Where does the water that you use to cook your meals end up? In the food, right?

When you prepare soups, boil pasta or make homemade bread, pure water makes a lot of difference.

If using municipal tap water for cooking, chances are, there’s too much chlorine in it. The chlorine will not only give your food an odd taste but also discolor it,

You’ll also find that tea and coffee taste much better when prepared using RO water. And did you know that most high-end restaurants now use RO water for cooking? That’s just how effective it is.

3. RO water tastes delicious

Perhaps the main reason why you should have RO water in your home at all times is because of how tasty the water is. After removing all the impurities, what’s left is clean, pure, and refreshing water.

One important thing to note is that RO systems filter your water through 3 carbon filters before you can get it from the tap. The last carbon filter acts as a polishing filter to remove any lingering taste or odor.

Actually, most families that use RO water find themselves taking more water and less sugary drinks like soda and juice.

4. Makes crystal clear ice cubes

Have you ever tried to make ice cubes but got white and cloudy ones? Well, this is because of gasses and impurities in your water, which crystalize as the water freezes.

If you enjoy preparing eye-catching cocktails, you’ll agree that crystal clear ice cubes look fantastic in the drinks. And there’s more! Cloudy ice cubes tend to be softer and melt faster than clear ice cubes.

It, therefore, means that using ice cubes made with RO water keeps drinks cool longer.

Disadvantages of RO Water

RO water lacks essential minerals

Reverse osmosis filters out essential minerals such as calcium and magnesium, which are valuable to your health. Unfortunately, this means that you will have to look for mineral supplements to replace the lost minerals.

Benefits of Deionized Water

1. The water of choice for manufacturing and factory settings

Most manufacturing firms and factories use deionized water to avoid the buildup of salts on machinery. This water can also be used to cool and lubricate machines in any industrial setting.

It can also be used in the manufacture of cosmetics, medicine and to process foods as well.

2. It can be used for detox.

Some health experts recommend using deionized water for detox. This should, however, be for short-term use only.

If you choose to detox this way, ensure that you consult a health expert.

Disadvantages of Deionized Water

1. Tastes bland

Since this water is free of ions and minerals, it has a bland taste. Your taste buds might find it really hard to cope with. This might lead you to seek alternatives like soda and other sugary drinks, which might harm your health.

2. Risk of toxic metals

If you usually get your deionized water from the tap, you are highly likely to consume water with toxic metals.

Deionized water is a less stable form of water and, therefore, more susceptible to attracting metals in the plumbs.

Which Water is the Best for Your Family? RO or Deionized?

Both systems (RO and Deionization) work great, as evidenced by the benefits they offer. Deionization removes contaminants and softens the water, while reverse osmosis gives you the purest form of water.

A combined RO system and deionization offer you the best for your family. But if you have to go with one only, the best choice is reverse osmosis.

RO water is free of contaminants. It filters viruses and bacteria as well, which never happens with deionization.

Deionization filters also require more maintenance since you have to change them regularly.


When choosing the best water for your family, you need to consider what you will use the water for. For example, RO water is excellent for cooking and drinking, while deionized water is superb for cleaning. Choose the best water filtration system, and you’ll always have a constant supply of the water you want for your home.