Distilled vs. Deionized Water: Differences Explained

When it comes to water and how it’s used, its cleanliness is a very important factor that needs to be taken into consideration. Many people drink tap water without any health problems, but when it comes to the plumbing systems in your building, deionized water specifically is needed. But what is deionized water and how is it different from the tap water that your home gets?

Understandably, many home or business owners don’t know what deionized water is and often consider it to be a different kind of distilled water. That isn’t correct, though, and the two types of water have many differences. We’ve explained some of their differences in this article and how they might be used today, even in your home!

If you want to learn more about deionized water or if you want to get a water purification system installed in Phoenix or one of the surrounding areas, you can contact our team at Diamondback Plumbing today.

What Is Distilled Water and How Is It Made?

If you’ve ever bought a bottle of water or poured water from a filter jug for your home, there’s a high chance that you know exactly what distilled water is. Distilled water, as the name suggests, is any water that’s been purified of any contaminants via distillation. Typically, the water used for this process is spring water, but your regular water supply can be used too. In some cases, a home can even have a distiller installed!

The distillation process is quite simple; to remove the contaminants (salt and lingering particles) from the water, the water is heated and boiled through heat exchangers or in a tank. As it boils, the steam collects and gets condensed in a nearby container to create clean distilled water that’s perfect for drinking.

What Is Deionized Water and How Is It Made?

Deionized water, while still being water at its chemical core, is far different from the water you get in store-bought water bottles. While both are similar in the fact that their processes remove ion-based and other natural impurities from your water supply, that’s where the similarities end. 

The answer to the question of “is deionized water the same as distilled water?” comes down to the purification process. Deionized water is made by running water – tap, spring, or even distilled water – through a special type of resin. This particular resin has a certain level of an electric charge to it, though often with both a positive and a negative charge. 

When the water passes through it, any positive and negative charged ions in the water are exchanged with the positive charged hydrogen and negative charged hydroxide ions in the resin. The result you get through the process is H2O or simple water. However, this water is considered highly reactive and becomes far more acidic the moment it comes into contact with the air. 

What is the Key Difference Between Deionized and Distilled Water?

Beyond just the differences in the purification processes for both distilled and deionized water, their purity is also a key difference. Since distilled water can be made from the tap or spring water, this type is often far cleaner. The boiling process not only removes any minerals and contaminants from the water itself but also gets rid of most – if not all – of the viruses and bacteria in it. 

The purity of deionized water, on the other hand, depends on what the initial type of water was. The process used to remove most of the ions in water doesn’t actually get rid of most of the contaminants since many of them don’t have any positive or negative electric charges. This often means that any organic particles like bacteria or “molecular species” like sugar remain in the deionized water.

A comparison of distilled vs deionized water using spring water will more than likely reveal that the distilled water has very low amounts of bacteria, viruses, or minerals in it. The deionized water will likely be the opposite, in addition to being more corrosive. That’s why it’s incredibly likely that the deionized water that’s used in cases like plumbing was originally distilled water instead!

Common Uses for Deionized Water

Another great way to understand the answer to “what is deionized water?” is by looking at its various uses. As we mentioned earlier, there are a few plumbing systems that do use deionized water, but it also has many more uses outside of plumbing. However, it’s important to note that, due to its highly reactive form, deionized water is never used for drinking or cooking food unless its base was distilled water – which eventually can become distilled again over time.

Reverse Osmosis Water Filters

In the plumbing industry, water is a simple yet important part of your home. Of course, plumbing has everything to do with water. Everything from the first step of bringing the supply to your home to the final step of getting it to your public drain system for treatment is all done by the pipes. However, very few people know that their home’s water filter uses deionized water. 

Reverse osmosis water filters specifically use deionized water to remove any dissolved salts and oxygen from the water supply. Since the salt and oxygen molecules have specific electrical charges, the deionized water can attract and neutralize them before the water supply is distributed to the taps, much like water softeners.

Cooling Water Heaters and Other Home Systems

Deionized water is also often used for cooling down many of your home’s systems and appliances, like water heaters and even furnaces. When normal tap water is used, the minerals like calcium and salt can gather and collect in the pipes and other elements, hardening when it dries out. The deionized water doesn’t contain these minerals, effectively reducing the chance of mineral-related clogs forming. 


Distilled and deionized water each have its unique differences that make them great for different purposes. Due to its purity, distilled water is ideal for cooking and drinking, often even best used for making other kinds of water. Deionized water, while great for cleaning appliances and filtering, is frequently used in labs as a part of chemical solutions. 

Despite this though, both can be used around the house and even have their systems for home and business needs. If you’re interested in looking for such systems, you can contact our team at Diamondback Plumbing today!

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