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What is Demineralized Water?


*Reviewed by Ken Christopher, Senior Vice President at Rayne Dealership Corporation

Are you curious about demineralized water but aren’t sure if it’s right for you? Demineralized water is simply water that has had most of its mineral content removed. While demineralized water is necessary in certain industrial and commercial applications, most of the tap water entering your home contains dissolved minerals. 

Before choosing to remove the minerals in the water, you should understand what those minerals are, how they are removed, and what the impact of the removal process is. In a residential setting, the most effective method of creating demineralized water is through the use of a reverse osmosis filtration system. Not only does reverse osmosis remove the minerals and salts from water, but it also removes a wide array of other contaminants from your water.

What is Demineralized Water?

Not sure what is demineralized water? You may not realize most of the water you drink has some mineral content in it. Those minerals and salts are picked up by water as it percolates through the ground and soil.

The mineral content of the water is determined by the types of soil it moves through. If the ground is rich in limestone, your water will contain higher levels of calcium carbonate. Your water will also pick up salts and metals in addition to minerals. These minerals, salts, and metals collectively are referred to as the total dissolved solids (TDS) in water.

Demineralized water has had most, if not all, of these essential minerals, salts, and metals removed from it. This alters the water in important ways.

Effects of Demineralizing Water

The mineral content in water can damage equipment in industrial settings, alter the PH of soil in agricultural settings, or alter the final product in pharmaceutical production. Demineralized water offers a more neutral starting point for the production of medicines, gives agricultural growers greater control over their crops, and protects industrial equipment and boilers from damaging salts and minerals.

In a residential setting, the mineral content of water can shorten the lifespan of your water heater, dishwasher, or coffee pot. You’ll also see the mineral content of water left as whitish-gray deposits on surfaces that come into contact with water, such as in your bathroom or kitchen. These mineral deposits are known as scaling.

The mineral content in hard water leads to the formation of soap scum, which occurs when the minerals in hard water react with soap to create a stubborn film. Showering in hard water you’ll notice your soap doesn’t produce a satisfying lather, and it will be more difficult to wash the soap out of your hair or off your skin. Hair and clothes become more brittle when washed in hard water because of this mineral content.

When the mineral content of water is removed the taste is altered as well. This tends to be one of the most controversial aspects of demineralized water or soft water. Though you may not have ever thought about how your water tastes, several key factors affect the taste of water. The mineral content of the water, the presence of any disinfectants used in water treatment, and the presence of volatile organic compounds or gases can all alter the taste of water in important ways.

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How is Water Demineralized?

If you are wondering “what is demineralized water how is it obtained?”, the answer is demineralized water has had its mineral content removed. The most common methods for creating demineralized water are distillation, reverse osmosis, and deionization. Distillation and deionization are typically only used in industrial or commercial settings, while reverse osmosis is used in commercial and residential environments.


The process of distillation is thousands of years old and has served as an important water purification technique to remove impurities over time. Water is distilled by bringing it to a boil. Once the water is boiling the steam produced is captured, condensed, and collected in a separate container. This process is completed using a piece of equipment known as a still.

By changing water from a liquid to a gas and back to a liquid, the dissolved minerals, salts, and are removed from the final product. Distillation will also render microbes, such as protozoa and bacteria, inert through the heating process. Distillation can remove heavy metals such as lead, disinfectants like chlorine, chloramines, and large organic compounds.

While distillation does create highly purified and demineralized water, it simply isn’t practical for residential use. Not only does distillation require a specialized piece of equipment which takes up space, distillation also isn’t ideal for providing water on-demand. The operation of home distillation units can be cost-prohibitive as the electricity cost of bringing large amounts of water to a boil tends to make it more expensive than alternatives like reverse osmosis.

Distillation also won’t remove all of the contaminants found in tap water. Most notably among these are volatile organic compounds (VOCs), such as benzene and toluene. These VOCs boil before or alongside water, passing into the steam and condensing back into the final product. Because of this, the removal of VOCs in distilled water must be done before or after distillation, such as through the use of an activated carbon filter.


Deionization is a complicated process of water demineralization used primarily in industrial and commercial applications for the production of large amounts of demineralized water.

Deionization involves running water through two specialized resins with different charges. One of these is known as a cation resin, which is negatively charged, and one of which is known as an anion resin and is positively charged. These resins act as exchangers– the cation exchanger and anion exchanger facilitate the ion exchange that removes minerals from water to produce clean, safe drinking water. The name of the resin refers to the types of mineral and salt ions it will attract, not its own charge.

Deionizers come in two configurations. Dual-bed deionizers have the two resins in different tanks, while mixed-bed deionizers combine the two resins in the same tank.

As the water passes through the deionization tanks, ion exchange takes place and the ions of the dissolved mineral salts in the water are attracted to the specialized resins. Sometimes this process is completed multiple times until the deionized water reaches required purity levels.

While deionization is highly effective at removing the mineral content from water, it isn’t effective at removing other types of contaminants. Deionization won’t remove microbes such as viruses, bacteria, and protozoa, nor will it remove organic chemicals from pure water.

Reverse Osmosis

Reverse osmosis filtration systems are the most common way to create demineralized water in your home. These filtration systems reverse the natural process of osmosis to create clean, filtered water.

In osmosis, water flows across a semipermeable membrane from an area with a low concentration of solutes to an area with a high concentration of solutes. Osmosis is how the cells in our body absorb water, or how a plant’s roots draw in water from the surrounding soil. Osmosis occurs until both solutions on either side of a barrier, such as your cell wall, reach a state of equilibrium. The force causing this movement of liquids to occur is known as osmotic pressure.

Reverse osmosis involves forcing a water supply with a high amount of unwanted contaminants through a specialized membrane to produce water with fewer contaminants. Put in terms of osmosis, reverse osmosis moves liquids from a solution with a high concentration of solutes to an area with a low concentration of solutes. To accomplish this, osmotic pressure must be overcome, which is done by applying force to the contaminated water.

Reverse osmosis is a crucial filtration technology in the modern world. It is the leading method of desalination, where seawater is turned into fresh, safe drinking water. It is relied upon in agricultural, industrial, manufacturing, and food production sectors to demineralize and create purified water before it is used.

Within a residential setting, RO systems are highly effective for providing clean, filtered drinking water. Reverse osmosis systems are more cost-effective than other methods of demineralization such as distillation, as well as other services such as buying distilled or bottled drinking water. 

Though powerful, reverse osmosis systems are also small enough to be installed in tight spaces like under your sink. The best under sink reverse osmosis systems are capable of providing up to 75 gallons of drinking water per day. When weighing reverse osmosis vs distilled water systems, reverse osmosis systems are far more effective at providing on-demand filtered drinking water. 

Reverse osmosis systems are highly effective at removing minerals, salts, and other dissolved solids from water. If used in conjunction with a water softening system, reverse osmosis filtration will remove the sodium ions added to water in the water softening process. Combined with carbon post-filter, reverse osmosis systems effectively remove disinfectants like chlorine and their byproducts like chloramine, as well as other volatile organic compounds which can give your tap water an unpleasant taste or smell.

If you are wondering, “is reverse osmosis water safe?”, the water produced from a reverse osmosis system will have significantly fewer contaminants than the water coming out of your tap. As such, reverse osmosis systems effectively augment the treatment processes used by community water suppliers and provide an important safeguard against any unexpected rise in contaminants in the future.

Final Thoughts

The easiest demineralized water definition is simply water that has had the mineral, salt, and metal ions removed. Demineralized water is critical in a variety of manufacturing, industrial, and commercial sectors and is often stored in a demineralized water storage tank.

The most common methods of producing demineralized water are distillation, deionization, and reverse osmosis. While distillation and deionization are highly effective, they tend to be better suited for large-scale applications. Within a residential setting, reverse osmosis systems are equally effective at removing minerals from water. Additionally, reverse osmosis systems are most cost-effective and are capable of removing other contaminants in your tap water, such as volatile organic compounds, while still being small enough to be installed under your kitchen sink and capable of producing up to 75 gallons of drinking water per day.

To learn more about the best under sink reverse osmosis systems by Rayne Water, please contact Rayne Water today.

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Expert Reviewer – Ken Christopher