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Reverse Osmosis Vs Distilled


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

If you are looking at options for purified water you have probably come across the suggestion to use a reverse osmosis water purification system. You might have also seen people recommend drinking distilled water if you are worried about organic contaminants. If you’ve ever wondered the difference between distilled and purified water, distillation is just a type of water purification. So, instead of thinking of this as purified vs distilled water, it is a better representation to think of distilled water under the umbrella of purified water.

Reverse osmosis and water distillation are common methods for water purification, but what are these differences between these two purification methods, and which is better? While water distillation is an older purification process, there are several key factors making it less desirable for home water purification. Understanding the differences between reverse osmosis vs distilled water can help you determine which water purification method is right for you.

What is Distilled Water?

Distilled water is water that has gone through the process of distillation. In order to distill water, you boil it, capture the steam that rises from the water, then allow the steam to condense and fill another container.

Put another way, the distillation process involves turning liquid water into a gas and then reforming it as a liquid again. This type of treated water requires a piece of equipment known as a still. Modern distillation units are fairly straightforward in operation by automating the process.

Distillation is used as a means of water purification. Purification is the process of removing certain contaminants from water, so distillation is a method of reducing contaminants and producing clean water. Like other methods of water filtration or purification, distillation is unable to remove all organic contaminants on its own.

Distillation is effective at removing dissolved solids in water, such as minerals and salts. These substances make water hard and lead to scaling. Distillation is also excellent at neutralizing microbes such as giardia or Legionella from water. Distillation is less effective at removing chemicals with a boiling point near water. To remove these chemicals, distilled water will need to be run through an additional filtration process.

Distilled water is necessary for the operation of certain types of equipment. You’ll see it required for use in equipment that may be damaged by mineral deposits. Distilled water is used in a residential setting for use in an electric iron or steam mop, as well as in automotive cooling systems and certain types of batteries.

What are the Disadvantages of Distillation?

Although distillation can provide some purification benefits for tap water, there are some downsides to consider as well. When comparing reverse osmosis water filter vs distilled water, the biggest disadvantages of distillation are speed and energy costs. Home distillation systems require high amounts of energy to run, resulting in higher ongoing costs when compared to alternatives like reverse osmosis.

Distillation systems are at a disadvantage for providing drinking water on demand. While the best under sink reverse osmosis system can produce up to 75 gallons of drinking water each day as needed, distillation takes time. Water must be brought to a boil, and steam must condense and collect in a storage container. 

The second disadvantage of distilled water is most people do not enjoy drinking it. Distilled water has been demineralized, and is often described as flat or bland in taste. For people wondering, “what is demineralized water?”, it is simply water with the dissolved minerals and salts removed. Minerals and salts like magnesium and calcium, which harden water, also give it some of the taste many of us have come to expect. Since distillation nearly completely removes any mineral content in water, many people find the taste strange. 

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What is Reverse Osmosis Filtration?

Reverse osmosis is one of the most common water filtration systems in both residential and industrial settings. Reverse osmosis is used by millions of people to provide clean, filtered drinking water. It is also used in desalination plants to turn seawater into freshwater, in industrial agriculture to give greater control over the PH of the soil, in the production of pharmaceutical products, and in food and beverage production.

The best way to understand the reverse osmosis process is by getting a sense of how osmosis works first. Osmosis is a natural process involving the movement of solvent from a solution with a low concentration of solutes to a solution with a high concentration of solutes across a semipermeable membrane. This movement is due to a force known as osmotic pressure.

  • Solutes – Dissolved particles in a solution.
  • Solvent – The liquid in a solution.
  • Solution – Solute and solvent combined.
  • Semi-permeable membrane – This is a membrane allowing some substances to pass but not others.

The point of reverse osmosis water is to achieve equilibrium on both sides of a membrane. When one side has a higher concentration of solutes and a lower concentration of liquid, the liquid flows from the other side until the solution on both sides of the membrane is the same.

Osmosis is how plants get nutrients from the ground. The soil is a solution with a low concentration of solutes, and the plant has a high concentration of solutes. Water flows through the semipermeable membrane of the roots into the plant.

In reverse osmosis, this entire process is reversed. Reverse osmosis starts with a solution with a high concentration of solutes. For water purification, this is water with a large number of contaminants. This contaminated water is forced at high pressure across a semipermeable membrane. The semipermeable membrane has tiny pores that allow water molecules to pass through but keep other contaminants out. 

One of the easiest ways to visualize the reverse osmosis process in action is through the desalination process. Desalination plants force seawater, which has a high concentration of salt, across a semipermeable membrane that allows water molecules to pass but keeps salt out. What’s left on the other side is, potable, fresh water.

If you are wondering, “is reverse osmosis water safe?”, the answer is reverse osmosis water has far fewer contaminants than unfiltered tap water.

Reverse osmosis as a filtration process on its own is effective at reducing or removing a number of contaminants. These include:

  • Minerals
  • Salts
  • Microbes

Reverse osmosis systems within a residential setting sometimes have pre- and post-filters as well. The pre-filter reduces any sediment in the water before it passes through the membrane. This helps extend the lifespan of the membrane. The post-filter uses granulated activated carbon (GAC), which captures some contaminants reverse osmosis systems aren’t as effective against. These include disinfectants like chlorine, disinfection byproducts, volatile organic chemicals (VOCs), synthetic organic chemicals (SOCs), and other substances which alter the taste or smell of water.

There are a couple of important things to briefly note about residential reverse osmosis water filtration systems. The first is they aren’t 100% efficient. A small amount of water is flushed down the drain along with any contaminants collected during the reverse osmosis filter process. The second thing to note is you will occasionally have to replace the filters and RO membrane in the system. This is usually a simple process with minimal system downtime but is essential to ensure your system continues operating at peak performance.

When weighing the choice between reverse osmosis water filter vs distilled, keep in mind both types of systems produce some type of wastewater. In both types of systems, the contaminants and impurities collect on one side of the process and must be flushed from the system.


How are Reverse Osmosis Systems Used?

If you want clean, purified drinking water in your home then a Rayne Water reverse osmosis water filter system is the way to go. Reverse osmosis systems come in two configurations. The more common configuration is known as a point-of-use (POU) system. POU systems are designed to provide filtered water at a single tap, such as at your kitchen sink. 

Reverse osmosis purification systems tend to be ideal for this because they are small enough to be installed in tight spaces, such as under a kitchen sink. Yet these systems are still powerful enough to provide sufficient drinking water for everyone in your household. If you are weighing the advantages of reverse osmosis vs distilled, the size and on-demand power of reverse osmosis systems clearly pull ahead.

The second, less common configuration for reverse osmosis filtration is known as point-of-entry (POE) system. Otherwise known as a whole-house water treatment system, a POE reverse osmosis system is designed to provide reverse osmosis filtered water to your entire home. One of the benefits of a whole-house reverse osmosis system is having soft, clean water throughout your home. The water you shower and bathe in will also have had a wide range of contaminants and impurities removed.

However, if you want to eliminate the effects of hard water throughout your home and also have clean, purified drinking water it may be more economical to use a whole-house water softening system and a POE reverse osmosis filtration system. This setup is common because the use of water softeners eliminates the impact of hard water around your house, while the reverse osmosis system provides clean, filtered drinking water.

Closing Thoughts

Both distillation and reverse osmosis are methods of water purification, however, they function in different ways. The distillation process involves boiling water, capturing the steam produced, and condensing the steam in a different container. This process is accomplished with a specialized type of equipment known as a still. 

Though distillation is effective at removing microbes, minerals, and salts from your water supply, it leaves water tasting flat and bland. Distillation as a process is simply too slow, cumbersome, and inaccessible as a method of home water purification except in emergencies.

In contrast, a reverse osmosis water filtration system forces water containing contaminants across a specialized semi-permeable membrane at high pressure. In a reverse osmosis system, the membrane is designed to allow water molecules to pass through but not other contaminants. Combined with an activated carbon post-filter, reverse osmosis systems are capable of removing minerals, salts, and microbes from water, along with many organic and synthetic chemicals, and disinfectants, and their byproducts.

Unlike distillation, reverse osmosis is accessible for all homes. RO systems can be installed at a single tap and provide a sufficient amount of clean, fresh water for an entire family. Reverse osmosis systems are much more cost-effective than bottled water delivery services and offer a high level of protection against any unexpected rise in contaminants.

To learn more about residential filtration systems with reverse osmosis or if you’re interested in commercial reverse osmosis systems, please contact Rayne Water today. 

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Expert Reviewer – Ken Christopher