All There Is To Know About Reverse Osmosis

14 Oct.,2022


Reverse Osmosis Membrane Elements

Reverse osmosis (RO) is a popular and reliable method for ensuring that you have great-tasting filtered water on demand. In this article, we’ll explore the ins and outs of RO, including:

  • What is reverse osmosis?

  • How does reverse osmosis work?

  • How does a reverse osmosis system work?

  • How is reverse osmosis different from filtration?

  • What are some common substances removed by reverse osmosis?

  • Is reverse osmosis water safe to drink?

  • What is the best reverse osmosis dystem?

  • What is the lifespan of a reverse osmosis system?

  • Reverse osmosis FAQ

Read on to learn everything you need to know about RO.

What Is Reverse Osmosis?

Reverse osmosis, also known as RO, is a type of water filtration that can reduce up to 99% of the contaminants in water, including both larger particles and those that can’t be seen.* This is typically a multistage process that includes pushing the water through a specialized, semipermeable membrane. The end result is cleaner, safer water for drinking, cooking and other regular uses.

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How Does Reverse Osmosis Work?

As its name implies, RO takes osmosis, a natural process that occurs in all cell-based organisms – plants, animals and even people – and reverses it.

To understand reverse osmosis, you first need to know, “What is osmosis?” During regular osmosis, a diluted solution passes through a semipermeable membrane and flows into a more concentrated solution to equalize the concentration on either side. When your fingers become pruny after swimming in the ocean, that’s an example of osmosis. In this scenario, the water in our bodies passes through our skin and out to the water around us.

Now, here’s how reverse osmosis works:

  • Unlike osmosis, which is a passive process, reverse osmosis requires an external force, or pressure, to work.

  • Pressure is applied to a highly concentrated solute solution, such as saltwater, so it can pass through a membrane and turn into a less concentrated solution.

  • The membrane allows water to flow through but it blocks out larger molecules, like contaminants.

  • The reverse osmosis process leaves higher concentrations of solute on one side and only the solvent, or filtered water, on the other.

How Does a Reverse Osmosis System Work?

Reverse osmosis is a method that can be applied to water filtration to help reduce unwanted minerals, substances, molecules and other impurities in your drinking water. RO systems vary depending on the brand and design, but in general, they perform the following functions: pre-filtration, reverse osmosis, specialty filtration, drainage and storage.

Here are the steps of water filtration that usually take place in a reverse osmosis drinking water system:

Step 1: Pre-Filtration

The system connects to drinking water lines and uses a high-pressure pump to propel feed water through the system. Feed water passes through a series of initial filters, such as sediment and carbon filters, before the water flows into the reverse osmosis chamber. These early filters can address issues like rust, sand, and other larger particles, as well unpleasant tastes and smells from issues like chlorine.

Step 2: Reverse Osmosis

Here, the feed water is pushed through the semipermeable RO membrane.

This tightly woven membrane, which looks virtually impermeable to the naked eye, acts as a barrier to contaminants. Water is pushed up against this membrane at pressure and, depending on the weave of the membrane, only a certain percentage of contaminants can pass through. In Culligan RO systems, this high-capacity membrane can reduce up to 95% of substances during this stage.

Steps 3: Specialty Filtration

At this point, some systems also add additional filtration stages to address contaminants not covered in the prior stages alone. These options can include specialty filters like Culligan’s Total Defense cartridge, which can deal with contaminants including lead, mercury, volatile organic compounds (VOCs) and more.

Step 4: Drainage and Storage

The reverse osmosis system then drains out any waste water. (Note that different types of ROs have different levels of efficiency in terms of the amount of waste water generated, so it is recommended to look for a system with a high efficiency rating.) The treated water is then stored in the RO tank until it’s used (unless you have a tankless RO system). When the tap is turned on, some systems provide a final polishing filter to make your water as crisp and fresh-tasting as possible.

How Is Reverse Osmosis Different From Filtration?

As detailed above, RO systems typically employ a multistage filtration process that includes a specific type of filtration known as reverse osmosis, as well as other filters. The reverse osmosis process itself is a sophisticated technique that relies on specialized RO membranes and pressure.

When you compare RO systems to other types of tap water filters, like pitchers and faucet-mounted devices, the difference is fairly pronounced. Most of these simpler systems use activated carbon, while some incorporate other filter media as well. While carbon filtration can help you minimize the taste or smell of chlorine in your drinking water and address some other water issues, it likely won’t be very effective in minimizing the presence of dissolved solids, arsenic, viruses and bacteria. RO systems, on the other hand, are an effective way to broad treat water for a wide variety of potential contaminants.

What Are Common Substances Reduced by Reverse Osmosis?

A high-performing RO system can reduce a number of common contaminants that may be found in your water. These contaminants can include:

  • Particles

  • Lead

  • Mercury

  • Chromium

  • TDS (Total Dissolved Solids)

What Is Not Removed by Reverse Osmosis?

The reverse osmosis process on its own may not be able to sufficiently address drinking water concerns related to PFOS and PFOA. RO alone also might not be able to reduce the presence of volatile organic compounds (VOCs) or chloramine.

That’s why RO systems typically include several different types of filtration alongside reverse osmosis to provide you with a more comprehensive solution for your water (such as the Total Defence Cartridge referenced above). Later in this article, you’ll learn more about your options for an RO system.

Is Reverse Osmosis Water Safe To Drink?

Reverse osmosis water is a great choice for cleaner, safer water for you and your household. The Water Quality Association notes that RO water does not pose any health concerns for healthy populations. RO systems reduce particles and dissolved minerals commonly found in tap water. Moreover, reverse osmosis helps to reduce some harder-to-detect contaminants that can be harmful to your health, such as lead and arsenic. Using reverse osmosis water can help minimize health risks associated with potentially harmful substances that are sometimes found in drinking water. 

When you drink reverse osmosis water you’ll be able to smell, feel and taste the quality difference.

What Is the Best Reverse Osmosis System?

Culligan’s reverse osmosis systems are designed to make it easy for you to enjoy safer, cleaner water at home. Whether you want an endless supply of RO water or your priority is for a compact design that fits seamlessly into your home, we can help find the best system for you.

  • Aquasential® Smart Reverse Drinking Water Filtration System:

    The Aquasential Smart RO is certified to reduce 58 contaminants and offers up to

    7 stages of filtration and 12 filter options. Smart technology

    lets you track water consumption and contaminants reduced. You can also see cost savings and bottles saved from reduced use of single-use plastic water bottles.

  • Aquasential® Reverse Osmosis Drinking Water System:

    Get an unlimited supply of cleaner, safer water with a system that’s customized to your home’s specific water needs. Certified to reduce 60 contaminants, the system is designed for easy setup and maintenance. An optional integrated monitor light on your faucet can indicate when it’s time to change filters, which can last up to two years.

  • Aquasential® Tankless Reverse Osmosis System:

    The unique tankless design delivers the quality water your home depends on without taking up extra space under your sink. The filtration system reduces dissolved solids in your water by up to 95% and provides over 600 gallons of cleaner, safer drinking water per day.

What Is the Lifespan of a Reverse Osmosis System?

The longevity of your reverse osmosis system will depend on regular maintenance, though a good reverse osmosis filtration system requires little ongoing effort. Plan to:

  • Change filters in a timely fashion (typically every 1-2 years, depending on the system)

  • Sanitize the system once a year

Selecting an RO system from a reliable manufacturer and service partner is important to help keep your system running efficiently and effectively. Your local Culligan Water experts are equipped to take care of everything for you. From installation to maintenance, we can help ensure the longevity of your RO system and keep all the parts working properly. 

Reverse Osmosis FAQ

Do you have any other questions about RO that we haven’t already covered? Take a look at some of these frequently asked questions to see if you can find your answer here.

Can You Buy RO Water?

Single-use plastic water bottles contain water that has been treated with various methods, sometimes including reverse osmosis, along with other techniques. Additionally, if you choose to subscribe to a bottled water delivery service, you may be able to have RO water delivered straight to your home or office, depending on which varieties of drinking water are available in your area.

Installing an RO system at the point of use, however, ensures that you can enjoy the benefits of reverse osmosis water whenever you want. Once it’s up and running, all you have to do is turn on the faucet, and you’ll have great-tasting water straight from the kitchen sink for cooking, drinking or making beverages like tea and coffee.

Is RO Water the Same as Distilled Water?

Don’t make the mistake of confusing RO water with distilled water. They are not the same thing. 

Distilled water is treated using a combination of evaporation and condensation to remove dissolved solids. 

Both distilled and RO water are available commercially, but reverse osmosis is more commonly used in home treatment systems for drinking water. While some households do occasionally choose to go with a home distillation solution, these options tend to be less convenient, and they can require a lot of energy and owner involvement to run. RO water systems, on the other hand, make it easy to have cleaner water on demand, whenever you want it. You can even integrate remineralization options into reverse osmosis systems to customize the flavor of your water after it’s treated.

Is an RO System the Only Water Treatment Option I Need?

Depending on your circumstances, you may find that additional treatment options are necessary for your household water. RO systems are installed at the point of use, typically connected to kitchen or bathroom sinks using an under-sink or tankless configuration. They are not generally a whole-home solution.

While your drinking water may need the greatest care, there are several reasons you may want to use point-of-entry treatment options that improve water quality throughout your household. For example, if you have hard water, installing a water softener could enhance the water quality in your bathtub and shower while improving the performance of your water-using appliances.

A whole-house water filtration system can also help you address problems like staining from iron water, as well as issues related to sulfur water, which can produce an unpleasant smell wherever you find it. These can be particularly useful in homes with water from a private well.

Do you still have more that you want to learn about reverse osmosis? Are you interested in finding out how you can use an RO system for great-tasting drinking water? Contact our team today.

*Contaminants may not necessarily be present in your water.