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How Do Reverse Osmosis Drinking Water Systems Work?

Jul 27, 2016 | Reverse Osmosis

If you’ve ever taken a sip from a glass of water that came from the home of someone with a reverse osmosis system, you know how pure and refreshing it tastes.

Or, perhaps you have concerns about water quality and want to make sure your family is drinking healthy water that reduces contaminants as much as possible.

Reverse osmosis (R.O.) drinking water truly is the purest choice for any home. It’s water the way nature intended us to drink it.

But how exactly do these systems work, and what do they do to your home’s water?

What is Reverse Osmosis?

osmosis vs reverse osmosisOsmosis is defined as the process of molecules passing through a semi-permeable membrane from a less-concentrated solution into a more-concentrated solution.

An example or osmosis from nature is the roots of plants drawing water from the soil.

Reverse osmosis is simply the opposite of that process.

The Reverse Osmosis Process

reverse osmosis membrane diagram

Molecules are forced through a semi-permeable membrane to form a less concentrated solution. Essentially, the membrane acts like a type of filter as it has extremely tiny pores that help remove microscopic contaminants from the water you drink by straining them out.

In the case of reverse osmosis drinking water systems, the semi-permeable membrane only lets water molecules through while other contaminants are collected and flushed away.

How Reverse Osmosis Filtration Works

There’s a bit more to the process when using a reverse osmosis  system to purify drinking water.

If you’ve ever seen an R.O. system, you’ve likely noticed the three cylindrical canisters on a manifold. One of these is the membrane and the other two are carbon filters. Let’s take a closer look at what each of these cartridges do.

reverse osmosis drinking water system

Step 1: Pre-filtration

The first step in purifying water with reverse osmosis is meant to protect the membrane. It removes larger sediment, including some dissolved solids, and helps reduce chlorine.

This first cartridge is referred to as the sediment filter or carbon block filter. It helps conserve the membrane, which can get clogged by excess sediment or damaged by exposure to too much chlorine, which you’ll find in municipal water.

Reverse osmosis works best when you start with good water and then make it great. That’s why you should never use a reverse osmosis system with hard water unless it is under 10 grains per gallon. If your water is too hard, start with one of our other water treatment solutions.

We often recommend having a water softener installed before installing an R.O. system. Scale buildup from hard water can damage these systems in the same way they damage other appliances. Learn more about how hard water ruins appliances here on our blog.

Step 2: The Reverse Osmosis Membrane

Following the initial filtration comes the real magic of an R.O. system.

Your water is forced through the semi-permeable membrane under pressure. The membrane is a synthetic plastic material that allows the passage of water molecules. However, sodium, chlorine, and calcium as well as larger molecules like glucose, urea, bacteria and viruses cannot pass.

We have reverse osmosis drinking water systems that are tested and certified for reduction of:

  • lead
  • arsenic
  • copper
  • nitrates and nitrites
  • chromium (hexavalent & trivalent)
  • selenium
  • fluoride
  • radium
  • barium
  • cadmium
  • cyst (cryptosporidium)
  • total dissolved solids (TDS)

Water-Right uses thin film composite (TFC) membranes in its Eclipse™ R.O. systems and Impression Series® R.O. systems. This type of membrane is resistant to bacteria breakdown and has a high rejection rate of 95 to 97 percent on average. TFC membranes are not chlorine-resistant, which is why a carbon prefilter is used.

Steps 3 & 4:  Post Filtration and Final Polish

Before your home’s water is ready to drink, it goes through a second carbon filter (or post filter), which removes any remaining contaminants in the unlikely case they slipped past the membrane.

Then the water fills up a storage tank where it waits until you’re ready to use it.

Finally, there’s the in-line activated carbon filter, which gives your water one last polish as it comes out your faucet. This is used to remove any remaining odors or flavors that may come from the system hoses or the holding tank.

The polish is a “just in case” step to make sure the water you drink tastes incredibly fresh!

Is Reverse Osmosis Drinking Water Right for Your Home?

Soft water is excellent for cleaning, showering, and laundry. However, some people would rather not drink it. Depending on how hard your water is to start with, it could still have high total dissolved solids (TDS), which can negatively affect the taste. That’s because the hard minerals are replaced by sodium, and there may be other contaminants in your water that a softener will not remove.

A reverse osmosis system can remove that sodium along with other contaminants and dissolved solids, which makes a water softener and an R.O. system an ideal combination for most homes.

When you install a reverse osmosis system, you’ll enjoy better-tasting coffee and tea, clearer ice cubes, and pure, healthy water right from your kitchen sink. If you’re still using bottled water for drinking, you’ll be making a smart investment that saves you money in the long run and is better for the environment.

Reverse osmosis systems are commonly installed under kitchen sinks or in basements. If desired, Water-Right also offers whole home R.O. systems. So you can even wash your car with reverse osmosis water for a spot-free finish!

Get further details on reverse osmosis drinking water systems and how they work on our Evolve® and WaterCare® websites.

All Water-Right dealers are equipped to help you with your needs.

Click the links above to visit the websites of our trusted brands. You can use the ‘Find a Dealer’ tool to locate a professional near you and have an expert come to your home to evaluate your situation and determine if a reverse osmosis system is a good fit.

For those who have serious concerns about water quality or potential contamination, you can have your water tested at our Clean Water Testing center to get the answers you need.