What is Reverse Osmosis? Everything You Should Know About RO Water - AquaTru

If you’re searching for a water filter that delivers clean, healthy, great-tasting water for your home or business, you’ve likely run into a common term: Reverse Osmosis. But what is Reverse Osmosis and why has it become the gold standard in water filtration? We’ll answer some of the most common questions about Reverse Osmosis so that you can better understand this method of water filtration.

What is Reverse Osmosis?

Reverse osmosis, commonly referred to as RO, is a water filtration method that uses pressure to push water through an ultrafine membrane that removes ions, molecules and larger particles from water. Considered the gold standard in water filtration, Reverse Osmosis filtration removes the widest range of harmful contaminants from tap water. 

Chances are you have tried reverse osmosis water before since many of the biggest brand names in bottled water—Aquafina, Dasani, Nestle Pure Life—use reverse osmosis to filter tap or municipal water. The process not only removes harmful contaminants from water, but it also reduces salts, chlorides, and contaminants that affect taste. Many water bottle brands add minerals back into the water after filtering to create their signature taste. We often buy bottled water without thinking twice about the price, but did you know that we pay more for bottled water per gallon than we do for gasoline? An average cost for a 16.9 ounce bottle of water can range from $0.79 to $1.99. That’s the equivalent of $6-15 per gallon! Drinking bottled water daily can cost a household a whopping $1,350 a year. Since bottled water is essentially filtered or purified tap water, which comes free-flowing out of our taps for pennies on the dollar, many turn to household RO systems to purify their own water at home, saving time, money, and plastic waste. 

How Does Reverse Osmosis Work?

Now that you know what it is, let’s look at how exactly reverse osmosis works. Before we get to the specifics, know that Reverse Osmosis uses a semipermeable membrane and the process of—you guessed it—osmosis.  

Been awhile since your high school lesson on osmosis? Here’s a recap:

Defining osmosis

Osmosis is a naturally occurring process. It’s what plants use in their roots to absorb water from soil, and is essential to the life processes of many animals (including humans). Through osmosis, molecules of a solvent (a liquid containing dissolved substances) pass through a semipermeable membrane from a less concentrated solution to a more concentrated solution. In other words, a weaker saline solution will move towards the stronger solution, eventually equalizing concentrations on each side of the semipermeable membrane. 

Semipermeable membrane: A membrane that allows some molecules to pass through, but not all. Think: a screen door or coffee filter. 

Total Dissolved Solids or TDS: TDS is a  measurement of all organic or inorganic matter that is dissolved in water. This includes substances like salts, minerals, metals, ions and other organic matter and is generally expressed in parts per million (ppm) or milligrams per liter (mg/L). 

Imagine you had two containers side by side containing different concentrations of salt and they were separated by a semipermeable membrane. The solution in the container with low salt or low TDS concentration, would pass through the membrane to dilute the container with a higher concentration of salt (or high TDS) until both sides have the same concentrations.

In Reverse Osmosis, the process of osmosis works in the same manner—just in reverse. 

Reverse osmosis

The semipermeable membrane used in reverse osmosis filters is an ultrafine mesh-like material that can only allow the smallest molecules through. Therefore,unlike the natural process of osmosis, pressure is required for Reverse Osmosis to force it through the filter.As a result, the pressure pushes water from the higher TDS concentration container through this semipermeable membrane into the low TDS concentration container.  In doing so, the  dissolved salts, minerals, metals and other molecules are trapped in the membrane, while the water molecules are allowed to pass through. 

Going back to the coffee filter example, consider Reverse Osmosis like the plunger portion of a French press—only using a much higher level of pressure. Like the coffee grounds that are trapped in the filter, the semipermeable RO membrane captures around 95-99% of dissolved salts and other molecules. The trapped molecules and any remaining water can be considered reject water, and everything else can go onto further treatment to end up as a crisp, cool glass of filtered water. 

What Contaminants Does Reverse Osmosis Remove from Drinking Water?

On its own, the process of Reverse Osmosis can trap and remove a range of harmful organic and inorganic contaminants.These include (but aren’t limited to):

  • Aluminum
  • Asbestos
  • Arsenic
  • Copper
  • Chromium
  • Chloramine
  • Chloride
  • Dissolved solids/salts
  • Hexavalent chromium
  • Lead
  • Nickel
  • Nitrates
  • Protozoa (i.e., Giardia, Cryptosporidium)
  • Sulfates

 However, many Reverse Osmosis systems have additional stages to reduce even more contaminants that can’t be captured by a physical membrane. Other contaminants that can be found in water are VOCs or volatile organic compounds, which are chemicals that we often see in gaseous form but can also dissolve in water. These contaminants cannot be measured in terms of TDS and require a different kind of filter in order to effectively remove them from drinking water.

What is a Multi-Stage RO System?

The semipermeable membrane used in a RO system is just one line of defense against harmful tap water contaminants. While it’s effective in removing most organic compounds like metals and nitrate, many RO systems also make use of pre-treatment and post-treatment filters. Both AquaTru under-sink and countertop reverse osmosis water purifiers use 4-stage Reverse Osmosis technology. 

With these, not only does a pre-treatment and carbon filter (Stage #1-2) reduce larger particulates, sediment, and scale-causing compounds. They will also reduce chlorine taste and odors before the water is treated by the Reverse Osmosis membrane. 

After the water passes through the semipermeable reverse osmosis membrane (Stage #3) to remove all of those ions and metals previously discussed, it’s filtered once again in Stage 4—this time through a high-quality activated carbon filter that reduces VOCs. Volatile organic compounds in water could include those from agricultural runoff, industry spillage, and many household products, like paint and upholstery. This post-treatment (Stage #4) filter reduces common waterborne VOCs like trihalomethane (TTHs), PCE (perchloroethylene), and MTBE (methyl tert-butyl ether). 

Working together, a multi-stage RO system will address the widesti spectrum of contaminants—and do so at a more thorough level than a single system can address on its own. Each filter will also enhance taste and prepare the water for safe consumption. 

Is RO Water Good or Bad for Your Health?

Since its so effective at removing contaminants, does Reverse Osmosis remove the good components, too? Is it possible to have too much of a good thing?

We’re here to quell concerns for all of those asking, “Is RO water bad for your health?”  Put simply, Reverse Osmosis systems make our water safer to drink. The method doesn’t produce water that is carcinogenic, nor does RO filtered water present a potential risk to our kidneys. RO water isn’t banned in Europe either. 

Perhaps the most  common misconception about drinking Reverse Osmosis water is that it strips the body of minerals. This simply isn’t true. 

While RO systems do remove more than 90% of minerals, the majority of healthy minerals needed for the human body are sourced through food or dietary supplements—not water. Not only that, but the minerals found in water include mostly inorganic minerals, whichare difficult for the body to absorb. 

With a proven capability of removing some of the most harmful contaminants that pose a known risk to our health, including lead, arsenic, uranium, radium, Trihalomethanes (TTHs), PFAs and so many more,   multi-stage Reverse Osmosis filtration provides the broadest spectrum of protection against these harmful contaminants, to produce water that is undoubtedly good for your health. 

However, if you feel that you could benefit from minerals in your drinking water or just prefer the taste of mineral water, many systems include a mineral boost in the final stage of the filtration process to add healthy minerals back into the water, or you could add mineral drops into your water after filtration

What is Certification and Why is it Important?

The market is filled to the brim (pun intended) with Reverse Osmosis water filtration systems. So how should you go about choosing the best one?

In addition to considering different designs (i.e., under-sink and countertop) and prices, one of the most important factors when deciding on any water filtration product is certification to NSF/ANSI standards. 

NSF (National Sanitation Foundation) International is a third-party organization that creates national standards for drinking water, food, and other consumer products. They also do in house testing and certification. However, once these standards are created by NSF, a select group of 5 organizations are accredited by ANSI (American National Standards Institute) and allowed to independently test and certify products to NSF standards.  ANSI oversees standards and conformity assessment activities in the United States.

U.S. states accept certified testing from 5 different labs: NSF International, IAPMO (International Association of Plumbing & Mechanical Officials), WQA (Water Quality Association), UL (Underwriters’ Listing), and CSA Group. These 5 labs have been accredited by ANSI to be certified to NSF standards. 

In order to maintain certification status, all of these organizations also require regular audit and inspection of the products, warehouses and factories to ensure a company continues to meet NSF/ANSI standards. 

You want to look for certification to NSF standards when shopping for water filtration products, but they can be certified by one of the following organizations: NSF International, IAPMO, WQA, UL, or CSA Group. “NSF certified” means it was specifically tested and certified by the organization NSF International, but certification to NSF standards by any of those five organizations all carry equal weight because they are all accredited by ANSI and held to the same NSF standards, rigorous testing and auditing to keep consumers safe.

Be wary of products that only claim that they have only been internally tested, independently tested, or even “independently tested to NSF standards”, but are not certified to NSF standards. This means that they have not received certification by one of the 5 aforementioned labs that test, enforce and audit NSF standards.

Summary: Is an RO System Worth It?

There are several reasons Reverse Osmosis is considered the gold standard when it comes to pure, healthy, crisp-tasting water. There’s nothing like a Reverse Osmosis system in ridding water from harmful contaminants. 

However, Reverse Osmosis filtration in a household typically involves the installation of under-the-sink systems that directly connect to your plumbing. This can be costly—whole house RO systems can cost up to $7,500 depending on the size of the home! While the cost of a basic under sink RO system can vary widely, there is a hidden cost in having a plumber install the system and paying them to regularly change your filters throughout the year. Getting pure, healthy RO water doesn’t always have to be such a headache (or take such a toll on your bank account) though.

At AquaTru, our revolutionary countertop purifiers provide any home with the power of reverse osmosis purification without any plumbing or installation. You won’t need the help of costly plumbers to install the system or change your filters. Compared with RO water from bottled water companies, you’ll save thousands of dollars annually—and support our planet in the process. 

AquaTru countertop purifiers are also more efficient than traditional under sink systems—which waste upwards of 3-5 gallons of water for every gallon of pure water produced! Thanks to our patented Ultra Reverse Osmosis® technology, for every gallon of tap water, AquaTru Classic purifiers produce ¾-gallon pure water. You can use the ‘waste water’ for other sustainable uses, too!

If you own your home, we also have under sink systems that you can install for unlimited pure water on-demand right with a dedicated faucet right at your kitchen sink. And the best news is our filters are designed to be easily changed, so there’s no need for expensive professional visits just to change your filters. With a simple twist of the wrist, you can replace your filters in mere seconds.

There is also a dirty secret about under sink RO systems that is not commonly known. Under sink RO holding tanks can be a breeding ground for bacteria, if not properly maintained. Most people don’t realize they need to sanitize their tank once per year, and when they do, the process usually involves tubing and a plastic syringe. That’s why we at AquaTru developed our own patent-pending, TruPure RO Sanitizer that makes it easy to keep your AquaTru holding tank in pristine condition. Simply unscrew the TruPure RO Sanitizer, pour in the sanitizing solution, and complete the remaining sanitizing steps only once per year when you change your VOC filter. Just another way AquaTru ensures that you have pure, great-tasting water.

Making Reverse Osmosis Water Accessible to All 

AquaTru is a great solution to those looking for healthy water and the widest protection against harmful tap water contaminants. Not only are we committed to the safest certified water, but we’re dedicated to getting it into as many households as possible. In recognizing that an optimized life starts with clean water, we donate a portion of our sales to provide AquaTru Reverse Osmosis purifiers and filters to communities in need around the country. 

AquaTru has worked with Second Chance Church to donate purifiers and filters to community members affected by the Flint water crisis. We have also donated $50,000 this year to support the Navajo Water Project, an Indigenous-led clean water project by human rights nonprofit DigDeep. We’ll continue to be clean water warriors for the greater good—and that starts with our effective and affordable Reverse Osmosis systems for all. 

Congratulations, you’re now an expert on the question, “What is reverse osmosis?” Reverse Osmosis is a superior, all-around effective method for reducing harmful contaminants that can be found in our tap water. Utilized in a multi-stage system, an RO filter can produce the purest, most delicious water around. Turn to one of AquaTru’s Reverse Osmosis water purifiers to see for yourself.