Learn The Pros And Cons Of Reverse Osmosis Water Filtration Systems (2022)

Are you thinking about buying a reverse osmosis filtration system but you’re not sure how they work? Do you wonder what reverse osmosis even is, or are you concerned about drinking reverse osmosis water? Has it been a long time since ninth-grade biology when you last heard the word ‘osmosis’ and you don’t remember what that means, much less what the reverse might entail?

We’ve broken down exactly what reverse osmosis filtration is and the pros and cons of reverse osmosis water filtration so you can decide if a reverse osmosis system is right for your home without going back to high school science class. (You’re welcome).

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What Is Reverse Osmosis Filtration?

Reverse osmosis is one of the most effective forms of water filtration because unlike chemical or carbon filtration systems, which use certain materials to attract or directly target the contaminants in the water, reverse osmosis works by pushing water through a microscopically small filter material.

This semi-permeable membrane has a pore size of around 0.0001 microns, effectively only allowing the small water molecules through and catching any larger molecules of contaminants, organic materials or even salt. Originally designed to desalinate seawater and reduce high chemical contaminant material such as heavy metals, reverse osmosis is now in use in many government, commercial, military and even residential applications.

How Does Reverse Osmosis Water Filtration Work?

Normally, osmosis is the process by which molecules will pass through a membrane from a weaker-concentrated solution into a stronger-concentrated solution until both solutions are of the same concentration. Reverse osmosis is still the same fundamental osmosis process, it simply involves adding higher pressure to move the water molecules out of the stronger solution (the contaminated water) and into the weaker solution (the pure water).

Because of the microscopic pores on the semi-permeable membrane filter, reverse osmosis can not only remove the obvious, visual contaminants such as sediment and larger organic material, but it can also even remove dissolved substances from within the water. Because of how effective this water filtration treatment is, reverse osmosis will even remove beneficial minerals present in water, meaning many reverse osmosis systems will run the water back across mineral beds to add those positive minerals back into the water.

Unlike other types of water filtration, reverse osmosis does not require thermal energy but instead uses an incredibly high amount of pressure. For example, brackish water, which is saltier than fresh water but not as salty as seawater (think bays and estuaries), will require between 200 and 400 pressure-per-square-inch (psi) to push it through a reverse osmosis membrane and remove the salt. Remember that brackish water is less salty than seawater. For reference, the average water pressure in a suburban American home is between 40 and 45 psi.

Benefits of Reverse Osmosis Water Filtration

With nearly two million Americans living without basic access to safe drinking water and another 40% of Americans further filtering tap water at home, water filtration systems have become an important part of many U.S. households.

Though a massive number of cities and towns already use reverse osmosis systems for municipal water and in most places in the U.S. tap water is safe to drink, many homeowners seek additional water purification to make sure the water they drink is safe. Some of the benefits of a reverse osmosis water filtration system include:

1. Reverse Osmosis Filters Nearly All Contaminants

Unlike other forms of water filtration, reverse osmosis is considered one of the most all-around effective ways of eliminating water contaminants. Even residential-grade reverse osmosis filters can remove up to 99% of lead, asbestos and 82 other additional contaminants. Reverse osmosis systems have ended boil water advisories in communities across the world by safely treating the drinking water where traditional water filtration systems did not work.

The microscopic nature of a reverse osmosis filter membrane can filter out not only the larger contaminants most water filtration systems catch, but it can actually remove dissolved substances and minerals from within the water. This is because the membrane essentially strips the water down to basic molecules as it passes through.

2. Significantly Better for the Environment and Safer than Bottled Water

For communities for which the only other option for drinking water comes from disposable plastic bottles, reverse osmosis may be a safer and more environmentally friendly option. Though reverse osmosis wastes a lot of water (see disadvantages below), piling plastic water bottles up in landfills and polluting during the production of plastic may not be any better.

The quality of water in bottled water has been put into question in the last few years because while the U.S. Environmental Protection Agency (EPA) strictly regulates and supervises the quality of tap water, the U.S. Food & Drug Administration (FDA) has much lighter restrictions on bottled water.

3. Mineral-Less Water May Be Necessary for Certain Uses

While the ultra-purified reverse osmosis water may be more than necessary for households already provided with clean tap water, certain water uses may benefit from water filtered through reverse osmosis. For example, chefs have noticed water filtered with reverse osmosis make cooking taste better since it lacks the presence of minerals, including municipally-added fluoride.

Pet owners who raise fish and/or coral in home aquariums may want to invest in reverse osmosis systems to only give aquatic pets the purest water, free of human contaminants or added minerals.

Disadvantages of Reverse Osmosis Water Filtration

While few deny reverse osmosis filtration is one of the safest and most effective forms of water filtration available, it does come with many disadvantages. First and foremost, while reverse osmosis systems may be effective on a municipal, commercial or military level (Navy ships use reverse osmosis to desalinate water for sailors), these systems have high costs and use a much higher volume of water. Especially since most U.S. cities have some of the cleanest tap water in the world, these systems may be unnecessarily wasteful.

1. Wastes Significantly More Water Than It Produces

One of the biggest disadvantages to reverse osmosis water systems is wasted water. Studies show various reverse osmosis systems can waste between 3 and 20 times as much water as they produce. This is both wasteful on an environmental scale and for homeowners whose water bills might be significantly higher than they otherwise would be.

2. Removes Healthy Minerals Present in Water and Decreases pH

Another disadvantage of reverse osmosis water filtration is that the effectiveness with which these systems filter water does not stop at only the bad contaminants. Reverse osmosis will also remove healthy minerals such as calcium, magnesium, potassium and other bicarbonates, as well as municipally-added fluoride which is good for teeth.

Additionally, by removing these minerals, the pH of the treated water decreases, making it more acidic. While this acidity is not significant enough to affect humans, the lower pH water is much more corrosive for plumbing systems and can strip lead and copper from pipes, adding those toxic metals into the water.

3. Costly Installation and Requires Expensive Maintenance

Finally, reverse osmosis filtration systems are expensive. For homeowners, these systems have to be fully retrofitted into houses and while it is possible to do it yourself, it can be a difficult and complex process. Once a reverse osmosis system is up and running it can also be costly to properly maintain and may require professional maintenance to properly ensure safety and effectiveness.

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THIS IS AN ADVERTISEMENT AND NOT EDITORIAL CONTENT. Please note that we do receive compensation for any products you buy or sign up to via this advertisement, and that compensation impacts the ranking and placement of any offers listed herein. We do not present information about every offer available. The information and savings numbers depicted above are for demonstration purposes only, and your results may vary.

Alternatives to Reverse Osmosis Water Filtration

While reverse osmosis filtration is certainly one of the most effective forms of water filtration available, it may not be the best choice for homeowners, especially in Europe and North America where most tap water is potable (drinkable according to WHO, EU and EPA standards) and of a very high quality.

Instead, homeowners with potable tap water should consider simpler, more efficient filtration systems designed to improve taste and remove the risk of contaminants that may still be present in the tap water. One of the best choices for homeowners are activated carbon filters which trap contaminants in the activated carbon as the water passes through.

These systems are much more affordable and can be installed by nearly anyone. They also don’t waste as much (if any) water and still allow the water to retain healthy minerals.

Bottom Line

Reverse osmosis water filtration is undeniably one of the most effective forms of water filtration available today, but it was designed for providing fresh water in areas where safe water is scarce and for desalinating ocean water to make it drinkable. On a smaller, residential scale, reverse osmosis is likely unnecessary in most scenarios, especially because municipal water is safe to drink in most of Europe and North America straight out of the tap or with minimal filtration.

With higher installation and maintenance costs and significantly more water waste, reverse osmosis filtration systems are best saved for those who do not have access to any fresh water, or who require extremely purified water for specific uses.

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