Reverse osmosis has played a key role in providing people around the world with clean and fresh water for decades. The process originated in 1748, but wasn’t considered commercially viable until 2001. Tens of thousands of desalination plants across the globe are using reverse osmosis to desalinate water.
Our Picks for the Best Reverse Osmosis System
Removes up to 98-percent of chemicals, heavy metals, sediment, and other contaminants then adds good minerals
Modular all-in-one filter design for easy maintenance
Comes with a complete DIY-friendly installation kit
More expensive than most systems
Requires basic plumbing tools like wrenches and teflon tape
Removes solids smaller than 1 micron to purify drinking water
Introduces calcium, potassium and magnesium into purified water to remineralise it
Reduces over 74 contaminants, metals, pharmaceuticals and other chemicals
Targets chlorine and ammonia via carbon filtration
Bulky system requires space
Tank needs to be maintained and kept clean
Cheapest option in the recommended list
Eradicates traces of chlorine, sediments and other impurities from tap water
Small filtration system saves space
Ultra-Ease Filtration Replacement features for hassle-free changes
Durability complaints by some users
Lower filtration capacity compared to other systems
Why Trust Waterful.org?
Our water scientists and engineers spends thousands of hours researching, analyzing, and testing products to recommend the best picks. We only make money if you purchase a product through our links, and we never accept free products from manufacturers .
What is reverse osmosis?
Reverse osmosis is a filtration method that uses a semi-permeable membrane to purify water. This membrane separates unwanted ions, molecules, and contaminants from the water that is passed through it under pressure. This produces clean freshwater which is relatively safe for human consumption.
The term “osmosis” itself refers to the process of freshwater crossing a membrane to dilute a concentrated solution. On the other hand, reverse osmosis uses artificial pressure to force the concentrated solution (i.e: seawater or tap water) through the membrane and onto the side with freshwater
How it works.
Reverse osmosis is among the most popular water purification methods due to its easy set-up and use. The semi-permeable membrane it uses is fine enough to block unwanted ions, molecules, and contaminants, while still allowing water molecules to pass through.
The end result is water that has been stripped of disease-causing microorganisms, salts, heavy metals, and others contaminants. This makes the water taste fresher and more neutral than before, so it’s easy to understand why so many people use reverse osmosis filters.
Stages of reverse osmosis filtration
Filtering water with reverse osmosis is a multi-stage process that includes different types of filtering. These stages are carried out in the following order:
- Sediment removal: Sediments such as large rough particles and sand are removed
- Carbon stage: Chlorine and other chemicals are removed to prevent them from damaging the reverse osmosis membrane.
- Reverse osmosis stage: Dissolved solids and molecules that are larger than water molecules are removed. Most of the purification is completed in this stage.
- Remineralization stage: Reverse osmosis also strips the water of desirable minerals, so calcium and magnesium are added back into water after it has been purified.
How is reverse osmosis used.
Reverse osmosis is used in desalination plants and is an effective method for converting seawater into freshwater. It is also used in other reverse osmosis plants to decontaminate waste water commercially.
There are also reverse osmosis water purification systems available for homes. These home water filters are connected to the home’s water supply and are especially useful in places where the municipal water is unfit for consumption. The tap water in these regions could be brackish, or contain nitrates and other dissolved minerals that are undesirable, so it’s best that they are removed.
Types of reverse osmosis filters
A reverse osmosis water filter uses one of two membranes: Thin Film Composites (TFC) and Cellulose Triacetate (CTA) membranes. These two differ on the basis of their filtration ability and chlorine tolerance.
The TFC membranes can remove up to 98% of contaminants, but can treat only chlorine-free water.
The CTA membranes can withstand exposure to chlorine, but are susceptible to bacteria growth. They are able to block only 93% of contaminants, which makes them less reliable than TFC membranes.
Whole house reverse osmosis systems
Reverse osmosis is typically used to provide point-of-use drinking water in homes, however, people living in areas with heavily contaminated or brackish water may require a water purification solution that is larger in scale.
A whole house reverse osmosis system can be installed at the point where water enters the home. This allows every drop of water that enters your home to undergo reverse osmosis treatment so that you have access to purified water from each tap or shower in your home.
Every faucet in your home becomes a reverse osmosis faucet when you install a whole house reverse osmosis system.
What’s the best reverse osmosis system for me?
Anyone living in an area with contaminated or saline groundwater could benefit by getting a reverse osmosis system for their home. RO water is considered to be better than distilled water because the latter could still contain chlorine and other chemicals.
The quality of your municipal water supply should determine the kind of reverse osmosis system you will need for your home. If your water is heavily contaminated and saline, you may need to install a whole house reverse osmosis system.
If your municipal water is fit for uses such as washing and bathing, you can install a compact point-of-use reverse osmosis system to provide clean drinking water in your kitchen.
You should opt to go for a reverse osmosis filter that contains a TCF membrane if your water supply doesn’t contain high concentrations of chlorine. This membrane removes more contaminants than CTA membranes. However, you may have to use a CTA membrane if your water supply contains significant concentrations of chlorine.
Reverse osmosis often produces concentrated brackish wastewater in addition to the purified water it produces. This wastewater is usually disposed of down the drain.
However, zero waste reverse osmosis systems also exist that divert this wastewater to the home’s other faucets. This prevents water from being wasted, but forces residents to use brackish water in their kitchens and bathrooms.
Reverse osmosis system maintenance and lifespan
Reverse osmosis systems can last indefinitely with the right maintenance. The typical reverse osmosis membrane used in homes lasts between 2 and 5 years.
The pre-filters and post-filters on these systems need to be replaced annually, and other parts such as tanks and faucets can be replaced when they are worn out.
Do keep in mind that CTA membranes are susceptible to bacteria growth, so they should be checked up on regularly.
Reverse osmosis systems are still the best option available for purifying water on a large scale. It has made life easier for hundreds of millions of people, and will continue being popular until a more practical and efficient water purification method is discovered.