The word “osmosis” may well take you back to those biology lessons of your youth. Osmosis is essentially the diffusion of water molecules through a semipermeable membrane from a less concentrated solution into a more concentrated one. Reverse osmosis (RO) is a water purification process that uses a similar, but man-made membrane to remove dissolved solids, chemicals, and other contaminants from drinking water.
An RO filter pushes water through microscopic pores that block unwanted substances while letting clean water pass through. It’s highly effective, widely used, and great for many households and businesses, but not all. Woder provides a wealth of guidance and US-made alternatives through bids and long-term supply contracts to help you choose the most suitable filtration system.
What Is Reverse Osmosis?
As much as water may look clean and fresh, it often contains an entire ecosystem of tiny particles, and depending on where you live — let’s take Flint, Michigan, or Jackson, Mississippi, as examples — those tiny particles may not even be tiny.
Water filters work to remove these particles from water, but not all filters are created equal. Unlike basic filtration, which may only trap larger particles or improve taste, RO is a form of purification that leaves water at fancy restaurant-serving quality. It uses a semi-permeable membrane with pores small enough to block dissolved solids, heavy metals, and microorganisms that conventional filters often can’t catch.
So how does it all work? Well, it’s actually surprisingly simple. Pressure is applied to the water, forcing it through the membrane. The result is clean drinking water flows through, while all those nasty bits we don’t want get caught in the membrane before being flushed away in a separate waste stream.
RO technology was first developed in the mid-20th century, initially for large-scale desalination projects to turn seawater into fresh water. Still, it gradually became common in municipal treatment plants, commercial kitchens, and eventually home drinking water systems. Its ability to pull out contaminants like arsenic, nitrates, and lead has made it one of the most trusted purification methods worldwide.
However, RO isn’t perfect. Yes, it may be excellent at stripping out those harmful chemicals and metals, but in its intensity, RO can also remove beneficial minerals like calcium and magnesium while raising acidic pH levels, which isn’t great for human health.
How Do Reverse Osmosis Filtration Systems Work?
Reverse osmosis systems aren’t a single filter but rather a multi-stage process that turns murky, questionable water into clean, pure H2O. Let’s take a look at how it all works:
1. Pre-Filtration Stage
Before water reaches the all-important RO membrane, it passes through sediment filters, which catch most of the dirt, rust, and sand, and an activated carbon filter to remove chlorine and chloramine. Chlorine is common in water, usually at relatively low levels, but it can damage the RO membrane, so it needs to be removed first.
Pre-filtration also improves taste and clarity early in the process, so it’s already in much better shape when the water hits the membrane. This helps to extend the lifespan of the membrane because it doesn’t need to work to filter something that a regular filter can do, and also reduces the risk of blockages or slow filtration rates.
2. Reverse Osmosis Membrane
This is where the real magic happens. The RO membrane is typically made of three layers: a nonwoven fabric support layer, a microporous polysulfone layer, and a thin-film composite (TFC) polyamide selective layer. Each layer has microscopic pores, often around 0.0001 microns in size. To put that size in perspective, 1 micron is 0.001 mm — we are talking about astonishingly small holes here, minute enough to catch dissolved solids, heavy metals, bacteria, viruses, and most organic compounds.
After clean water passes through, the leftovers are flushed out through a waste line, and this is the beauty that separates RO filters from other contraptions. It doesn’t just trap particles on the surface; it separates pure water molecules from impurities at the molecular level, leaving water with significantly reduced total dissolved solids.
3. Storage Tank
Now, all of this can’t happen in the blink of an eye; RO filtration happens at a relatively slow rate, meaning most systems store purified water in a pressurized tank until it’s needed. This ensures you have an immediate supply when you turn on the tap, rather than waiting for the system to process water on demand. The tank keeps water fresh and maintains consistent pressure for dispensing, so filling a pot or water bottle is just as fast as using a regular faucet. While homes are usually OK with smaller tanks, commercial setups in restaurants or hotels, for example, are much larger to handle higher daily demand.
4. Post-Carbon Filtration
When a tap is turned, water leaves the storage tank and passes through a post-carbon filter, often called a “polishing” filter, which removes any residual tastes or odors that may have been picked up during storage. Stored water has a habit of picking up a slight tang, which can happen even with high-quality tanks. The post-carbon filter ensures the final product is crisp, clean, and neutral in taste.
5. Delivery to Tap
And so, the final stage is pure, beautiful water ready for consumption. RO systems usually have a dedicated faucet installed at the sink, so filtered and unfiltered water are always kept separate. Some systems go even further and include an optional remineralization stage, adding essential minerals like calcium and magnesium for improved taste and nutritional balance. This avoids the slightly “flat” taste that RO water sometimes has because absolutely everything has been stripped out, while also giving the body those much-needed good minerals that we need.
Benefits of Reverse Osmosis Water Filtration
Reverse osmosis is widely considered one of the most effective water purification methods available for residential and commercial use, with benefits going well beyond simply improving taste.
Effectiveness at Removing Contaminants
It may look clean, but the stuff that comes out of our taps is often far from it. Nearly a third of Americans have been exposed to unregulated contaminants, such as total dissolved solids (TDS), through their water, while 158 million have been exposed to per- and polyfluoroalkyl substances, commonly known as “forever chemicals.” Depending on where you live, your water quality can range from OK to almost undrinkable.
RO systems can remove 95–99% of TDS, making them one of the most thorough water treatment options for everyday use. The semi-permeable membrane can block microscopic contaminants that pass through many standard filters, including lead, arsenic, nitrates, fluoride, PFAS, pesticides, and certain bacteria and viruses, and its effectiveness has been backed up by the U.S. Environmental Protection Agency and other scientific bodies, which recognize RO as a proven method for improving water safety.
This level of purification is invaluable peace of mind — especially for families with children, elderly individuals, or those with weakened immune systems. An RO system can significantly reduce exposure to harmful contaminants in regions where water quality is inconsistent or where well water is the primary source.
Cost Efficiency Over Time
RO systems are one of those investments that may make you wince, but over time, you’ll make substantial savings — particularly when compared to the recurring expense of bottled water. Once installed, an RO system provides a steady supply of purified water for just pennies per gallon, eliminating the need for frequent store runs or delivery services. You can argue that nobody in the U.S should need to drink bottled water, but unfortunately, that is the case.
Maintenance costs are also relatively low, with filter replacements typically required only once or twice a year and membrane changes every few years, depending on water quality and usage. This predictable maintenance schedule makes budgeting easier for both households and businesses. For high-consumption environments such as restaurants, offices, or manufacturing facilities, return on investment improves even further. By replacing bottled water with in-house RO filtration, businesses can cut costs, reduce storage needs, and eliminate plastic waste, aligning both financial and sustainability goals.
Types of Reverse Osmosis Systems
Reverse osmosis systems come in several types and models, each designed to suit different space, budget, and water quality needs.
Under-Sink Reverse Osmosis Systems
The under-sink RO units are the most popular home options thanks to their compact size and relative affordability. They might look small, but they still deliver plenty of bang for their buck with multiple filtration stages — sediment, carbon, RO membrane, and post-carbon polishing — all built into a single unit. They’re ideal for households looking to improve drinking and cooking water without filtering the entire home’s supply, and most include a dedicated faucet, so purified water is easily accessible without interfering with the main tap.
Whole House vs. Point of Use RO Systems
Moving up a gear, we find whole-house RO systems, which, as you can probably guess, filter every drop of water in the home before it hits any faucets or appliances. They deliver an outstanding level of water quality, but require significant space, have a much higher initial cost, and often need a larger storage tank. They’re generally recommended for homes with poor source water quality across all uses, such as well water with high salinity or heavy contamination.
Point-of-use (POU) RO systems, by contrast, are installed at specific locations — commonly under a kitchen sink or in a wet bar — and target drinking and cooking water only. POU systems are more affordable, easier to maintain, and consume less space, making them ideal for most households where the primary concern is safe, great-tasting water at one or two taps.
When an RO System May Not Be Necessary
So, should we all rush out and get an RO system for ourselves? Not quite. While reverse osmosis systems are superb, they’re not always strictly necessary if your municipal water is already high-quality and meets all safety standards. In this case, a simpler filtration method will work fine.
Budget can also be a deciding factor, as RO systems have higher installation and maintenance costs than basic filters. Additionally, some people prefer filtration methods that retain naturally occurring minerals like calcium and magnesium, which RO systems remove during purification. In these cases, mineral-preserving filtration solutions better fit both health preferences and cost efficiency.
What Is the Downside of Reverse Osmosis Water?
It’s only fair to examine both sides and highlight some of the downsides of RO systems.
- One of the most frequently discussed concerns is that RO systems strip out beneficial minerals such as calcium and magnesium during purification, which contribute to water’s taste and provide small amounts of daily nutritional value. This can also level water tasting a little “flat” because it lacks those tiny healthy particles.
- The major issue with RO systems is that they can effectively reduce the Total Dissolved Solids (TDS) level to zero, which you might think is a good thing, but actually, it’s not. Water with a low TDS is often considered “dead water,” which isn’t considered healthy for drinking. In fact, you’re much better off going for Woder’s Advanced Selective Filtration, which removes 99.9% of contaminants but crucially keeps the vital minerals.
- Another issue is wastewater production. There’s no other way to look at it: RO systems use much more water than you would if you just turned on the kitchen tap. For every gallon of purified water produced, an RO system typically sends several gallons of concentrate — water containing the rejected contaminants — down the drain. This brine water can sometimes be repurposed for non-drinking uses like irrigation, but it represents a water loss without such measures.
- Finally, RO systems require more upkeep than simple filtration setups. Filter stages must be replaced on schedule, and the membrane needs periodic attention to maintain performance.
Maintenance and Troubleshooting of RO Systems
Filter Replacement and System Longevity
Pre-filters — including sediment and carbon — should typically be replaced every 6–12 months to prevent membrane damage and maintain water flow, while the RO membrane itself usually lasts between 2–5 years, depending on the quality of the source water and usage levels. You’ll want to follow the manufacturer’s maintenance schedule to ensure optimal performance and extend the system’s lifespan, reducing the need for costly replacements.
When to Seek Professional Assistance
Feeling up to DIY? That’s great, but some issues are best left to experienced technicians. A sudden drop in water pressure, changes in taste, or unusual noises can indicate a problem with the membrane, storage tank, or other internal components. Leaks, persistent clogging, or water that doesn’t seem as clean as before are also red flags. For businesses operating under bid contracts with Woder, periodic professional inspections can prevent downtime and ensure compliance with health and safety requirements.
The Impact of Reverse Osmosis on the Environment
RO systems also offer some tangible environmental benefits, and their popularity is growing as people become more aware of the world around them.
- Reduces plastic waste – By replacing bottled water with an RO system, households and businesses cut down significantly on single-use plastic bottles.
- Promotes sustainable consumption – Encourages the use of reusable bottles and reduces the need for water transportation, lowering carbon emissions from shipping.
- Energy considerations – RO systems generally use less energy than the production and transport of bottled water, contributing to a smaller carbon footprint.
- Wastewater management – While RO produces brine water, it can be repurposed for tasks like watering plants, cleaning outdoor spaces, or flushing toilets, making the process more eco-friendly when managed wisely.
Frequently Asked Questions
What Is the Difference Between a Regular Filter and a Reverse Osmosis Filter?
A regular filter uses physical or chemical processes to remove larger particles and some chemicals, while a reverse osmosis system goes further, using a semi-permeable membrane to remove dissolved solids, heavy metals, and microscopic contaminants.
Is It Healthy To Drink Reverse Osmosis Water?
RO water is safe for most people, but it removes beneficial minerals like calcium and magnesium, which are essential for human health. This can result in “dead water,” which is depleted of the key minerals our bodies need to thrive.
Which Is Better, Distilled or Reverse Osmosis Water?
Both produce highly purified water. Distillation uses heat to evaporate and condense water, while RO uses membrane filtration. RO is generally faster, more energy-efficient, and better suited for continuous household use.
Reverse Osmosis Systems Deliver Purification but Remove Beneficial Minerals
Reverse osmosis offers powerful purification, removing a wide range of contaminants for cleaner, safer water. However, it’s not always necessary, especially when the source water is already of high quality. It also strips away healthy minerals and nutrients that the human body needs.
Woder provides US-made advanced under-sink filtration systems and competitive bids for long-term business partnerships. While RO systems blitz both good and bad particles in our water, Woder’s Advanced Under-Sink Filtration options maintain healthy minerals and nutrients while still removing 99.9% of contaminants. If you want the absolute best for your home or business, then look no further.
