Reverse Osmosis Water Filtration Explained

Reverse osmosis water filters are a popular choice for many homeowners. Many of these systems use multiple filtration stages to remove everything from lead and arsenic to hormones and bacteria from water. It’s no wonder why the EPA considers reverse osmosis (RO) one of the best water filtration technologies on the market.

From residential homes to large-scale plants, RO water filters are at the forefront of clean, high-quality filtered water. At the heart of these systems is a reverse osmosis membrane that is so fine that it captures even the smallest particles from your water supply, leaving you with fresh, contaminant-free drinking water.

Typically, RO systems are designed to be installed under the sink and include a water dispenser mounted on the sink or countertop. There are also countertop RO systems and other water filters for sinks that are ideal for renters or anyone who doesn’t want to drill into their counters or cabinets. These systems often provide fresh, clean filtered water on-demand. But if you have a large family with a high demand for better water, high-output RO water filters are your best bet.

Now, before you take the plunge and purchase a new RO water system, it’s essential to know a thing or two about reverse osmosis. Luckily for you, today we’re taking you behind the scenes for a closer look at reverse osmosis and how it works. Stay tuned!

What is Reverse Osmosis?

reverse osmosis drinking system
SpringWell’s Reverse Osmosis Filter System

Reverse osmosis, or RO for short, is a process that uses intense water pressure to force the source water through a semipermeable membrane that leaves the solid contaminants behind on one side while allowing the water molecules to pass on the other side.

Think of a screen door. It allows air molecules to pass through but not pests or anything larger than the holes in the screen door. In the same way, the RO membrane has small pores that allow the source water to pass through it while “screening” objects that are too big to pass through.

How Does a Reverse Osmosis Filter System Work?

Reverse osmosis is the reverse of osmosis. As you probably can recall from science class, osmosis occurs naturally without any energy. However, to reverse the osmosis process, you need to apply adequate pressure to the more concentrated solution to “push” it through the RO membrane.

Usually, a high-pressure pump is used to increase pressure on the RO membrane’s concentrated side and force the water across the membrane, leaving almost all the contaminants behind in the reject stream. Of course, the amount of pressure depends on the source water (aka, the feed water) concentration. The more concentrated the feed water, the more force is required to overcome the natural osmotic pressure.

Here’s a brief breakdown of how the process works:

  • When the feed water first enters the RO system, it goes through prefiltration. Prefiltration typically includes a sediment filter and a carbon filter to remove sediment, chlorine, and other pollutants that could clog or damage the RO membrane.
  • Next, the water enters the RO membrane under pressure (enough to overcome osmotic pressure). The water molecules pass through the semipermeable barrier, while the dissolved contaminants cannot pass through. The water that makes it through the RO membrane is called the product water or permeate. It usually has around 95% to 99% of solid contaminants removed from it. Conversely, the system discharges the rejected pollutants through the reject stream. The reject stream either goes to the drain or is fed back into the feedwater system to be recycled through the RO system.
  • After filtration, the water flows to the storage tank, where it is held until needed. A reverse osmosis system continues to filter water until the storage tank is full, then shuts off.
  • Once you turn on your drinking water faucet, water comes out of the storage tank through another postfilter to “polish” the water before it gets to your faucet or appliance. Inline water filters are excellent post-filters. They are usually installed under the sink, out of sight, unlike filters that attach directly to the kitchen faucet. Inline water filters are also suitable for refrigerators, ice makers, coolers, washing machines, water fountains, boats, etc. The good thing about inline water filters for sinks is that they are always operating. That means there is no needed action other than turning the handle on your faucet. The best inline water filters usually have high filtering capabilities for a safe and healthy water usage experience. They also are compatible with multiple appliances, are durable, and easy to install and replace.

What Contaminants Does Reverse Osmosis Remove from Water?

Impressively, reverse osmosis systems can remove up to 99% of dissolved salts (ions), particles, organics, bacteria, heavy metals, chemicals, and other pollutants from the feed water. But even so, we don’t recommend relying on an RO system to remove bacteria and viruses. It’s better to use a UV water purification system, such as our Springwell UV Filter System, one of the industry’s most potent UV systems. Our UV system kills 99.9% of harmful bacteria, viruses, and other pathogenic organisms from tap water, including E. coli, Cryptosporidium, Giardia lamblia, and other potentially dangerous microbes.

Here’s a list of contaminants RO filters also remove:

  • Chlorine, chloramine, chlorine byproducts
  • Fluoride, lead, mercury, iron, arsenic
  • Herbicides and pesticides
  • Sediment
  • VOCs
  • Salt
  • And many more

While RO systems can be very effective against water pollutants, it’s important to note that these systems may strip away healthy minerals that positively impact the taste and benefits of the water you drink. Luckily, some RO systems have remineralization technology that helps restore the water’s ideal pH balance and retain healthy minerals like calcium and potassium.

Benefits and Drawbacks of Reverse Osmosis Water Filters

It’s a known fact that reverse osmosis filtration has some incredibly positive health benefits. But like all good things in life, they have their share of drawbacks. The main advantages of reverse osmosis water filters are that:

  • RO systems can remove more contaminants than other types of filtration systems.
  • They can filter water down to a micron level (removing up to 99% of dissolved solids).
  • They help reduce sodium intake.
  • They reduce bad tastes and odors in the water.
  • RO water filtration systems are a safe, environmentally-friendlier alternative to bottled water.
  • They remove harmful dissolved contaminants.
  • They fit under the kitchen sink.
  • They are easy to install and maintain.
  • They provide better-quality water for cooking.

So, what about the drawbacks?

  • RO systems produce quite a bit of wastewater, wasting about four gallons for every gallon of clean water produced. However, there are “zero waste” systems that use electricity to force water through the RO membrane or recycle wastewater. Then again, this puts wear and tear and your system, so you have to replace the filters more often.
  • RO water filters tend to remove health minerals essential to your body, including magnesium, potassium, and calcium.
  • If you don’t change the prefilters as recommended, you will ruin the RO membrane.
  • The flow rates are slower than expected.
  • Your water usage will increase.
  • RO systems require proper wastewater disposal.

Should I purchase a Reverse Osmosis Water Filter?

The answer to this question mostly depends on your water quality. Before investing in an RO system, it’s best to check your water quality with a home water testing kit. You can also send a water sample from your tap to a certified laboratory in your area.

The aim here is to find out if you need an RO system, rather than jumping the gun and purchasing a system you didn’t need in the first place. Depending on your water quality and the specific contaminants detected in your water supply (if any), you can decide whether or not to make the purchase.

Another factor to consider is whether you need clean, high-quality filtered water in your entire home or just at a particular faucet or appliance. If you are looking for the latter, then an RO system might be ideal for you. Keep in mind that RO water filters are point-of-use systems, meaning they treat water down the line and specific areas in your home. However, if you need a filtering system that treats water at the entry point, you might be better off with a whole-house water filtration system.

Reverse osmosis filters are ideal for use under the sink, for a refrigerator, well, aquarium, in RVs, and at businesses. They are sometimes used for agriculture and rarely used for the whole house. But despite where they’re used, reverse osmosis systems improve the health and taste of your water. They feature multiple filtration stages and heavy metal reduction. They are also perfect for homeowners looking to address specific contamination issues with a filtering system that removes more contaminants than other water filtration systems.

The Best Reverse Osmosis Water Filter for Your Home

The best reverse osmosis water filter for your home is one that has carefully engineered membranes that stand up to daily use. It filters out even the smallest impurities and includes additional stages to ensure the water it provides is clean and healthy.

Standard RO filtration systems generally do an excellent job of stripping away contaminants, chemicals, minerals, and salt. But during the process, they also strip the water of essential minerals. Although some health experts suggest the concentration of essential minerals in water is negligible, others (including some at the World Health Organization) believe water is a vital source of minerals, such as calcium, magnesium, iron, and potassium, especially for people in developing countries. As such, the best osmosis water filter removes all the harmful particulates while remineralizing the water. That assures the water not only tastes great but has all the health benefits that essential minerals provide.

If you determine you need an RO filter for your home, our SWRO Reverse Osmosis Systems might be an excellent fit. They are carefully engineered and designed to remove harmful contaminants – including lead, fluoride, chromium-6, arsenic, etc. – and produce fresh, clean, great-tasting water for you and your family.

Both models are 4-stage point-of-use systems that can fit neatly under your kitchen sink. All you need is a separate spout to dispense all your drinking water. You’ll also love that our RO systems have an excellent working pressure and flow rate, which means you won’t experience any significant decreases in water pressure, if any at all. On top of that, both models produce up to 75 gallons of fresh, clean filtered water. They’re also easy to install and maintain, which is always a plus.

When you purchase one of our high-performance RO water filters, you get a six-month money-back satisfaction guarantee, a lifetime warranty on the tank and valves, free, fast, and reliable shipping, factory-direct savings over 50%, and affordable financing. But most importantly, you’ll have the peace of mind of knowing you have one of the most efficient, reliable, and durable RO water filters on the market in your home. Check out our RO filter page to learn more about how our RO systems can transform your tap water into the cleanest and highest-quality drinking water available.

Final Thoughts

Reverse osmosis is a highly effective and proven water filtration technology suitable for many household and industrial applications. With a proper RO unit in your home, you can benefit from water that’s not only pure but has no foul odor or taste. Some RO systems also make your meals more delicious! Should you decide to purchase one of these home-changing devices, reach out to us for help finding the one that best suits your needs. Plus, if you have any questions or concerns on anything regarding reverse osmosis, we’re here to provide all the information you need.