How does the reverse osmosis water system work?

A reverse osmosis water system is a water purification system that uses a semipermeable membrane to remove contaminants found in the water.

It uses water pressure to force water through a semipermeable membrane where contaminants are flushed into the drain and clean water passes through.

The process is capable of removing 99% of total dissolved solids contaminants in water, including lead, fluoride, heavy metals, and chlorine.

How does the reverse osmosis water system work?

Reverse osmosis systems are available in two types modern and old. Modern model work differently compared to old ones.

In this article, we will discuss how both modern and old reverse osmosis system work.

The old reverse osmosis system is commonly known as the under-sink reverse osmosis system. The modern model includes such as countertop and tankless reverse osmosis systems.

How does the under-sink reverse osmosis water system work?

A standard under-sink reverse osmosis water system involves different stages to filter out contaminants in the water. Each stage uses a specific filter.

The stages include

Stage 1: Include a sediment filter that helps to remove sand, silt, dirt, and rust. The sediment filter protects particulate from getting to the delicate RO membrane.

Stage 2 includes a carbon filter that helps remove chlorine, taste, and odor.

Stage 3 includes the reverse osmosis membrane, which is the heart of the reverse osmosis water system. The RO membrane helps filter out 99% of the total dissolved solids (TDS) found in water. Such contaminants include lead, fluoride, pesticides, mercury, arsenic, hard water minerals, nitrate, and total dissolved solids. At this stage, contaminants larger than 0.0001 microns are removed.

Stage 4: Include a carbon post filter or polishing filter. It helps remove any remaining taste and odor in the water before it gets to the faucet.

Water gets into the sediment filter and all particulates are removed. Sediment protects the RO membrane from particulates that can clog the system. Then it goes to a carbon filter where the chlorine taste and odor are removed. Chlorine can damage the RO membrane.

Both sediment and carbon filters are pre-filters. They help extend the life of the RO membrane.

After the pre-filter, the water goes through a reverse osmosis membrane, which is the heart of the system. At this stage, high water pressure is required to push water through the RO membrane, so the incoming water pressure should be above 50 psi. If below 50 psi, the system will not remove contaminants effectively, leading to low water quality and rejecting more water to the drainage, resulting in high water bills.

To increase the pressure, you can decide to install a booster pump to increase the pressure. Increased pressure helps the system produce high-quality water, reduce water waste, and fill the tank.

You can install a pressure gauge before your RO membrane to know the exact incoming water pressure on your membrane.

After the water passes through the semipermeable membrane, the purified water goes into a pre-pressurized storage tank where it is stored waiting for human consumption. Contaminants are flushed down the drain.

When you open the faucet, the water passes through the final filter called the post/polish filter. The post-filter helps remove any taste and odor the water might have picked up from the storage tank.

Why do you need a storage tank?

The reverse osmosis system treats water slowly. So the whole process takes a long time before it produces purified water.

You need a storage tank that will collect purified water that is gradually treated. Without the tank, you can end up waiting a long time to fill a glass of water or a pot when you open the kitchen faucet. The tank collects water so you can have immediate access to treated water.

Some systems have an additional filter, such as a remineralization filter, that is installed after the post filter. An RO membrane is known for stripping beneficial minerals that our body requires, such as calcium and magnesium.

The remineralization stage helps add those beneficial minerals.

Shop for an RO system with remineralization.

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4SimPure SimPure T1-400 UV Reverse Osmosis System Buy Amazon
5Rinkmo Rinkmo Reverse Osmosis Water Filtration SystemBuy Amazon
6Reverse osmosis revolution Alkaline Alkaline (Raise pH Level) 5-Stage Countertop Reverse Osmosis Water Purification SystemBuy Amazon
7Frizzlife Frizzlife RO Reverse Osmosis Water Filtration SystemBuy Amazon
8Ukoke RO75GPUkoke RO75GP 6 Stages Reverse Osmosis Water Filtration SystemBuy Amazon
9AlcaPure AlcaPure Reverse Osmosis Countertop Water FilterBuy Amazon
10NU Aqua Platinum Series 100GPD Under Sink Reverse Osmosis Drinking Water Filtration System NU Aqua Platinum Series 100GPD 6-Stage Undersink Reverse Osmosis Buy Amazon

Other systems have an additional UV filter. A UV filter is the last stage where water runs in UV light before dispensing to the faucet. It helps eliminate bacteria, viruses, and protozoan cysts.

Also, a storage tank can be a breeding zone for bacteria and viruses. Before water dispenses from the faucet, UV light is required to eliminate bacteria, viruses, and algae.

Shop for an RO system with UV light.

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1Waterdrop N1 Countertop Reverse Osmosis Water Filtration SystemWaterdrop Waterdrop WD-N1-MRO Filter
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Standard under-sink RO systems go through the above stages.

How does the under sink Reverse Osmosis drinking water system work?

How do countertop and tankless reverse osmosis systems work?

There are modern types of reverse osmosis systems, such as countertop and tankless reverse osmosis systems, that work differently from under-sink systems.

Both countertop and tankless reverse osmosis systems utilize 4 stages (sediment filter, Pre-carbon plus filter, RO membrane filter, and post-carbon block filter), but they don’t have a tank where water is stored.

Water goes through 4 stages of filtering and is filtered faster, unlike the traditional RO system where the process takes longer. You get filtered water right away from the faucet.

Modern systems have a compact design that takes less space, and the water is not stored in the storage tank, which poses a risk of secondary pollution and requires no installation.

The drawback of the tankless and countertop RO systems is that they require electricity to operate compared with the traditional under-sink RO system that uses incoming water pressure.

Watch the video on how the tankless reverse osmosis water system works.

Shop for a tankless RO system.

NameImageFeaturesWhere to buy
1Frizzlife RO Reverse Osmosis Water Filtration System – PD600-TAM3Frizzlife RO Reverse Osmosis Water Filtration System tankless3stages filtration
Replacement filters
Alkaline remineralization
Brushed nickel faucet
1.5: 1 drain ratio
600 GPD
Smart LED Display
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2Brondell Circle Reverse Osmosis SystemBrondell Circle Reverse Osmosis System4-stage
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3Waterdrop G2 RO Reverse Osmosis Water Filtration System WD-G2-WWaterdrop G2 Reverse Osmosis System NSF Certified
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4 SimPure RO Reverse Osmosis Water Filtration SystemSimPure Q6 Tankless Reverse Osmosis Water Filtration System4stages filtration
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5Frizzlife RO Reverse Osmosis Water Filtration System PD600 Frizzlife RO Reverse Osmosis Water Filtration System3stages filtration
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6Oasis osmosis home RO Reverse Osmosis Water Filtration SystemRO Reverse Osmosis Water Filtration System, Countertop or Under Sink Tankless 3stages filtration
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7iSpring RO500 Tankless RO Reverse Osmosis Water Filtration SystemiSpring RO500-BN Tankless RO Reverse Osmosis Water Filtration System,Twist and Lock Filters
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8GreatWell ROG400 Tankless Reverse Osmosis Water Filtration SystemGreatWell ROG400 Tankless Reverse Osmosis Water Filtration SystemTwist and Lock Filters
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9KFLOW Reverse Osmosis Water Filtration SystemKFLOW Reverse Osmosis Tankless Water Filtration System5 stages filtration
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Watch the video to see how the countertop reverse osmosis water system works.

Shop for countertop RO system

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1KFLOW Countertop RO Water Filter (KFL-ROPOT-180)KFLOW Reverse Osmosis System, Countertop RO Water Filter stage 1, stage 2, stage 3 & stage 4Buy Amazon
2Frizzlife Countertop RO water filterFrizzlife RO Reverse Osmosis Water Filtration SystemCartridgeBuy Amazon
3Reverse osmosis revolution Countertop Portable  Countertop Portable Universal 5-Stage Reverse Osmosis RO Purification Water System with DI Deionizing Mixed Bed Buy Amazon
4APEC Water Systems RO-CTOP APEC Water Systems RO-CTOP Portable Countertop Reverse Osmosis Water Filter SystemCarbon pre, sediment, MembraneBuy Amazon
5Express Water Express Water – Countertop Reverse Osmosis Water Filtration System Filter setBuy Amazon
6 OnliPure Zero Installation Purifier OnliPure Zero Installation Purifier Reverse Osmosis Countertop Water FilterFilter set, membraneBuy Amazon
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Luxy is a content writer who enjoys writing about water filtration technologies. She knows that water is a crucial part of our lives and it is important to make sure that we are drinking clean and healthy water. She developed this site in an effort to educate readers on the fundamentals of water treatment at home, at work, and when traveling. Also, the importance of clean, healthy drinking water for people in his community. When she's not working, she likes to spend time with her family and listen to music.

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