WATER QUALITYWhat is a Reverse Osmosis Filter?

March 7, 2022

Reverse osmosis will give you clean water which is perfect and healthy for drinking. Reverse osmosis, or RO, is one of the best, most efficient water filtration modes, including for home use.  RO systems are great for many applications, including home kitchens, faucets, fish tanks and restaurants. Regardless of the water you start out with, there is likely a reverse osmosis filter system to fit your requirements. We’ll help you know more about reverse osmosis and reverse osmosis filters.

What is reverse osmosis?

Reverse osmosis removes pollutants from water. The water pressure sends the water flow through a semipermeable membrane filter. Water passes through the membrane creating clean, fresh water called permeate. The water left on the contaminant side is called brine or waste.

It’s called osmosis because water ends up being more concentrated as it goes to the clean side of the membrane until it’s equal pressure on both sides. Reverse osmosis means it’s filtering out contaminants from getting to the clean side of the membrane. For example, when salt water runs through a reverse osmosis filter system, the salt and some water is left behind and clean water passes through the system.

How does a reverse osmosis system work?

A reverse osmosis system eliminates sediment, minerals, chemicals, fluoride, chlorine and other matter from water. It usually has prefilters, then a semipermeable membrane which water runs through. There may be a final filter specifically for drinking water after the membrane filter. Reverse osmosis systems have numerous phases depending upon the design and purpose of the system.

Steps in a Reverse Osmosis System

An RO system typically has 3-5 stages of filtering. A RO’s filter system should have a sediment filter and a carbon filter. These filters can be before or af

What is a Reverse Osmosis Filter?
Reverse osmosis systems have numerous phases depending upon the design and purpose of the system.

ter the membrane filter.

A sediment filter filters particles such as rust, dust and dirt – basically larger stuff in water. Carbon filters filter out material such as chlorine and volatile organic compounds. Carbon filters do the most for odor and taste of water. The semi-permeable membrane filter removes 99% of total dissolved solids. Some systems have carbon filters before and after the membrane filter.

RO Steps:

  1. When water enters an RO system, it goes through prefiltration. Prefiltration usually consists of a carbon filter and a sediment filter to remove larger particles which could harm or wear the membrane filter.
  2. Water passes through the semi-permeable membrane filter. Dissolved fragments or solids, now mostly too little to be seen with an electron microscope, are filtered out.
  3. There could be another filtering stage here. After filtering, water goes into a tank until it’s used. A reverse osmosis system will filter water until the tank is full, then it will stop.
  4. When you turn on a faucet or fixture, water comes from the tank. There could be another filter, such as a carbon filter for drinking water, between the tank and your faucet.

What does a reverse osmosis system get rid of?

A reverse osmosis system filters out sediment, chlorine, debris, dirt, fluoride, salt, arsenic, VOCs, herbicides and chemicals. Removing these pollutants, contaminants and matter typically improves the taste and smell of water a great deal.

An RO system will not necessarily remove bacteria and viruses from water. If your water comes from a public treatment plant, it should already be microbiologically risk-free. Reverse osmosis may eliminate some microorganisms, but it isn’t guaranteed to filter a certain percentage of bacteria. To get rid of bacteria and viruses, the best option is UV disinfection.

Pros of RO Water

  • Reverse osmosis filters the most contaminants

RO is the one of the most effective ways to eliminate the most contaminants from water. The EPA says reverse osmosis is, “effective in eliminating all disease-causing organisms and most chemical contaminants.”

  • Reverse osmosis is good for the environment

You’ll reduce how many plastic bottles you and your family use. One, you’ll be reducing how much plastic waste you go through and filtered water, without being in a plastic bottle, may be safer for you along with being greener.

  • Reverse osmosis gives you better water for cooking

Many restaurants have started using RO for washing ingredients and cooking. It improves the taste of their food. While the benefits of RO are making it a professional standard, you can use the same system to give your home cooking better safety and taste.

Cons of RO Water

So while reverse osmosis is the most effective type of water filtration on the market – stopping particles as small as fluoride from staying in your water – RO can be inefficient and have disadvantages you might want to consider.

  • More water used, higher bills

According to the U.S. Environmental Protection Agency, reverse osmosis systems use about three times as much water as they put out. Most of the water ends up as waste or brine. This will show up on the water bill. In fact, some home RO systems wind up using, on the clean filtered end of the system, about 5-15% of water.

  • Lower water pressure

Some people who use reverse osmosis filters then have decreased water pressure at different points around their house.

  • Disposal of brine or waste water

Homes with RO systems must have a disposal system for the brine or waste water. Depending on your home and geography, you can dispose waste water into the sea, but in the major majority of cases, you can consider an evaporation system to avoid runoff or groundwater contamination, as it can be bad for the environment or nearby ecosystem.


South End Water Filtration specializes in HALO Water Filter products including the HALO H2 Zero Whole Home Water Filter. We’re just a click away to help and answer any questions. South End Plumbing and South End Water Filtration will give you a free estimate. Call us at 704-486-1988 or contact us online to schedule a visit.