What is a Reverse Osmosis System and How Does it Work?

Widely considered one of the most effective water filtration methods, reverse osmosis (RO) creates clean, great-tasting water. RO systems are used in a variety of applications, including filtration for whole houses, faucets, aquariums, and restaurants. No matter what kind of water you start out with, there is likely an RO system that will suit your needs. Below you will find what reverse osmosis systems are, how they are beneficial, and what they are used for. You can also find a list of the best reverse osmosis systems on the market.

What is reverse osmosis?

Reverse osmosis removes contaminants from unfiltered water, or feed water, when pressure forces it through a semipermeable membrane. Water flows from the more concentrated side (more contaminants) of the RO membrane to the less concentrated side (fewer contaminants) to provide clean drinking water. The fresh water produced is called the permeate. The concentrated water left over is called the waste or brine.

semipermeable membrane has small pores that block contaminants but allow water molecules to flow through. In osmosis, water becomes more concentrated as it passes through the membrane to obtain equilibrium on both sides. Reverse osmosis, however, blocks contaminants from entering the less concentrated side of the membrane. For example, when pressure is applied to a volume of saltwater during reverse osmosis, the salt is left behind and only clean water flows through. 

How does a reverse osmosis system work?

 reverse osmosis system removes sediment and chlorine from water with a prefilter before it forces water through a semipermeable membrane to remove dissolved solids. After water exits the RO membrane, it passes through a postfilter to polish the drinking water before it enters a dedicated faucet. Reverse osmosis systems have various stages depending on their number of prefilters and postfilters. 

What does a reverse osmosis system remove?

A reverse osmosis system removes dissolved solids like arsenic and fluoride through the RO membrane. An RO system also includes sediment and carbon filtration for a broad spectrum of reduction. The carbon filters in an RO system remove chlorine and bad taste and odors, and the sediment filter removes dirt and debris

Does a reverse osmosis system remove…

  • Fluoride? Yes.
  • Salt? Yes.
  • Sediment? Yes.
  • Chlorine? Yes.
  • Arsenic? Yes.
  • VOCs? Yes.
  • Herbicides and pesticides? Yes.
  • Many other contaminants? Yes. The contaminants listed are some of the most popular ones treated with an RO system, but the system also removes a slew of other contaminants.
  • Bacteria and Viruses? No. If your water comes from a city treatment plant, then it should already be microbiologically safe. Reverse osmosis may remove some bacteria, but bacteria could grow on the membrane and potentially enter your water supply. To remove living organisms and viruses, we recommend UV disinfection

Reverse osmosis system benefits

A reverse osmosis system is one of the most extensive methods of filtration. It removes 98% of dissolved solids, which makes it healthier to drink. A water distiller is the only other drinking water system that also reduces TDS, but it's less efficient than an RO system. 

  • Harmful dissolved contaminants reduced
  • Sodium reduced 
  • Bad tastes and odors reduced
  • More environmentally friendly than bottled water
  • Easy to install and maintain
  • Fits under the kitchen sink

Is reverse osmosis good for the environment?

When the water you use drains from your home, chemicals and other contaminants must be removed before it's recycled. Wastewater is either sent to a water treatment plant and diluted to make it easier to treat or to riverbeds for nature to filter through the hydrologic cycle.

A reverse osmosis system makes waste treatment more efficient. Reverse osmosis water drained from your home is already free of chemicals since they've been removed in the carbon filtration stage. The leftover brine water has just a slightly higher concentration of dissolved inorganics. RO systems speed up the recycling process because no new chemicals are introduced into the water supply after RO water drains from your house.

Is reverse osmosis water good for you?

A reverse osmosis water system removes dissolved contaminants that you can't see but that could make you sick. Reverse osmosis does work for your kidneys by filtering water before it enters your body. It also removes beneficial minerals like calcium and magnesium from water, but that does not make reverse osmosis water bad for you.

Our bodies are 70-80% water that hydrates, lubricates joints, and aids organ function. You don’t need minerals to do those things. You would have to drink excessive amounts of water for your body to absorb enough mineral content to make a significant difference. Food is the primary source of essential nutrients, not water. If you want more minerals, eat your fruits and veggies.

Some mineral content is fine to drink, but the EPA recommends that the amount of TDS in water not exceed 500 parts per million. A large portion of the U.S. has TDS levels that exceed this level and could benefit from an RO system.


Posted by John Woodard on February 12, 2022

Back to blog