What exactly is reverse osmosis?

10.26.25 01:44 PM - Comment(s) - By John

Reverse osmosis is one of the most effective forms of water treatment, and is readily available and affordable today.  But what exactly is reverse osmosis? Read on to find out what reverse osmosis is and what it can do for you.


Reverse osmosis is a mouthful to say, but it's pretty simple to understand once you understand the natural process of osmosis. In nature, when there are two solutions separated by a semipermeable membrane, the more concentrated solution will migrate to the solution with less concentration. This process is very important in biology since it guides the way water moves about in living things; for instance, it's the reason why there are distinctions between "freshwater" and "saltwater" fish and also how plants maintain their turgor. 


Reverse osmosis is just the process of osmosis in reverse. However, a key difference is that osmosis is passive; that is, done without external energy. Think of it like a ball rolling down a hill due to gravity. Performing this process in reverse means that highly concentrated water can become pure water on the other side of the membrane, but it will require energy greater than osmotic pressure. In the case of an undersink RO system, this external energy comes from your home's water pressure.

The stages of a typical undersink reverse osmosis system


1. Sediment filter
First, the water runs through a depth filter, which is usually a string (wound) filter or a meltblown (polypropylene) filter sized to 5 microns. This filter stops dirt, rust, and sand from getting into the system. 

2. Carbon filtration
After running through the depth filter, water is passed through one or two carbon blocks that remove chlorine and chloramines, as well as other contaminants that cause water to smell and taste bad.

3. Reverse osmosis membrane
The treated water is now ready for the heart of the system, the membrane. This semi permeable membrane allows water to pass through while routing dissolved solids like lead, arsenic, and many others into your home's sewer system. The resulting water has had 95-99% of its total dissolved solids (TDS) removed.

4. Water storage
Because the purifying process of undersink reverse osmosis is relatively slow, the cleaned water will usually be stored in a pressure tank so that fresh water can be accessed on demand.

5. Polishing/additional filtration
The clean water is run through a final polishing filter filled with granulated activated carbon (GAC) to ensure the water tastes fresh and is odor free. Some systems will also have additional filtration to add back minerals or otherwise further clarify/disinfect the product water.

Is reverse osmosis right for you?

If your water doesn't taste or smell good and your family can't stop buying bottled water, then an RO system is the product for you! Contact us today to find out which system best suits your needs!

John

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