With more than 30 years’ experience in the residential and commercial water treatment space, Mark Nelson is a Class 1 Drinking-Water Operator and a CBWA (Canadian Bottled Water Association) Certified Plant Operator. As founder and president of Nelson Water in Ottawa, Mark focuses on dealing with challenging water treatment system designs for problem water. He also heads the largest water bottling plant in the city of Ottawa with a delivery network throughout the Valley.
In recent years, we have seen an increase in the interest in water filtration and the best processes to clean water efficiently. This is understandable, there are reasonable concerns about our water quality and we rely on water to stay fit and healthy. One of the lesser understood water cleaning processes is reverse osmosis or RO filtration. Although RO may sound like a complex term, it’s pretty easy to understand. In this article, we will explain how RO filtration works and how it may be a good fit for your home.
Do I Need RO Filtered Drinking Water?
If you receive your water from a water treatment plant, it’s all too easy to be complacent about water quality. Although public drinking water is cleaned to a basic standard, there are certain contaminants that are not removed. Another problem is the adding of chlorine based disinfectant to kill microorganisms in the water supply. This is a tried and tested method, but many people dislike the “swimming pool” odor of chlorine. In recent years, we have seen concerns about chlorine byproducts that may be harmful to health but further scientific study is needed. It’s important to understand that the water may be clean, but any break in the water delivery network can allow contaminants to enter after treatment. This is why boil notices occur when one or more contaminants are identified as a threat to public health. If you receive your water from a private well, you need regular testing and a reliable filtration system to make the water safe to drink.
How Does RO Filtration Work?
The first thing to understand is that RO is an entirely mechanical filtration process. There are no chemicals added to the water and the water is cleaned to a very high standard. But, this process takes time and for this reason, the cleaned RO water is stored in a tank for later use. This may seem inconvenient, but the tank is usually stored under the kitchen sink with a dedicated faucet for the RO water. So, it’s easy to use the water for drinking, cooking and amazing looking clear ice for your favorite beverage.
The basic principle behind RO filtration is to remove the unwanted contaminants and allow the pure water to pass through. This is tricky because the size of these contaminants can vary a great deal and for this reason it’s the smallest unwanted molecules that we need to worry about. At the heart of the RO filter system, there is a semi-permeable membrane with very tiny pores. These filtration pores can remove particles down to a size of 0.001 microns. To put this into some perspective, a standard carbon filter can only remove certain contaminants down to 1 micron. As you can see, RO filtration is extremely effective and it only allows pure H2O to pass through.
Moving sufficient volumes through these very tiny filtration pores would be extremely difficult under normal circumstances. So, the incoming water supply is placed under pressure and then forced through the filter to strip the contaminants away. Essentially, the water is being transformed from a less concentrated solution into a concentrated water solution. This movement creates reverse osmotic pressure which can remove a wide variety of contaminants, including: salt, dirt, sediment, chlorine, chloramine (chlorine mixed with ammonia), microorganisms, and more. The water is cleaned at the molecular level which is extremely clean and safe to use.
What Happens to the Contaminants?
The contaminants that are removed from the water as it undergoes RO filtration are left behind on the surface of the semi-permeable filter. This creates another problem because as the pores become clogged the RO filter will lose efficiency. Less water can be forced through and the process may take much longer to create sufficient volumes. This problem is solved with periodic flushing of the RO filter surface to remove the contaminants into the drain and out of your home.
Is RO Drinking Water Harmful?
No, some people find RO drinking water to be bland tasting because all the minerals have been removed. What we tend to think of as the taste of water is the dissolved mineral content that has been added after the water fell as rain. Water is an effective solvent and it dissolves many materials that it comes into contact with on its journey to your home. In terms of health, there are no risks, but you won’t get any essential vitamins or minerals from RO water. But, in reality any beneficial vitamins and minerals should be sourced from food because plants convert inorganic minerals into organic minerals easily. So, if you switch to RO drinking water, it’s important to eat healthily and take supplements as needed to ensure that your body is getting proper nutrition.
What are the Four Stages of Filtration?
The RO filter is not installed in isolation, there are usually four separate stages of filtration to make the water clean, healthy and more pleasant to use. These four filter stages are typically configured with a sediment filter, a pre-carbon block, the RO filtration membrane and finally a post-carbon filter. The sediment filter removes larger particles of sediment that may damage the entire filter system. The pre-carbon filter block uses activated carbon to remove contaminants as small as spec of flour to improve the RO membrane efficiency. We’ve already discussed the RO filter membrane at length, but to summarize it removes any molecules that are heavier than water. The final post-carbon filter block is present to add a little taste and to give the water a final polish.
In Conclusion
RO filtration can remove up to 99.9% of sediments and contaminants. This creates water that is exceptionally clean, but some trace volumes of beneficial nutrients can be removed. As we mentioned earlier, these nutrients are better sourced from food and supplements because the uptake is easier. Both public water supplies and private wells will benefit from RO filtration because it removes a wide variety of contaminants.
If you’re interested in a RO filtration system for your home, contact your local water treatment specialist today.