| If you want to compare drinking water systems, one | | | | treatment was the removal of disease-causing |
| of the first questions you'll ask is, "What does | | | | microbes in the water supply. What does reverse |
| reverse osmosis do, as opposed to a filtration | | | | osmosis do to these microbes? Again, it concentrates |
| system?" That is what you will learn in this article. I | | | | them in the untreated water. Once chlorine was |
| think once you have some answers, you'll start | | | | introduced as a disinfectant, this concern diminished. |
| asking, "Why would anyone choose a reverse | | | | Chlorine is very effective at destroying microbes, but |
| osmosis drinking water system?" | | | | is a carcinogenic contaminant that should itself be |
| So, what is reverse osmosis? Reverse osmosis is a | | | | removed from all drinking water before consumption. |
| physical process that is the opposite of osmosis. | | | | Chlorine molecules are not removed by the reverse |
| Osmosis occurs naturally in plants, where two fluids | | | | osmosis process. Neither are the carcinogenic |
| of different salinity are separated by a | | | | byproducts of chlorination, such as THMs ad HAAs. |
| semi-permeable membrane. Water in the less saline | | | | So how does filtration work that is different from |
| fluid will move through the membrane into the more | | | | reverse osmosis? Filtration works by passing water |
| saline fluid until the two have equal salinity. It turns | | | | through one or more filters. Some of the best |
| out if the more saline fluid is under pressure and the | | | | filtration systems have two types of filters: an |
| other fluid isn't, water will move from the more saline | | | | activated carbon filter that reacts with contaminants |
| fluid into the less saline fluid. So if you have seawater | | | | to remove them from the water, followed by an |
| on one side of the membrane and fresh water on | | | | extremely fine sub-micron filter that removes any |
| the other, and you apply pressure to the sea water, | | | | contaminant larger than the pore structure. These |
| you'll get more fresh water. This is an extremely | | | | types of filter systems effectively remove organic |
| useful process, and is a preferred method for | | | | chemical, microbes, heavy metals, chlorine and its |
| desalinization of seawater. | | | | byproducts. |
| Reverse osmosis is used to create 'purified water'. | | | | In considering reverse osmosis, you also need to ask |
| The idea is that the contaminants in tap water will | | | | "What does reverse osmosis do with trace essential |
| not get through the membrane, resulting in purified | | | | minerals in water?" |
| drinking water. The problem lies in the membrane. | | | | Another drawback to reverse osmosis is that it |
| The membrane allows water molecules to pass | | | | removes minerals from drinking water. These minerals |
| through, but blocks contaminants whose molecules | | | | are recognized by the World Heath Organization, as |
| are larger than water molecules, such as large organic | | | | well as many government agencies, as essential to |
| molecules and microbes. What does reverse osmosis | | | | human health. Filtration does not remove these |
| do with these contaminants? They remain on the | | | | minerals. |
| untreated water side of the membrane until the | | | | So when you choose a drinking water purification |
| water is removed and the system is flushed. That | | | | system, I hope you keep in mind that filtration |
| means that there is a large amount of highly | | | | systems are far more effective at removing chlorine |
| contaminated water waste associated with the | | | | and many other contaminants than reverse osmosis, |
| reverse osmosis process. | | | | without removing the minerals that contribute to |
| A century ago one of the concerns in water | | | | your continued good health. |