With every passing year we learn more about what is in our water and the effects those contaminants can have on our health. Contaminants in residential drinking water can include almost anything, from industrial waste that was dumped in a river, to fertilizers and household cleaning products. Many times, treatment involves adding a chemical to the water to neutralize the contaminant—for instance, chlorine is added to water to control the amount of microbes—but these chemicals can give water undesirable tastes or odours. Technology like reverse osmosis systems exists to remove contaminants from water without adding any chemicals.
Reverse osmosis (RO) systems are becoming an increasingly important, needed appliance in our homes. RO systems utilize your water pressure and a semi-permeable membrane to reduce contaminants for great-tasting water without adding any chemicals. They are typically used to purify drinking water which is where contaminant levels matter the most. Some areas, however, have such terrible water that an RO system is used for the entire home.
Every reverse osmosis system has at least four parts: a prefilter, an RO membrane, a storage tank and a postfilter. Water supplied by the city or a well enters the system through the prefilter, which protects and extends the life of membrane by filtering out the things that can harm it, like chlorine and sediment.
A reverse osmosis membrane uses a semi-permeable membrane to separate water molecules from other molecules. “Semi-permeable” means that some things can pass through and others can’t. A familiar example would be your furnace’s air filter, although, semi-permeable membranes for water treatment allow passage based on the size of the particle as well its molecular charge whereas typical air filters separate the contaminants exclusively by size. Holes or pores in the membrane are sized just big enough for the passage of a water molecule—even small contaminants such as tobacco smoke or paint pigments are too big to go through an RO membrane. At this point, because the membrane only lets certain molecules pass through, there is some waste liquid with a highly concentrated amount of contaminants that goes to the drain. The virtually contaminant-free water that makes it through the membrane, called a permeate stream, is safe to drink and tastes great.