With today’s concerns over contaminants in household drinking water, a reverse osmosis water filter is a popular choice for many health conscious families. Not only do these filters take out substances that make your water taste and smell bad, they also can remove other contaminants that are a real threat to your health.
Reverse osmosis works by moving the water through a semi permeable membrane that has microscopic holes tiny enough for a molecule of water to pass through but too small for anything larger. Since water is comparatively a very small molecule, much of the contaminants are removed through this process.
A reverse osmosis filter will usually be used with a carbon or some other type of mechanical filter which will remove dirt and sediment and keep the fine membrane from clogging. As with any type of filter, the longer it is used, the more clogged it gets, and the less effective it will be; so the reverse osmosis filter must be changed periodically.
One problem with this method is that it can be rather slow, and it filters out a lot of the water – in fact almost 75% can be filtered out as waste water!
For this reason, it is typically not practical to use reverse osmosis as a whole house filtration system. Usually they are purchased as a unit that sits under the sink and treat only the drinking and cooking water. The unit contains a water storage container, reverse osmosis membrane, particle filters, carbon filter, and treated tap-water. One thing to keep in mind is that the unit will not treat the bacteria in water so don’t use any water that has unsafe levels of bacteria (regular tap water should be fine).
You’ll want to monitor your unit so that you know how effectively it is working and when filters need to be changed. Some units come with a device for this that makes monitoring easy. Otherwise, you should follow the directions as to how long before you replace the filters and perhaps even have your water tested periodically.
A reverse osmosis water filter system can cost over $3000; so, as you can imagine, the quality and effectiveness of each system varies widely. Plan to spend about $50 on replacement filters and over $100 when you need to replace the membrane.