If you are looking to effectively filter your local municipal water directly from your kitchen faucet, research shows that the best option is an over-the-counter reverse osmosis filter system combined with an activated carbon component. Below are a few things to note when considering this type of filtration system, and in addition, our 10 choices for countertop reverse osmosis (RO) systems.
Activated carbon filters (such as Brita), when used alone, filter a range of contaminants but do not filter inorganic pollutants such as fluoride, arsenic, nitrate, hexavalent, chromium and perchlorate.
Reverse osmosis filtration systems work by pushing water through a semi-permeable membrane that blocks everything that is large than a molecule of water. This system removes inorganic pollutants, but alone cannot effectively remove chlorine, trihalomethane or VOCs. This is why the best RO system includes an active carbon component to remove all of the above contaminants and up to 99% of the total dissolved solids (TDS) from your water supply.
RO filters are wasteful, using 3 to 20 times more water than they produce. The main thing is to find an RO system with the least amount of wastewater.
There are between 2 and 6 stages of filtration options for an RO system. Filters include a sand filter, a carbon filter, a cartridge filter and a membrane filter.
A 2-stage filter will remove all of the contaminants mentioned in bullets 1 and 2, except for fluoride. This is why a filter with 3 or more stages is what to look for if you also want to remove fluoride from your water.
Since many minerals are removed during the process, some RO filters include or offer the option of purchasing an alkaline remineralizer to reintroduce beneficial minerals such as calcium and magnesium and balance the pH of the water.
Once installed, an RO filter system is relatively low maintenance with the need to change its filters about once a year.
N.B .: For a more complete reading on RO filtration, see the articles on Water Filter Magazine and Gimme the Good Stuff.