If you’re looking to effectively filter your local municipal water directly from your kitchen tap, research shows that the best option is a under-counter install reverse osmosis filter system combined with an activated carbon component. Below are a few things to note when considering this style of filtration system, and further, our 10 choices for under-counter 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 filter systems work by pushing water through a semi-permeable membrane that blocks anything large than a water molecule. This system removes inorganic pollutants, but alone, cannot effectively remove chlorine, trihalomethane, or VOC’s. This is why the best RO system includes an activated carbon component to remove all of the above contaminants, and up to 99-percent of total dissolved solids (TDS) from your water supply.
RO filters are wasteful, using 3 to 20 times more water than they produce. The key is to look for 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, carbon filter, cartridge filter, and membrane filter.
A 2-stage filter will remove the full scope of contaminants mentioned in bullets 1 and 2 except for fluoride. This is why a 3-stage or higher filter is what to look for if you’d like to remove fluoride from your water as well.
Because many minerals are removed in the process, some RO filters include or offer the option of purchasing an alkaline re-mineralizer to re-introduce 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 per year.