RO vs. Carbon Water Filters
At a Glance
A carbon filter improves the taste of tap water and offers basic protection from heavy metals, chemicals and bacteria at a low cost. If you have higher requirements for purity or live in a rural area without municipal water, consider investing in a more expensive RO filter instead.
Drinking tap water rather than bottled water reduces landfill waste and lowers household expenses. However, there are potential problems associated with tap water. Municipal water systems aren’t responsible for water once it enters your home, and metal can leech from old pipes. In rural areas, pesticides and sewage can contaminate wells and ground water. In either case, a filter can improve the taste and safety of your tap water. In this comparison of reverse osmosis (RO) vs. carbon water filters, we’ll examine the strengths and weaknesses of the two most popular filter types.
RO systems work under the principle of reverse osmosis using a semipermeable membrane. Under high pressure, water is pushed through a membrane with openings so small that only pure water is allowed through. Carbon filters work under the principle of adsorption using activated carbon, which draws impurities out as the water passes through.
RO filters are so effective in removing contaminants from water that they can also remove the healthy minerals you want to consume. For this reason, some owners of RO filters take mineral supplements or install remineralization stages in their household filters. By adding a remineralization stage to your RO filter, you can add desirable minerals to your filtered water, raising the pH and improving the taste. The pores in an RO filter may be as small as one nanometer, allowing it to remove contaminants up to 5,000 times smaller than those removed by an activated carbon water filter. Carbon filters primarily improve the taste of water and remove unpleasant odors. In addition, carbon filters can remove heavy metals and over 99 percent of most common bacterial pathogens.
Although an RO filter generally has a higher upfront cost than a carbon filter, RO filters may cost less in the long run because they can last as long as two years before they need to be replaced. You’ll need to replace a carbon filter about four times per year. With both types of filters, it is important to perform filter maintenance or check the quality if your water whenever you detect a change in water pressure or quality. If you use a carbon filter, always replace it according to the manufacturer’s recommendations as an old filter can harbor dangerous bacteria.
While a basic carbon water filter can be purchased for under $25, RO filters can often cost $200 or more. Features that can increase the cost of RO filters include membranes with smaller pores and extra filter stages that add minerals or increase pH. In addition, it can be more challenging to install RO filters as they need to be mounted under the sink or at the point where water enters the home. In inexpensive carbon filter mounts easily to most faucets.