By Sarah Burns on March 11, 2010 in
For the most part, point-of-use systems use carbon filters to absorb impurities. A reverse osmosis system, one type of under-sink water filter, also possesses more aggressive filtering materials in the form of semi-permeable membranes. These can easily remove nitrates, arsenic and other more harmful contaminants that carbon filters alone cannot. Point-of-entry systems, on the other hand, work to filter an entire household's water supply. These are usually installed outside or in basements and are used for stopping visible contaminants such as sediment and rust.
While the type of water filter you choose is important, the cost and availability of its replacement filters is a key consideration. Poorly-made filters can wear out and break easily, thus requiring more frequent replacement and increasing the cost of ownership. To head off problems, when you're shopping for a water filtration system, be sure to compare manufacturers' recommended filter-replacement intervals when estimating your total maintenance costs. This is a case in which owner-written user reviews can be helpful in substantiating manufacturers' filter-life claims. Our updated report on kitchen water filters goes into these matters in greater detail and calls out the best-reviewed pitcher, faucet-mount, and under-sink water filters.