What the best water filter has
- A large enough capacity. Pitcher water filters are very affordable and easy to use, but their capacity is so limited that they're best for just keeping a basic supply of drinking water on hand. The amount that you or your family drink every day will influence the size pitcher you need, and you need to be sure a larger pitcher fits in your refrigerator. Countertop, faucet-mounted and under-sink water filters give you an unlimited amount of filtered water, and have the added convenience of letting you toggle between filtered and tap water.
- The proper filtering mechanism. Most water filters use carbon, which absorbs impurities and odor as the water passes through the porous material. Multistage filters can remove contaminants such as lead, chlorine, parasites, pharmaceuticals, bacteria and harmful chemicals, and the semi-permeable membranes of reverse osmosis systems flush the highest percentage of contaminants away.
- A moderate to fast flow rate. Most water filters will noticeably slow your flow rate, but a unit becomes inconvenient if it takes too long to do its job. Flow speed varies depending on the type of water filter. Some water filters also slow down as the filter gets toward the end of its useful life; a filter change should fix that.
- Certifications backing up contaminant removal claims. Manufacturers may test their own products, but a water filter isn't certified to remove contaminants unless it has been tested by an independent organization like NSF International or the Water Quality Association. Both have databases that consumers can easily search to learn more about the effectiveness of specific models.
- A filter change indicator. Water filters that measures how much water you have used and then alert you with an indicator is the most accurate way to determine if your filter needs to be replaced. Other units may include timers or stickers to count remind you after a certain period of time, usually 3 to 6 months.
- Compatible attachments. For installed filters, the best systems are compatible with a wide range of faucets, sinks and plumbing. Occasionally, consumers may need to purchase different faucet adapters or accessories like extension hoses or icemaker hookups to make a filter more usable. Some water filters have faucets available in a variety of finishes to match your existing décor.
- Long warranty. A 90-day warranty may be suitable for a pitcher filter, but a longer warranty of one or two years is best for any filter that requires installation.
Know before you go
What contaminants affect your drinking water? Not all water is the same, and it's important to know what contaminants are present in the drinking water in your area. This will help you determine whether you need only a basic filter to improve taste or a sophisticated system that reduces pollutants and parasites. More information on your local water supply and how to find a state-certified tester can be found at the United States Environmental Protection Agency website. Once you pinpoint your specific water concerns, you can identify the best water filters for your needs.
How much water do you want to filter? If you need filtered water just for drinking, a pitcher may suffice. Cooks will find faucet-mount, countertop and under-sink filters more convenient as they won't need to continuously refill a carafe.
How permanent do you want the water filter to be? Pitcher, countertop or faucet-mounted water filters are likely the best option for dorm residents or renters who can't make permanent modifications to their living spaces. Under-sink water filters are permanent and may require you to drill a hole for the filter faucet. These may require a certain level of expertise to install, which could necessitate hiring a plumbing professional.
Consider annual cost and maintenance requirements. Water-filtering pitchers and faucet-mounted filters aren't that expensive, but the cost of replacement filters will quickly outpace the initial purchase price. Use the cost of replacement filters and manufacturer recommendations on filter life to estimate your annual expenses. Cleaning, battery replacement and new semi-permeable membranes are additional charges for reverse osmosis systems. Also, consider the cost of discarded waste water if your supply is limited or you have high municipal water rates.