The water that comes out of your kitchen tap may look clean, but it could also contain all kinds of contaminants. Dozens of systems are available to help you filter that water to make it cleaner and safer, but which ones are the best?

To help consumers make the best buying decisions, the Environmental Working Group (EWG) today released a new online guide to water filters. The buying guide ranks filters by price and effectiveness as well as the ability to either remove specific contaminants or soften hard water. Users can also modify results by types of filters, such as pitchers or devices that mount directly onto faucets.

"Having clean and safe drinking water isn’t a privilege, it’s a right," EWG research analyst Paul Pestano said in a prepared release about the new buying guide. "However, in the real world much of America's drinking water contains various contaminants. These can be reduced by investing in the appropriate filtration system."

According to the EWG's rankings, the most effective systems use what is known as reverse osmosis technology, which employs a special membrane to remove all kinds of contaminants. Carbon filters usually offer the best cost, but according to EWG carbon system do not remove many inorganic pollutants such as arsenic.

Visit the EWG's buying guide to try to find the best systems for your home. Search results typically link to online purchasing options. The guide also contains information on keeping your systems working at top capacity.

Also on MNN: