Check the Bisphenol A, or BPA, content of the pitchers. This chemical found in plastic has been linked to numerous health risks. According to Consumer Reports, both ZeroWater and Brita claim their pitchers are BPA free, although they are not required by law to disclose that information.
Compare the contaminants the filters claim to remove against the Consumer Confidence Report you receive from your municipality. This report, usually mailed yearly, lists all contaminants found in your tap water. If your water comes from a private well, have it tested by a state-certified testing lab.
Compare the pitchers for fluoride removal if that's important to your family. ZeroWater pitchers remove fluoride, but Brita pitchers remove only a trace.
Choose a pitcher that has a convenient indicator to let you know when it's time to change the filter. Brita has an electronic calendar minder on some models, while ZeroWater provides a tester that indicates when it's time to change the filter.
Check to see how many gallons of water the filters can process before they need changing. Also compare the cost of replacement filters.
Compare the carafe shapes to select the one that holds the most water and will fit best in your refrigerator.
Compare the prices after considering all the features, to see which one is the best buy.