Product review (4 stars): Worth Switching Out at Least Once a Year
Amazon came in about $10-$15 less than the home improvement stores in the area, so I decided to get one after having the old one in for a few years. Definitely worth the switch because our water and our ice cubes actually taste better.  It will help us save on the cost of bottled water, too. Replacing every 6 months might be a bit much, but you probably shouldn't wait any longer than 1 year.