Product review (5 stars): Replace it every year.
Filters are funny, if they are fresh, they perform well but if they are past their rated capacity, they can give you problems. This one is rated for 300 gallons. I change it every year or when the refrigerator filter light indicates to change, whichever comes first. I write the Installed Date on the back with permanent marker so I can refer to it if there is a question. Very heavy duty. Easy to install. Look for best pricing as they can be pricy.