New Millennium Concepts Limited is the manufacturer of Black Berkey water purification elements. Their warranty statement is: "Black Berkey® purification elements have a two-year prorated warranty calculated in six months intervals. Our guarantee is prorated similar to the guarantee on tire tread. In other words, if you have used the filters for six months, 75% of the guarantee still applies and so you can get a replacement set for 25% of the normal cost."