“We have used a British Berkefeld (also known as “Berkey”) filter for many years. These use four ceramic filter elements which last a long time and work very well.”
If you ran it full out 8 hours a day producing clean water, what is a “long time?”
Before we switched over to distilling our own water, we used it every day for about 8 years. When we put it in storage, the filters were/are still quite usable and ready for backup filtration when needed (for example, in a power failure). I think the filters themselves are rated to last for many thousands of gallons.