Do we have to change our water filter cartridges every 6 months?
No but we have to remind you every 6 months. We have to abide by the water treatment industy's "best practice"; as private citizens - you do not.
Nevertheless, you must change every 12 months or risk bacteria break through..
Our cartridges are longed lived (see cartridge life explained) and most people get far moe than 6 months life out of them.