This filter should be changed at least every 12 months, or more often depending on use and tap water condition. We recommend replacing the O-ring when you replace the filter. Be sure to use the Dow Molykote 111 to lube the O-rings to get a proper seal and prevent leaks. We also suggest washing the housing in soapy water and then soaking in a solution using the Pro Sanitizer listed below. Fully rinse and insert the replacement filter, new o-ring and you are finished.