Write the installation date on the cartridge. From this point onwards, the cartridge can be used for a maximum of six months or one season, and for up to 5,000 litres of water.
Signs that the filter needs changing may include changes in the taste of the water (e.g. due to chlorine) or cloudiness. Furthermore, the water pressure drops noticeably once the maximum permissible filter capacity has been reached.
In addition, a calendar reminder on your smartphone can alert you in good time when it is time to replace the filter cartridge.