Insinkerator filters don’t stop the limescale, even when changed every 6 months, so the cheap tap valves fur up after 3-4 years. The cheap plastic valves are very hard to extract from the tap, so we have to pay £300 every 3-4 years for a new tap assembly. It’s simply a poor design. Then there are the 3-4 year tank splits. Best avoided after 4 tanks and 3 replacement tap assemblies.