Look inside you kettle! See why! Here a kettle lasts 6 months if that!
pyropetepete said:You've flux, bits of solder, copper, swarf, paint that are all in there and when wet or soaked over time will become free. This stops that blocking the fins in your cpu block or gpu etc etc
You will not get ANY limescale in a rad with tap water if all you are doing is flushing it with cold water for 10 minutes, and espcially if you do a final flush with deinnized afterwards if you are extra paranoid.
All of this crud will go down the plughole along with the tap water whilst flushing it, there is simply no need for a filter, unless you like to collect the bits to look at afterwards. Which if you do use a tea strainer or something over the tube going to the plughole.