I have always been particular as to what I put in my mouth!! I absolutely hate the sight of limescale floating in my nicely brewed peppermint tea. I tried the Tefal Quick Cup which 'boils' water on demand so to speak to save on energy. I use the word boil loosely as the water was never hot enough for a decent cuppa. I used to bung the cuppa into the microwave to heat it up a bit - so much for saving on energy there. And the limescale built up so quickly and could I get the special filter cartridges for it in the shops - no - I had to go searching online for them which usually cost more. I have always wanted to get a kettle that had a water filter cartridge within (I know... I need to get a life), but they either required a loan to be taken out to buy one or there just weren't any about. FINALLY a couple of months ago I found what I wanted and all with pretty colours too as an added bonus (so easily pleased aren't I). The Breville JK121 ticks all the boxes as far as I am concerned. I threw away my other water filter jug and now just use the kettle. Alright it still needs separate water filter cartridges - but if I look around carefully I can get them at discount prices - I buy a slack handful if I see them at a good price. The water can be left to keep warm by pressing the appropriate button and it all lights up red. Oh the joy to get a decent HOT cuppa. There's a filter gauge to let you know when the filter is getting less effective. The cartridge usually lasts about 4-6 weeks after having about 4 - 5 cups of tea a day - but that's just a very rough guide as I hadn't thought of counting. It's a big old thing and can be a bit heavy for fragile hands (I get the other half to put the kettle on most times so that's a problem solved!), so whizzing the kettle under the tap (can't fill up via the spout as the water has to go through the water filter) isn't easy if your sink isn't a decent depth or full of dishes to be washed, but that's a minor drawback. Just fill a jug up with water and tip in. Overall I am very happy that I am now getting a hot cuppa.