If you suffer with limescale... buy it now.
We have had horrendous limescale since we moved in to our house 7 years ago. We have a glass kettle and have had to descale it weekly, even though we britta filter the water before it goes in.
We had a nocalc filter fitted, and immediately it wasn't good. I emailed the company after 3 days complaining that the water poured clear but after a few minutes of standing it was cloudy with sediment in it. It was explained to me that this may be because its breaking down the limescale in the taps, and that I should give it a few more days.
A few days later, and they were right.
Our water is now perfectly clear, it tastes so much better (our gerbils are drinking so much more water now), and we have not had to descale our kettle since we installed it.
Would definitely recommend to anyone in a hard water area.