I think the real solution to your problem is a water softener. If you are having scaling problems in your coffee maker, you are likely also having scaling problems in your faucets, pipes, and other fixtures.
I have always had hard water where ever I lived, and the cost of replacing appliances and fixtures is far more than the initial cost of operating cost of a good water softener. A properly spec'd softener should not use more than 1 bag of salt per month. In my case, our water has 785ppm of TDS which is absurdly high. I have a 2.5 cubic foot 10% cross linked resin tank with a 1" port Fleck valve unit. In Canada I paid $2,500 for it, and I use about 1 - 1.5 20kg bags per month and I have incredibly soft water as a result - and that's with 5 ladies in the house. When I first bought this house, I had to replace all the faucets throughout, because they were calcified beyond repair. In year's passed when I didn't have a softener, I was replacing our coffee maker almost every 3 months and a new faucet would start showing signs of bad spray patterns within a few weeks.
Hard water can also be bad for your health: it causes gall and kidney stones, and bone spurs. The negative effects of softened water (via ion exchange) is the sodium content in the water, however, most experts agree that the amount is too low to impact health, even for those who are on low-sodium diets.
Beware water softener salesmen, they will often sell you a system that is poorly spec'd for your usage and circumstances. I fell prey to this several times. In my last house my water had a 3rd the TDS that this one does, but this time I did my research, spec'd out my own system, and now I use less salt and have softer water.
. . . just my two sense.