I am SO glad we live in a hard water area because of that sort of thing. To keep my coffee maker from being clogged with mineral deposits, back when I had an expensive one, I took to buying filtered water in refillable one-gallon jugs, and because I hate shopping, I keep six of them on the shelves below the coffee maker. (My coffee stand is a three-shelf foldup bookcase.)

In plumbing emergencies, and I've had a few, this stash means never having to go dry or thirsty. Jugs: ~$5-$6 @. Refills, ~$0.40. Water security - priceless.