Kat, I've had one for 5 years and use somewhat hard water, so far no problems, but I only use it about 4 times a year. Also, I was using the 'old' cleaning solution that was recommended with my machine, which they no longer make. I am going to try the new cleaning solution for the first time this weekend. I hope it doesn't leave a film and cleans as well as the old one.
Filtered, bottled, or distilled water will work fine with this model. Hope this helps.