Product review (5 stars): Keep your family healthy
I checked my son's humidifier.  It was a disaster.  I don't know how he and his family survived without getting some horrible disease and destroying their lungs. (Who knows, maybe it just boosted their immunity.)  We not only replaced the filter but the entire humidifier. Now we all sleep better.
This is a good product, and we will try and replace the filter every year or two as needed.