Product review (1 stars): Didn't believe it until it happened to me
What a horrible product! I thought that some of the negative reviews could have been a bad batch of filters. Well, that wasn't the case. I used the filter in the humidifier, rinsed it out before use, and in the morning, the water turned brown. It was awful. Not only was the water brown in the bottom of the humidifier, but the mist was brown too (saw the droplets on the stand).  Don't even bother with this product. AWFUL!