The glass tube in the water reservoir is cloudy. May 05, 2021 18:48 Updated Your brewer may need to be descaled. Read our articles on what descaling is and how to descale for more information, or reference your instruction manual. Related articles How frequently should I descale and clean my brewer, and what should I use? Coffee is dripping down the side of my brewer. What is descaling? My coffee tastes weak or bitter. I’ve noticed an organic, “slimy” buildup in my Moccamaster’s water reservoir. What is it, and why is it happening? Comments 0 comments Article is closed for comments.