This buildup can be attributed to different water sources and potential moisture trapped in the water reservoir. If you are in a warmer, more humid climate, you may experience this to a greater degree than if you are in a dryer, cooler climate. While this buildup occurs in all coffee makers, Moccamaster coffee brewers are unique in that you can see inside our components, helping you better understand when it’s time to clean your brewer. To remove all buildup, from coffee oils to organic matter, we recommend using Cleancaf Cleaning Powder or BioCaf Cleaning Powder by Urnex. These cleaners are non-toxic and biodegradable and can be used as frequently as needed to keep your brewer clean. Note that cleaning should not be confused with descaling, which is a process that removes limescale buildup from inside your brewer. Tip: to reduce ongoing organic buildup, leave your water reservoir’s lid slightly ajar after brewing to allow the reservoir to dry out completely between uses.