How do I clean the water reservoir and drip tray?

Wipe the inside of the water reservoir and underside of the lid with a damp, non-abrasive, lint-free cloth, and allow it to air dry completely — do not dry the inside with a cloth as lint may remain. The drip tray should be lifted off the base carefully (keeping it level to avoid spilling), then rinsed and cleaned with a damp, soapy, lint-free, non-abrasive cloth. Both parts are hand wash only and are not dishwasher safe. (Pages 3–4)

From the official Keurig K-Express Essentials Coffee Maker manual, page 3

Have a follow-up question?

Answers from the official manual.

Common questions