I understand. The reason why I asked is that I have had a similarly used non-cooling glass pitcher. If I don't wash it from the inside, then after a few months

I understand. The reason why I asked is that I have had a similarly used non-cooling glass pitcher. If I don't wash it from the inside, then after a few months it develops an invisible microbial slime layer inside which is not healthy. I can feel this layer by running my finger on the surface. Scrubbing and soap is required to eliminate the slime fully, preferably done once a month. I understand that the pot cannot be brushed. Using dish soap also may not make sense because it then takes a lot of water to fully rinse away the soap. When you run your finger on the inside, does it feel slimy at all? With a water bottle, the slime layer forms within weeks, not months, although a water bottle is different because it does touch the mouth. It is necessary to scrub and clean the water bottle every week from the inside, ideally with soap.