Yes, you can fill the bottle with hot water and make yourself a tea in it. A tip from the team: We even use the CARRYs as a teapot and hot water bottle at the same time  PLEASE NOTE: Glass does not like extreme temperature changes and can crack. To avoid thermal shock, pour the hot water into the bottle very slowly or pour in a little lukewarm water first and mix in the hot water. The lukewarm water also has the advantage that you can drink the tea more quickly and you can handle the bottle better because it does not get as hot.