Not sure if the manufacturer would endorse it, but we've always found filling them with either cold water & bicarbonate of soda
or cold water & a small amount of baby bottle sterilising fluid does the trick.
But always give them at least 2 or 3 rinse outs with cold water. Then leave the lid off to air overnight. Also just use the MAPCO for hot water and have a decent thermos jug for the coffee or vice versa.
Or ...... let the F/A sort it
