Depending on where you are going and where you are staying, most well equipped hostels, guest houses, hotels and Couchsurfer hosts have microwaves and/or ovens, so you could sterilize your cup in the sterilizer with that.
If you are hiking and camping mostly, it is worth thinking of taking a little extra pan for your cup. It doesn’t need to be a big pot of course! If you get your hands on a kettle, you can use that and place your cup in a glass or the sterilizer and let boiling kettle water run over it a few times.
Another option is that you use sterilizing tablets, such as Milton sterilizing tablets.
We do not recommend to use plain alcohol to sterilize it as it might be too strong on the material. In case you go for it, make sure you rinse your Ruby Cup thoroughly before you insert it.
Please make sure that wherever you go your hands are clean before handling the Ruby Cup!