Microwave and hot water

[BCL]

I know there's been talk about possibly using something like a mug heating plate or even an immersion heater. I wouldn't recommend either.

 

[dlagrua]

I usually drink Chamomile herb tea before bedtime. Since we are most often traveling in a sleeper, I pour the bottled water in a paper cup (that we take along) and use a 500W immersion heater to boil it. You can buy a good one for about $10. Works every time. The only thing to be careful of is to always keep the heater immersed in the water while its energized and not use a heater rated for too much wattage (as you might blow the breaker). On occasion I have even used the faucet cold water without problems. As long as you boil it you should be OK.