I have one of these
Tefal Quick Cup - Hot and Cold Water in 3 Seconds: Amazon.co.uk: Kitchen & Home
It is noisy for the few seconds it takes to fill a mug, so if I have a brew in the night I use a normal kettle so as not to disturb the chap in the flat below.
I haven't bothered to change the water filter, because I have a filter system at my sink, so it only ever get filtered water put in it.