hot water tap is awesome. i use it the most for cleaning the portafilter after shots...though i do get a bit paranoid about the large quantities of steam running over my electronic control panel...sometimes i'll give it a good "blow" as I wash to keep the panel from getting engulfed by steam....even thought about installing a little fan to do it for me.

sometimes i'll run the tap water over dirty dishes that need a little help cleaning...i dont let any overflow go down the drip tray, just put a little bit on the dish and set it on the counter next to the sink to soak.

I use mine with each espresso I make as part of my pre-shot ritual. I fill the empty cup with hot water until the auto-refill is activated. That acomplishes two things. It pre-warms the cup and it prevents the auto-refill from activating mid-shot.

I would add that ideally, you would flush the boiler using water with very low minerals (i.e. RO water) then go back to your regular water. The amounts of hardness added when the machine fills up after steaming will not be drastic until the next flush.

anything to get out of descaling please! But i think this is not the topic of the thread...

I have a Zojirushi hot water dispenser I use for cup warming, Americanos, pourover, and tea. I find it much more pleasant than using the hot water tap on any machine that doesn't have a mix valve like the GS/3.