Bottled water is another scam though! Yes, use the hot water tap. But, doesn't Hoffman's French press method require near-boiling water? A hot water tap is typically maybe 60C at most.
Here's the type of heater I was thinking of: https://www.ebay.com/itm/311442084287
That's a US version (120V) but I'm sure they have 230V ones if you need that. Another idea is a camp stove.