You folks use the term 'kettle' for hot water dispenser at hotels. At least here in the States, virtually all rooms now have 'single shot' machines instead: plain water for a cup of tea, or coffee with a pod/sachet/packet. I suppose a nasty guest could​​ make mischief in the small reservoir, but the odds are worse than a decent lottery win.

I can't believe they'd tell a Diamond guest 'No' upon request for an additional bottle or two of water on an extended stay. I'd probably reply: "Wow! Yours is a very cheap hotel!"