Technically Correct - Mander

Or just bring an empty bottle through and fill it up at the tap/water fountain?
Some people think tap water tastes bad
I wouldn’t drink tap water outside of continental Europe. Maybe the original OP is simply in a third world country like the US.

Outside of Continental Europe

Oddly specific when of the 10 countries judged to have the equal best tap water quality, 4 are European islands (UK, Ireland, Iceland, Malta) and many Continental European countries score behind the US:

worldpopulationreview.com/…/water-quality-by-coun…

Water Quality by Country 2025

I wouldn’t trust the plumbing in the UK. They do crazy two-faucet stuff.
That two tap stuff makes the cold water safe. Don’t drink from the hot tap where they don’t dare mix hot and cold