If the water everywhere contained arsenic, the whole population would have demised by now! Arsenic is only present in certain araes, mostly around certain rural ones with dilapidated tube wells. Untampered water bottles, as aforementioned are absolutely fine! They even taste much better than the chlorine filled, suffocating odour of certain taps of Essex;-)
You will have the tea as a consolation present...after watching England lose;-)