Water going 'off'

[EvianBaby]

I was awake for ages last night thinking about this. Can water go off, like food and other drinks do?

If you poured a glass of tap water and just left it sitting on the side for X amount of time, would it grow bacteria that would make you ill if you drank it?

[maclarencat]

Yes I think so . That why you get stagnant water ponds. I think it would be more likely with bottled water as tap water has chlorine and flouride in it (well in some areas) which kills bacteria.

[rojash]

Absolutely. This is also why, if re-using water bottles, you should also wash them thoroughly just as you would any other container.

[gingejbee]

Tap water contains virtually no bacteria and none which causes illness - so, if covered, would remain safe. Far safer than bottled water which has been partially drunk - this introduces bacteria from your mouth which then multiply - how quickly depending on temperature.

[EvianBaby]

Thanks for the answers. I've just realised I always use the same water bottle at work and wash it out rarely.

Oh well, I'm not dead yet. :)

[gingejbee]

...oh, and if the tap water is river-derived as opposed to underground sourced, it may well go slightly green because microscopic algae will grow in the light. However, still safe to drink.

[merejeans]

If you leave water in a kettle overnight, and then use it again next day, that doesn't taste too good, though probably safe. I usually water indoor plants with it, before filling afresh