In other words, if you drink water from the night before, you’re likely fine. But if the water has been sitting for a whole day, it’s better to get a new glass of water, even if you used a water filter, Tetro said, or you risk suffering from gastrointestinal issues.
Article source: https://www.huffingtonpost.co.uk/entry/drinking-days-old-water-health-impact_uk_69bbe2a3e4b04fe25a48e9a5