Experts say there is actually a tipping point at which it is better for your health to dump that glass of water and start afresh. Microbiologist Jason Tetro, aka The Germ Guy, also said 12 hours was the limit for drinking leftover water in glasses. One study found that bacterial cell concentrations in drinking water increase overnight. Infrequently used drinking water taps can also harbour high levels of bacteria. “After those 12 hours, there will be food for the bacteria to multiply.”In other words, if you drink water from the night before, you’re likely fine.
