eli5: water degradation


If I would fill a bucket with tap water would the water stay fresh longer if I sealed it? What makes the water go bad? And if it’s bacteria (aerobic/anaerobic), why is one type worse for the water quality?

In: Biology

Carbon dioxide in the air goes into solution and makes the water slightly more acidic. This extra acid is what gives what we call stale or flat water the sour taste. It’s still perfectly safe. We deliberately put CO2 into water to make soda or seltzer but in the case of soda there’s a fuckton of sugar or something sweet to overpower the sour taste. There’s no really way to get around it apart from aerating the water somehow. The turbulence will get the CO2 out of the solution and displace it with oxygen.

Water can’t go bad as it were. Food goes bad because the chemicals in food are consumed by microbes and often turns the food toxic. Exceptions like cheese exist but those are rare as even reactions we want like brewing result in toxic chemicals like ethanol to form. If you have a container of pure water it will never go bad. That said if there is sugar in it or minerals in it those can be used by microbes to form the hazardous chemicals but the water itself is fine where something like a steak wouldn’t be. You can distill even the most nasty water and drink it just fine with very few exceptions.