If you are suffering from the later stages of glotrot, drinking any substance has a chance of putrifying it. The putrification happens between the time you decide to drink and the liquid taking effect, so you get no forewarning against drinking putrified liquid.
Since the putrification happens to the entire container, the best way to avoid losing all your water to putrification is to pour each dram you want to drink into a separate container one at a time, so you don't risk the entire container each time you take a sip. You can also avoid ruining your water stores by eating watervine or another hydration-providing food instead of drinking.
Drinking putrescence reduces your satiation and hydration dramatically, but doesn't seem to be able to kill you directly.
Vomiting from overeating creates small amount (2 units) of putrescence under character's feet.