Depends on how bad it is.
The biggest danger of severe diarrhea is fluid loss, but if it's not too bad it's quite possible to drink enough to compensate so that there won't be any immediate health risks.
In a longer setting, you might run into malnutrition issues, if food isn't staying in your system long enough to be absorbed. But if you have a good diet, even this will take some time to be serious.
A week if it is very bad.
If the water is untreated it can contain organisms that will cause diarrhea.
Yes they can, and if left untreated, can be fatal within a few days
Diarrhea is not a disease but a symptom of something else. Untreated it can cause death, especially in small children, due to dehydration.
Think "D". Dysentery produces diarrhea, dehydration and, ultimately, death (if left untreated).
One to two years is considered typical for untreated breast cancer. Once the cancer reaches stage 4 it is 1 to 2 months.
Dysentry is caused by a virus or some bacteria. It results in cramps and diarrhea. If untreated, it could kill you.
If galactosemia is untreated, high levels of galactose cause vomiting, diarrhea, lethargy, low blood sugar, brain damage, jaundice, liver enlargement, cataracts, susceptibility to infection, and death.
If a dog has diarrhea that is green with mucous it should be taken for medical treatment as soon as possible because something serious is wrong with the animal, and could result in death if untreated.
Without drugs, HIV usually converts to AIDS in about 10 to 15 years.
It takes about 10 years, if untreated, for Hep C to cause death in the person who has it.
Generally, a person will produce between 10-20 liters of diarrhea and vomit per day until death from dehydration.
Untreated glaucoma can cause blindness, but it's not itself directly fatal. Someone with glaucoma will live, on average, about as long as they would have if they'd gone blind from some other cause.