My cat used to drink from the garden pond and never seemed to suffer any ill effects, and you often see dogs drinking from muddy puddles. So why do humans have to be so careful and only drink clean water?
• The simple answer is: we don’t. As a species, we survived many thousands of years drinking whatever water came to hand.
Many people throughout the world don’t have access to clean water, and have no problem most of the time. Of course, infections can spread through unclean water, so it is wise to be careful, but boiling the water or using a chemical treatment is usually…
