A person was using water supplied by Municipality. Due to shortage of water he started using underground water. He felt laxative effect. What could be the cause?

Laxative effect is the effect caused by laxative substances that loosen stools and increases bowel movement. High doses of laxatives may even cause diarrhea.

Study on it reported that the presence of excessive sulphate (greater than 500 ppm) in the drinkingwater is the major cause of it. When sulphate is present in moderate amounts it is harmless.