The people of Mumbai have been assured by the BMC that even though the water is colored in several parts of the city, it is still safe for consumption.

The yellow coloration of water is caused due the abnormal levels of iron, magnesium and chlorine and prolonged intake of these elements can cause irritation in the stomach, and gastric problems.
Dr Abhay Chaudhary, director, Haffkine Institute, said "That the colour is (yellow to) green shows there could be other contaminants. These could be chemicals.I am not sure if the BMC subjected its samples to such tests."
Source-Medindia