Mumbai has the best quality of tap water, Delhi ranks worst
According to a Bureau of Indian Standards (BIS) study, Mumbai has the best quality of tap water among capital cities in states where samples of tap water were tested. In Mumbai, all 10 samples of tap water passed the BIS test. Following Mumbai is Hyderabad, where only one sample failed. What's alarming is that the national capital Delhi has the worst quality tap water, where all 11 samples failed the BIS test.