A story I just read made me feel thankful that my inadvertent sip of tap water in Kolkata ended up an uneventful slip-up.
More than 5,000 companies hold licenses from the Bureau of Indian Standards to produce drinking water, with consumption growing by an average of 22 percent annually — and five companies accounting for two-thirds of market share.
A 2003 study (pdf) by the Delhi-based Centre for Science and Environment (CSE) found found pesticides in many of them. It collected bottles of 17 brands, including the top five—Bisleri, Bailley, Pure Life, Aquafina, and Kinley—sold in Delhi. On testing, it found pesticides residues in these samples above the limit set by the BIS.
Be safe out there.