New Delhi, March 10 -- Contaminated water has made headlines across Indian cities with uncomfortable regularity over the past few years.

Delhi has seen repeated ammonia spikes in its municipal supply. Districts in West Bengal and Assam continue to deal with arsenic in groundwater. Parts of Rajasthan and Karnataka have reported elevated nitrate levels. Fluoride remains a concern across stretches of Telangana and Andhra Pradesh. And almost every monsoon, some city reports bacterial contamination following a pipeline breach or flooding event. The specific contaminant changes. The underlying problem doesn't.

India's water network is vast, and much of it is old. Pipes laid decades ago still run beneath cities that have since grown well past ...