What caused water contamination in Indore, India's cleanest city, that killed 7?

Indore, named India's cleanest city for the eighth straight time, saw at least seven deaths due to water contamination. According to officials, a leakage was found in the main water supply pipeline, over which a toilet was constructed. The waste from the toilet was diverted to a pit, and a faulty joint led to sewage getting mixed with water.