After Anand Malligavad tumbled into a lake, he thought he might die ¡ª not from drowning, but from the stench.

Like hundreds of other lakes in the southern Indian city of Bengaluru, the one Malligavad suddenly found himself in was a receptacle for sewage, plastic debris and construction waste. His unplanned dip happened in 2017, when Malligavad, a mechanical engineer, was on a stroll with friends near his office.

Walking back home, he smelled so bad that a guard refused him entry into his own residential enclave. The next day, Malligavad made an unlikely pitch to his company: He would restore the 36-acre lake if it funded the project.