Built at a whopping cost of Rs 90 lakh, the facility will be of great help to the general public, including joggers and cyclists, who throng the iconic promenade, a civic official said.
People do not have to pay any fee to use it, he said.
Shiv Sena's youth wing leader Aditya Thackeray inaugurated the six-block toilet on Monday.
Leading alloy-maker JSW Group, Samatech Foundation, the social development arm of Samatech company, and the Nariman Point Churchgate Citizens Association came together to set up the facility.
A toilet generally requires eight litres of water for a single flush, but this facility uses only 800 ml water, an official of the JSW Group said.
"Besides saving water, the toilet's vacuum technology will prevent a few million litres of raw sewage from getting flushed directly into the Marine Drive bay each year," Samatech Foundation's co-founder Akshat Gupta said.