Calcutta’s sanitation heritage: a unique engineering legacy

The city of Calcutta (now Kolkata), a ‘crowning glory’ of the British Raj from 1757 to 1911, served as the administrative capital of continental India. Calcutta is situated by the River Hooghly, a tributary of the Ganges. Since its inception in 1690, it fundamentally resembled the urban setting of London. Over the past 300 years, Calcutta has witnessed phenomenal growth and is now considered one of the sprawling metropolises of the world. Triggered by its growth as a commercial hub in the early nineteenth century and prevailing insalubrious sanitary condition, planning of sanitation and drainage was initiated by Governor-General Lord Wellesley. The extremely unhygienic conditions of the city, filthy condition of its drains, high rates of disease propagation and sickness could be compared to the infamous ‘great stink’ of London in 1858. Several sanitation schemes were proposed for Calcutta but that of William Clark was adopted for construction in 1858, following extensive review by experts in India and the UK and despite being the most costly proposition. This paper documents the history behind the development of this combined drainage system, which still serves Calcutta in the new millennium, and is still relevant in the construction and renewal of sustainable sewerage networks.