Lal Dighi, Kolkata - main source of water in the early colonial days!!

Lal Dighi, Kolkata Panoramio
Above image: Lal Dighi (Kolkata,W. Bengal) - in the middle of Lal Bagh had been very much there as part of  small pocket of human habitation far before the arrival of East India company and its chief Job Charnock, who is purportedly called the founder of Calcutta (Kolkata). The Calcutta High Court ruling, a few years ago, pointed out that Job Charnock was not the founder of Calcutta as the town Kalighat had been in existence before his landing in Calcutta.........
In the heart of Kolkata, in the middle  of B.B.D Bagh (earlier known as Dalhousie Square), West Bengal there lies a body of water, often referred to as Lal Dighi (meaning Red Pool). As for commercial trading in Bengal, the East India company came here in 1690 and initially British focused their attention in and around the vicinity of Ft. William- their main settlement.  There were small pockets of areas, and in some of them, Europeans lived in garden houses, but the British resided mainly in the fort and adjacent places. Lall Bagh was one among the small portions around Ft. William and at the center of it there was Lal Dighi or the Great Tank. In the same park in an enclosed Cutchery house there lived a  local Jaigirdar, Laksmikanta Roy Majumdar Choudhury (1570-1649). It is obvious that Lal Dighi and other near-by places had been very much there far before the arrival of Job Charnock, supposedly the founder of Calcutta. Charnock  purchased the Cutchery house along adjacent areas to safeguard company records, etc.
east side of Tank Square Calcutta,1894-puronokolkata
The color of the water in Lal Dighi became a subject of debate  and there are many versions available as to its origin. One has to pick up the most reasonable and acceptable one or two, theories.  Because of the color of the water  turned red during dol - festival  of colors, over a period of time, the name Lal Dighi stuck with the water in the tank.  The other explanation is the reflection of the red color of the old fort used to sparkle in the water of the tank, giving it a sort of reddish appearance, so the tank acquired the name. As you may see, among the many stories, the above-mentioned versions  come much closer to acceptable reasoning..  As years went by, at the initiative of EIC  in 1709,  the weeds and other stuff were removed and the huge pond  was further deepened and lengthened, resulting in the yield of crystal clear water. It ultimately  became a good source of water for the people living near-by.  
1690 Lal Dighi, Kolkata puronokolkata.com
In the 18th century The  Tank Square was in the center of the city, covering  more than  25 acres (100,000 m2) of ground. In 1770s the tank was further dug on order from the government with a view to providing potable water for the public. ‘

It was during Warren Hastings’ time, at his initiative, special efforts were made to cleanse the water and  once it was done, it was embanked and protected.  Lal Dighi in Dihi Kalikata became the most reliable source of water for the people, in particular, the European community. 

https://en.wikipedia.org/wiki/Lal_Dighi

https://puronokolkata.com/2016/02/15/lal-dighi-lal-bagh-calcutta-1690/