City Water Walks Mumbai

The first edition of the Mumbai walks saw us visiting Powai lake as permissions for our visit planned for Vihar lake didn’t come through. Conducted with the support of Sanctuary Asia and led by Dr. Parvish Pandya, we learnt a great deal about the situation in Mumbai.

The History

Mumbai is a city that was found in 1507. The city consists of 7 islands, which however now seem to look like one big chunk of land. The Portuguese and the Britishers anticipated that Mumbai would be a bustling place, given the proximity to the sea. They anticipated the needs of the city and constructed lakes in the forest, now known as Sanjay Gandhi National Park. The lakes Tulsi, Vihar and Powai were surrounded by forests. This combination of man made lakes and forests is still responsible for supplying water to the city. If you are unsure of how this works, let me explain it using an example shared by Gaurav. Imagine a bald man and a man with curly hair. Now imagine pouring a jug of water on both these heads. As you can imagine, all the water just drains off the bald man’s head. Whereas with the curly hair person, the water is drained slowly. Now the hair on the head is the forest on the land. Wherever there is forest, it will soak in all the rainwater falling around and it will let this water out slowly. This is how forests help in conserving water. The water which falls on deforested land, actually causes erosion. Mumbai is a unique city in a way that there are many forests / mangroves within an hour’s drive from the city, courtesy Western Ghats.

Islands of Bombay and Colaba. Source: British Library
Islands of Bombay and Colaba. Source: British Library

Ground Water

The groundwater situation in Mumbai is not great says Prof Parvish Pandya, our water expert for the first walk. Metropolitan Mumbai never felt the need to use groundwater because of abundant water via the lakes and existing infrastructure to supply water. Traditionally, housing societies in Mumbai didn’t have wells in their compounds and the trend to build wells and pump groundwater started off very recently. This water is very unsafe and contains a lot of pollutants, to the extent that it could prove dangerous for direct human contact but can be used for flushing toilets and most societies use the same water for the purpose of gardening too. Plants have the capability to break down the bacteria from the polluted ground water, an ability that humans do not possess. The groundwater levels are pretty high in Mumbai as of now because they have rarely been used, but over time these aquifers have been polluted.

Facts: Groundwater usage in Mumbai is unregulated. 57.6% of Ulhasnagar depends on groundwater. Vasai Virar areas use 10 million litres of well water per day, which is a very significant amount. A comprehensive database on wells, aquifers and groundwater table is not in place.[2]

Pre & post monsoon ground water situation in Mumbai. Source: CGWB report.
Pre & post monsoon ground water situation in Mumbai. Source: CGWB report.

Lakes and STPs

Given that Mumbai was always a hub for business activities, the city had time to build it’s infrastructure and expand at a much slower pace when compared to cities like Bangalore or Gurgaon which sprang up almost overnight due to the boom in the IT industry. Mumbai has this particular advantage over these other cities, however it is now under stress, with the development plans to chop down the forests at Aarey. The government is trying to promote rainwater harvesting as a localised solution to conserve water, given the growing demand in the city. However these plans work best when the society is being redeveloped and the residents are really concerned about reusing water. Another way to tackle this problem is to have decentralised STPs, where water from surrounding buildings is treated locally, a part of it is reused by the buildings themselves and the remaining slurry is sent ahead to the main STP.

Powai Lake. Copyright: Stamen Maps
Powai Lake. Copyright: Stamen Maps

The condition of the Mumbai lakes is nowhere close to Bangalore lakes which caught fire, but it seems it is difficult to get attention of everyone unless lakes start frothing and catch fire! In Mumbai, the population explosion was slow as compared to Bangalore. So the citizens in Mumbai had enough time to realise that the natural resources are being depleted, form action groups and get their voices heard. Whereas for Bangalore, the population explosion was so quick that locals never got enough time to make their voices heard, or even realise what is happening to their city.

Facts: Thane has 35+ lakes, Navi Mumbai has 25+, Kalyan Dombivali has 29. Mira Bhayendar has 3, and Vasai-Virar has 4-5 lakes. None of the above use lake water for their purposes. Only Bhiwandi uses lake water, but ironically, the water treatment plant doesn’t function, so untreated water is supplied.[2]


There was a time when Mumbai had rivers and forests around them, however, today most of the so called rivers have become mere sewage drains. The industries dump their industrial waste, there isn’t any proper sanitation and there are shanties all around. Take the case of the Mithi River, right at the source as soon as the river exits the Vihar Lake complex, the water turns dirty and starts smelling. Similarly, the rivers in Thane – Bhiwandi area are so bad that there are places where the water doesn’t really exist but it is just a black-greyish viscous jelly like substance. 

Condition of the Mithi 1. Copyright: Priyans Murarka
Condition of the Mithi. Image: Priyans Murarka

There are 6 rivers in Mumbai, namely, Mithi, Oshiwara, Poisar, Tansa, Tasso and Dahisar. Mithi originates from Vihar lake with a secondary source at Powai Lake and empties into the Arabian sea at Mahim Creek. Oshiwara river begins in Aarey Milk colony and empties into the Arabian sea via Malad Creek. Poisar starts in SGNP and empties into the Marve Creek into the Arabian sea. Funnily, Ganesh Visarjan no longer happens in this river because it is too dirty. Tansa and Tasso are other small rivers in the city. Dahisar river originates at Tulsi Lake, SGNP and drains out in the Arabian sea at the Manori Creek.

Fun fact – the area was so picturesque that Bollywood films were once shot here, Dilip Kumar and Vyjayanthimala shot Naya Daur on the banks of the river.

Condition of the Mithi 2. Copyright: Priyans Murarka
Mithi as it flows through the city. Image: Priyans Murarka

Indulging in such an interaction makes us re-think what we’re doing to nature, one of the intentions with which these walks have been designed. People ask, how does one sensitize factory owners and workers towards the damage they are doing? How do we get the common man to care and not pollute? How do we get our civic authorities to perform their duties?  One idea is to expose them to the nature and beauty around them, another is to make them understand that their actions are crimes against their own children or maybe if we started holding people accountable for their actions that could work. But unless a majority of the people start focussing on these issues, we’re not going to be moving ahead.

Early in the morning before the participants had arrived, I observed two men voluntarily cleaning the lake. They were collecting the floral immersions from Ganesh Visarjan which surfaced on the lake, said they had been doing that for a week. They used a stone tied to a string, threw it into the water, dragging the leaves and the flowers to the edge of the lake as they pulled at it. Someone later asked, “On a scale of 1 to 10, where 10 is the absolute point of no return, how bad is the water situation in Mumbai?” Prof Parvish said, “If it weren’t below 5, I wouldn’t be staying here in the city”. 

Overall, Mumbai is still in a better state resources wise. Mumbaikars are pretty lucky to have huge mangroves accessible in roughly an hour’s drive from the city. There are still spots left in the city where one can observe migratory birds, telling us that the forests are still there. The city has a national park in the suburbs, which roughly occupies almost 1/4th of suburban Mumbai. To draw a comparison, Central Park occupies 0.06% of Manhattan (not NYC). Mumbai can tap into the existing Western Ghats for more resources, but unless they are properly managed, what’s the point? We should also not ignore the cost the future generations would be paying for us using up these resources. Critical thinking, mass awareness, stringent policy enforcement should be at the front and centre so that we don’t continue making the same mistakes. These walks are meant to educate, sensitize children, adults, corporates, all alike and we hope to see you joining us on the next walk.

Mumbai Land Cover. Source: IIPS Mumbai
Mumbai Land Cover. Source: IIPS Mumbai

The City Water Walks initiative aims to introduce the urban dweller to the basics of the local water infrastructure, affording an insight into where does water come from, what happens to it and where does it finally end up. Write to us at if you’re interested in doing a Water Walk in your city. Read about our walks in other cities here: Ahmedabad Water WalksChennai Water Walks.

More reading and references:

1: Bombay map credit: British Library

2: SANDRP Report: Dams in tribal belt of Western Ghats for the Mumbai Metropolitan Region, March 2014. -

3: India Water Portal study: Why Mumbai must reclaim its Mithi -

4: Powai Map: Map tiles by Stamen Design, under CC BY 3.0. Data by OpenStreetMap, under CC BY SA.

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