The BEST Undertaking may not have lived up to its name, wasting thousands of litres of drinking water to wash its buses, but it’s the Mumbai Metro that is setting the best example in water conservation with a three-pronged approach: Firstly, it has cut the amount of water used to wash the interior of the trains from 200 litres per rake to 20 litres – a whopping 90% cut. Water is also used to wash the exteriors, but 80% of that water is then reused for gardening or other purposes. What’s more, most of the water used for washing is sourced from rainwater harvesting.
To make cleaning easier and reduce water usage, a chemical solution is being used on the floors of the Metro trains to repel dirt. As a result, water consumption has gone down by 90%
Breaking it down
The Metro has a total of 16 rakes, and all of them are washed from inside every day. Officials from Mumbai Metro One Pvt Ltd (MMOPL) said this would earlier consume 200 litres per rake, but in light of the drought, they have now cut this amount down to 20 litres. A special coating was used on the floors to make it easier to clean the trains.
“Due to heavy footfalls in the trains, the floor of the compartments obviously collects a lot of dust and dirt. A durable epoxy coating was used on the train floors to repel dust and dirt, thereby drastically reducing the quantity of water required,” said an MMOPL official.
Officials from MMOPL claim that even though there was no water crisis when Mumbai Metro was launched in June 2014, water-efficient systems were installed to ensure that minimal water is consumed. The decision taken back at the time of conceptualization is paying off now. “From the start of the project itself, MMRDA-MMOPL has been taking measures to save as much water as possible. Every year Mumbaikars have to face water cuts, so we also came up with a solution to use less water,” said an official from the Mumbai Metropolitan Region Development Authority (MMRDA).
The Metro car depot at Four Bungalows in Andheri (W) has an automatic wash plant where the exterior of the trains are washed every other day, using 1,200 litres for each rake. The water required for the external wash is less because of the stainless steel body, which doesn’t collect dust easily. Besides that, mostly harvested rainwater is used to do the washing, after which over 80% of the water is recycled at the on-site waste water treatment plant. The treated water is then used for gardening and beautification of the area.
“Mumbai Metro’s automatic wash utilises about 1,200 litres to wash each train. About 1,000 litres from this is collected and reused. Less than 17% of the water is dispersed due to the gust from the high pressure jets used for cleaning. We used an innovative design idea to make the water recycling efficient. The wash plant was installed on an elevated ramp and the water recycling plant is located underneath it to directly collect the used water,” said an MMOPL official.
Internal wash: 20 litres x 16 rakes = 320 litres
External wash: 1,200 litres x 8 trains = 9,600 litres