Desalination plants will bridge Chennai’s water demand-supply gap: CMWSSB MD

With Veeranam Lake drying up and Cholavaram Lake with little water, how is Chennai planning to meet summer demand? We asked CMWSSB.

With the onset of summer, Chennai has already started facing water woes. Veeranam Lake, one of the sources of drinking water supply for Chennai has dried up. Meanwhile, the storage level in Cholavaram Lake has come down to 9.99%. As of May 5, the reservoir sources in the city have a storage of 49.42%. Will Chennai face yet another drought like in 2019? This is one fear that residents of the city come face to face with every summer. And this year seems to be no different.

To know how the Chennai Metropolitan Water Supply and Sewerage Board (CMWSSB) is planning to manage the water supply for the Chennai residents for this summer, we spoke to the Managing Director of CMWSSB, Dr TG Vinay.

Dr TG Vinay, CMWSSB Managing Director, talks with Citizen Matters about the plans to manage the water supply demands in Chennai for this summer.
Dr TG Vinay, CMWSSB Managing Director, talks with Citizen Matters about the plans to manage the water supply demands in Chennai for this summer.

Excerpts from the interview:

Chennai and its water demands in summer

There has been a historical demand-to-supply gap in the water supply system in Chennai. Why do you think there is such a gap?

Normally, we supply 110 litres per capita per day to the residents of Chennai. However, the standard for a metropolitan city is 135  litres per capita per day. The population of Chennai is around  80 lakhs. If we take that into account, we are supposed to supply 1,080 MLD. Currently, we are supplying around 1,040 to 1,070 MLD. If not for the Veeranam Lake drying up, we would have crossed 1,100 MLD of water supply. Now, the supply is a little less owing to the deficit from the Veeranam source. 

Read more: Waiting for water: Thoraipakkam residents demand speedy implementation of CMWSSB scheme

Ensuring regular supply

How is the CMWSSB planning to meet the water supply demands in Chennai this summer?

Our primary sources of water are the surface water reservoirs and the desalination plants. We have three desalination plants — one in Minjur (100 MLD) and two in Nemmeli (110 MLD and 150 MLD). On average, we are supposed to get 300 MLD from the three desalination plants. The 110MLD desalination plant in Nemmeli is under maintenance to replace the RO membranes in the plant. While it is supposed to supply 100 MLD, we get only around 70 to 80 MLD.

The recently inaugurated plant in Nemmeli with 150 MLD capacity will take time to stabilise. We now supply around 130 MLD to 135 MLD from this plant and in a phased manner we will increase the supply. Minjur is also under long-term maintenance. Except for Veeranam, all other sources are stable now.

We draw 42 mcft from all the lake sources per day to supply the city. This takes into account the loss of water due to evaporation. The total storage from all the reservoir sources as of now is 6,500 mcft excluding dead storage. This would suffice for 150 days. We are in a position to comfortably supply water till the first week of September.

Apart from that, we have 26 large borewells in North Chennai’s Thamaraipakkam area. We can draw 15 MLD from there. We are testing the motors and getting it ready now. If necessary, we will use this by end of May.

This apart, we have two main quarry sources – Sikkarayapuram and Erumaiyur. We can draw 25 MLD together from both of these. This will also act as a buffer source.

Challenges with water sources drying up

The Veeranam Lake has already dried up. Last year by the same time, the Veeranam Lake had 589.00 mcft. What alternate arrangements for water supply have been made to meet the needs of localities served by this lake?

We draw around 165 MLD of water from the Veeranam reservoir. This not only includes the water from Veeranam Lake but also other smaller sources like NLC mines and borewells. Currently, the supply from Veeranam Lake is nil. Currently, we are getting around 65–70 MLD from the NLC mines and the borewells together.

In the first week of March, Chief Minister inaugurated the 150 MLD-desalination plant by interlinking the pipelines from the Veeranam and Chembarambakkam sources with the pipeline from the desalination plant in Nemmeli. The deficit of 90 MLD is met by this plant. Therefore, we are ensuring uninterrupted supply to areas in South and Central Chennai.

Read more: Looking back for answers: Can Chennai reclaim its relationship with the water commons?

On issues with desalination plants in Chennai

Residents who get water from the Nemmeli desalination plants have complaints about the quality of the water supplied. They say that the TDS is way more than what is prescribed. How is the CMWSSB planning to address this issue?

The old desalination plant in Nemmeli is under long-term maintenance now. We are replacing the RO membranes and once that is done, TDS levels will come down. We have interlinked the old and new desalination plants in Nemmeli. We are taking 10 MLD from the new plant and blending it with the supply from the old plant. This will also reduce the TDS.

Experts and environmentalists have raised concerns over the environmental impacts of desalination plants. Has the government taken into account such inputs? What has been done to address these concerns?

The new desalination plant in Nemmeli has an advanced mechanism to address the issue of brine being let into the sea. Earlier, the brine was released at one particular place in the sea. Now, the brine is let in through micro outlets in the diffuser across a 1 km stretch which will ensure that the marine environment is not affected. We are regularly monitoring the marine environment through the National Institute of Ocean Technology (NIOT) in Chennai.

Are there any plans to give piped water connections to areas which have been waiting for water supply for a long time like OMR etc? 

The Neelankarai water supply scheme was delayed due to a land dispute. Except for this, several water supply schemes for the added areas in both ECR and OMR  have been commissioned and put to use. In a few months, all the newly commissioned schemes will be provided with service connections. By the year-end, we will supply water through pipelines to all the added areas in ECR and OMR.

Read more: Many reasons for Chennai residents to rely on private water tankers

On permanent solution to meet Chennai’s water demands

Areas that do not have piped water connections heavily depend on water tankers which charge an exorbitant amount during summer. What measures are you planning to take towards regulating the water tanker prices and ensuring the private tankers do not exploit the groundwater resources?

We have an MoU with the private water tankers in Chennai. We have a ‘dial for water’ system, where people can call and book a lorry water supply with CMWSSB and get the water within 24 hours. We have reorganised our tanker lorries so that we have the lorries exclusively for apartments and residential areas. We have increased the number of tanker lorries and have added more trips since January. While there were 23,000 trips in January, we have increased it to 29,000 in March.

We did have a good amount of rainfall during the northeast monsoon, yet a few areas in Chennai are already starting to face groundwater depletion. Is the CMWSSB looking at raising awareness about groundwater recharge and rainwater harvesting practices among citizens?

We conduct a campaign during the northeast and southwest monsoons to create more awareness among the public on conserving rainwater. We tie up with the NGOs and other stakeholders to intensify the campaign.

Long-term answers to water supply woes

Taking water from quarries was done even in 2019 when Chennai faced a historical water crisis. We have similar plans even now. What do you see as permanent solutions to the issue?

As part of the decentralised water distribution policy, tertiary treatment ultrafiltration plants (TTUF) and water treatment plants (WTP) have been established around the lakes in Chennai. For instance, the treated water from the TTUF in Nesapakkam is let into the Porur Lake. This recharges the Porur lake. The water from the lake is taken to the WTP for redistribution to the city. We are now working towards enhancing our capacity to use treated water.

Porur WTP is being operated now. Kolathur WTP is commissioned. Construction works for small-capacity WTPs are underway in Perungudi and Perumbakkam. This will help to recycle the treated water, recharge the lakes and take it to the distribution network.

Construction works are also underway for the second pipeline from Chembarambakkam. Today we are drawing around 260 MLD from Chembarambakkam. Once the second pipeline is commissioned, we will be able to draw an additional 200 MLD of water and supply it to the city residents.

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