Looking ahead: Water and sanitation

The city government has set out its vision for the future as far as water and sanitation are concerned. It wants to have 100 percent piped water supply coverage in the municipal corporation and surrounding areas by 2016. The aim is also to have a per capita water supply of 150 LPCD by increasing the hours of supply to eight a day by 2011, and 16 a day by 2016. By 2021, the city looks forward to having a 24-hour supply.

It also says that it plans to reduce distribution losses to 20 percent by 2016 and do a 100 percent recovery of its costs. However, it is a tall order when compared to its present situation.

How will Chennai cope with its source constraints? Chennai’s water supply is highly dependent on the returning monsoons. The city remains at the tail end of all sources.

Currently, in the best of situations, with huge investments to bring even seawater to its people, the city manages a supply of barely 90 LPCD. The slightest change in any of its sources can lead to a drop in supply of as little as 35 LPCD.

The city has estimated that by 2016, it will need about 1,800 MLD of water – its current supply is close to 800 MLD. By 2010, while water availability had jumped to 1,200 MLD, demand had also increased.

The options to augment its water sources are limited, says the city government. It wants, therefore, to concentrate on the sea for its future. It is banking on building desalination plants up to a capacity of 700 MLD, for which it is busy securing land and loans.

Chennai MetroWater has had the advantage of being a public utility which has kept a reasonably good control over its finances. But its increasing dependence on more expensive water projects will jeopardise this position. Its cost of water is increasing and this should be a source of worry for its planners – particularly as it charges high rates from consumers and still needs huge investments in managing sewage.

As said before, Chennai has the country’s most successful rainwater harvesting programme. In 2001, the city introduced municipal by-laws which make rainwater harvesting structures mandatory in all multi-storey buildings. Then, in August 2003, faced with an unprecedented drought, the state government passed an ordinance making rainwater harvesting mandatory for all buildings (existing and new) in the city. It set a deadline of October 31, 2003, for the process to be completed and put its most competent officers in charge of ensuring that this was done.

The ordinance mandating rainwater harvesting came into effect just as the city was in the grip of its worst ever water crisis. People were receptive to the idea since they understood the value of water. They wanted to save and recharge their home dugwells. The combined result was a successful programme.

A household level sample survey, done in the winter of 2003-04 covering some 1,500 households in the city, established the importance of rainwater harvesting. The vigorous and intensive publicity campaign undertaken by the state administration had worked. People understood the concept of rainwater harvesting and wanted it done in their homes. The problem was that there were too few professionals with knowledge and experience to cope with the scale and speed of the programme. Still, the impact was high.

As much as 92 percent of the respondents of the survey reported that they had installed rainwater harvesting structures – 80 percent of these were structures to channelise rooftop water into tanks and recharge structures around dugwells.

The question that arose was how Chennai could now expand such a system to make a difference in the city’s water future. A model, developed by researchers from Stanford University in the US, has looked at this issue. Without even harvesting, at least 9 percent of rainwater in Chennai makes it to the aquifer. The model estimates that using policy as a driver, rainwater harvesting may be implemented to increase recharge to 27 percent of the rainfall. The results show that aggressive rainwater harvesting keeps the aquifer recharged, as a result of which lesser numbers of private wells run dry during droughts and the tanker market gets reduced by almost one-third. The study recommends that investments improve the efficiency of water use, combined with aggressive strategies for recharge of groundwater, provide the best options for the future.

But if rainwater harvesting has to be a key option for its water supply, then it must go beyond catching rain from rooftops, and move towards protecting its vast lakes and ponds. Currently, these are under threat from builders and polluters alike. The developers have not even spared the Chembarambakkam Lake, which is the key for the city’s water supply. In 2007, the state government announced plans to build an industrial park near this lake. A group coming together as the Association of Chembarambakkam Lake Drinking Water Consumers filed a petition in the Madras High Court. The court ordered stoppage of work. Finally in 2008, the government ordered that the lands around the lake would remain agricultural.

This protection needs to be given to all tanks and water bodies in and around the city, argues water expert A Vaidyanathan – “The tanks and wetlands in the city play an extremely important role as a source of irrigation and domestic water and recharge structures.” His study notes that the number of tanks is more than 1,500 and their rated storage capacity is around 939 million cubic metre (MCM). But these structures are in a serious state of disrepair. What is needed is to commission a detailed survey of the wetlands using remote sensing, and to use this study to prioritise regeneration and provide legal protection to each water structure.

Chennai had some past experience in using seawater for drinking – MetroWater built a battery of reverse osmosis plants in the colonies along the sea – mostly inhabited by fisherfolk. The aim was to provide drinking quality water from a source close to where people live. These plants – three of a capacity of 0.15 MLD and two of 0.1 MLD – are small, built specifically for drinking water.

With this experience, the city had tasted salt. In 2005, the Tamil Nadu government signed an agreement with a private party to build and operate a 100-MLD desalination plant for city water supply. The Minjur plant went operational in 2010. It takes seawater and then puts it through a series of water treatment and reverse osmosis technologies to remove salt.

According to senior municipal officials, the capital cost of this plant was Rs 473 crore. Under the agreement, MetroWater will pay the private company Rs 48.66/kl for the next 25 years. This rate does not include power, which is paid for separately, because of its variable costs. If this is added to the bill, then it would cost MetroWater a further Rs 10-12/kl, taking water costs to Rs 59-61/kl for this seawater. But officials say the price is worth it as it gives them a reliable source.

So, the expense is not a deterrent for the city. It is now investing in another 100-MLD plant at Nemmeli, this time owned by the water board itself. The cost of this desalination unit is being supported through the Union government’s JNNURM funds. The cost of the project has been divided – part one comprises construction and operations and maintenance for seven years, awarded at a cost of Rs 1,033.68 crore (roughly half and half). The plant is expected to be ready by December 2011.

But it does not stop here. The city is also making provision for two more plants. Clearly, the planners think that the sea and not the rain is the answer for the future. What this expensive water will do to the city’s water accounts is not yet clear.

The reuse of sewage and wastewater for industrial and even domestic water use is another option worth exploring. Chennai has the distinction of having the country’s first recycling project – the city’s sewage was sold to the Chennai Petroleum Company Limited (CPCL), which in turn used reverse osmosis technology to filter the sewage and turn it into usable water. This industry found sewage more reliable than water and the costs were low as compared to its use.

The CPCL tertiary treatment plant, with a capacity of 41 MLD, does ‘reclaim’ sewage from the city. Better still, MetroWater earns Rs 12 crore per annum from the sale of sewage to this industry. This approach to turn waste into wealth needs to be promoted in this city of water stress and scarcity.

Chennai has shown that it can work on improving its water management system. Now it must work to provide new and innovative ideas to provide it water, in the worst of drought, and for all.