PUNE: The writing is on the wall. The city’s population is rising and its water needs are growing by the day. So the city must save water through as many ways as possible or faces cuts year after year.
Among the options, rain water harvesting (RWH) stands out as the most workable solution. It has been tried and tested in several metros like Chennai and Bangalore where it has improved groundwater levels significantly and made new buildings in Mumbai explore the option.
While individual efforts in the city to store rain water to recharge ground water levels stand out as classic examples and many citizens back the idea and want the Pune Municipal Corporation (PMC) to make it mandatory for all buildings, the civic body says it is not such a feasible way to save water. Experts find it a question of willingness.
At the top, the state government is keen on rain water harvesting. The water supply and sanitation department had issued a government resolution in 2002 approving RWH as a means of improving water supplies. The GR details various RWH techniques, their costing and availability of funds.
However, civic officials want the push to come from the state government. “The PMC is waiting for the state government’s directives to make a RWH compulsory for new constructions in the city. As of now, it is voluntary for new constructions. Once the state issues directives, the civic body will follow it,” said PMC’s deputy city engineer Rajendra Raut.
Unlike Chennai where the government made it mandatory for all buildings including government offices to have RWH in 2003, the PMC has said the costs and infrastructure made it an unfeasible option here.
Of the 6.5 lakh properties in Pune, only some 600 have implemented RWH. The Pune Municipal Corporation (PMC) grants concessions in property tax to societies that implement one or two of the eco friendly techniques like rainwater harvesting, solar heating techniques or vermi-composting.
A five per cent rebate is granted if any one of the techniques is followed and ten per cent if two techniques are implemented. City engineer Prashant Waghmare said, “We have not made it compulsory. It is not possible to ask old property owners in the city to opt for this technique as they do not have the space or the side margins required to set up the system.
“It is not feasible to make rainwater harvesting compulsory. It involves cost and infrastructure. At many places the geological conditions do not permit such a system, especially where the hard rock forms the base of the land. Setting up such an infrastructure is expensive in such cases,” said Raut.
RWH consultant Jyoti Panse said the techniques was not prohibitive. “Compared to the price we pay for water during crises, the RWH investment is less and a one-time investment.
Until the PMC opts for a metered water system, people will not understand the value of water. Once water is tagged with value, people will understand its worth and the importance of rain water harvesting,” she said.
That there is little initiative from the citizens too is apparent. A total of 8,063 properties were given tax concession in 2009-10. According to the property tax department, 1,185 had implemented solar heating and 2,171 had taken up vermicomposting.
In sharp contrast, just one property had rain water harvesting. In a combination of two techniques, 4,227 properties had both solar and vermicomposting while 579 had rainwater harvesting and vermicomposting. Willingness will be the bottomline for RWH to gain ground, said Panse.
All That You Want To Know About Rain Water Harvesting
Can I harvest rain in my own house?
Yes. Structures to harvest rain require little space. A dried borewell, a row of soak pits or a tank concealed below the ground are all that you need. The open spaces like rooftops and the ground can be used as your catchment (surface to catch rain).
How much will it cost?
Costs vary depending on the area of your roof and other structures that you will use to harvest rain. But it does not require major construction work, so the expenses suit most pockets. Find out for yourself on websites including http://www.rainwaterharvesting.org
Who will build it and how long will it take?
You need someone who understands RWH. It is simple, but it still needs someone who has experience in the principles of rainwater harvesting. Then a skilled mason or a plumber can do the job for you within 10 days.
Who will it benefit?
Your groundwater will get recharged. But as groundwater finds its own way, your neighbourhood will gain too. So for best results, get all your neighbourhood societies to become rainwater harvesters as well.
What will be the quality of water?
You are putting rain water into the ground, which once contaminated, cannot be cleaned easily. Do not let water with sewage or other dirt flow into your recharge pits. This is why the cleanest rainwater is from our rooftops. There are also filters to keep some dirt out.
Does it require maintenance?
Once or twice a year, at very little cost. Remember rainwater harvesting means that you have to get involved. This is about making water all our business and about building our relationship with water, with the environment. Harvest rain and learn the value of each raindrop.
What are types in rainwater harvesting?
Rooftop RWH is the one in which roof-water is collected and directed into a bore well pipe after filtration or can be stored in a storage tank and used for non-potable requirements
Collection of rainwater that falls on the ground is called surface rain water harvesting. This water is polluted as it comes in contact with the ground, so it should be recharged into the ground by means of filtering recharge pits
(Source: Centre for Science and Environment, New Delhi)
Why Rainwater Harvesting
- It is a simple, economical and ecofriendly technique of preserving every drop of water falling on the earth.
- It is the process of gathering and storing rain drops and preventing runoff, evaporation and seepage for its efficient utilisation and conservation.
- It is an effective option to gather rain water and store it.
- Harvesting helps utilise a large quantity of good quality water which otherwise goes waste.
Just A Little Space
Harvesting rain needs little space. A dried bore well, a row of soak pits or a tank concealed below the ground are all that is needed. The open spaces, rooftops and ground can be used as catchment area. Groundwater will be recharged, and as groundwater finds its way around, the neighbourhood will gain too.
The cost is calculated based on the size of the building and various other considerations. Pune receives a total rainfall of around 700 mm through the year. An apartment block or a bungalow with 1,000 sq ft terrace can save around 60-70,000 litres of water every year.
Hardware costs for installing a rainwater harvesting system is between Rs 10 and Rs 12 per sq ft of terrace area. Harvested rain water can be diverted to existing bore well water or flushing water storage tank.
Approximate cost of this storage tank is Rs five to six per litre of the tank capacity. A building of Rs 24 flats will incur an expense of about Rs 1 lakh for installation of the system.
This article was reprinted from the Times of India.