Today in New Delhi, India
Jun 14, 2019-Friday
-°C
New Delhi
  • Humidity
    -
  • Wind
    -

HT spotlight: Poor response to rainwater harvesting in Pune

Dams at an all-time low. Groundwater depleted. This monsoon it is time to reap a harvest of water. Here’s how and why

pune Updated: Jun 14, 2019 15:50 IST
Prachi Bari
Prachi Bari
Hindustan Times, Pune
Pune,Poor response,rainwater harvesting
Kumar Sahwas society, Baner-Pashan link road, is in the process of installing a second rainwater harvesting unit ahead of the monsoon this year.(Milind Saurkar/HT Photo)

Rainwater harvesting is mandatory for larger societies in Pune since 2007, yet, statistics from Pune Municipal Corporation’s (PMC) property tax department reveal that the number of properties applying for, and receiving a property tax rebate, have increased by just 194 in 2018-19.

The tax rebate is given to properties with an operable rainwater harvesting system in place - a five per cent rebate in property tax and an additional 5 per cent if societies also have solar energy and vermicompost.

Statistics show that 1,778 properties received a tax rebate for the year 2018- 2019, as compared to 1,584 properties.

Enquiries about rainwater harvesting are many, but actual work is still to catch on in the city.

Col Sashikant Dalvi (retd), national coordinator, water conservation, Climate Reality Project, India; and director, Parjanya: Rainwater Harvesting Consultancy, says, “Various national and international weather agencies are predicting a delayed and deficit monsoon. The four dams Temghar (under repair for the last two years); Varasgaon at 34 % capacity; Panshet at 43 %; and Khadakwasala at 53 %; it will not be a year of sufficient water supply to a city with a population of 40 lakh. Hence, as a water conservation expert, I have been talking about the need for water availability with possible solution of looking at availability of water in all possible reservoirs including rainwater potential.”

Dalvi states desilting of dam reservoirs has resulted in a 30 per cent reduction in water storage capacity, this is besides other reasons like unequal water distribution, leakage in water supply pipes, depleting ground water table, non-implementation of ground water recharge policies and depleting forest cover.

Making the most of rainwater is a necessity
City has an average annual rainfall of 750mm, and one acre of catchment area receives 30 lakh litres of rainwater annually. Forecast for monsoon is that a delay is likely, but here’s what you need to know about rainwater harvesting
Identification of catchment area to collect water. Can be terrace areas, car parking, roads or even concrete surfaces.
Installation of filters
Installation of dummy bore-well or recharge shaft, for filtration (water percolates from here to the main bore-well)
Determination of the Collection point or the Storage unit ( bore-wells or water tanks)
Identification and installation of a water retrieval system to draw water from the storage units (Pumps)
Maintenance: Cleaning of catchment area, installation of filters, etc.
PRIMARY SOURCE
Rainwater is one of the primary sources of water. The idea of rainwater harvesting is to make optimum usage of the freely-available water. This helps in recharging and maintaining groundwater level and thus minimises the load on the treated water supply.
DOS AND DON’TS
Harvested rainwater is either for direct usage or for recharging aquifers. It is important to ensure that the rainwater collected is free from pollutants. Following precautionary measures should be taken while harvesting rainwater
Roof or terraces used for harvesting should be clean, free from dust, algal plants etc.
Roof should not be painted since most paints contain toxic substances and may peel off.
Do not store chemicals, rusting iron, manure or detergent on the roof.
Nesting of birds on the roof should be prevented.
Terraces should not be used for toilets either by human beings or by pets.
Provide gratings at mouth of each drainpipe on terraces to trap leaves debris and floating materials.
Provision of first rain separator should be made.
Do not use polluted water to recharge ground water. Ground water should only be recharged by filtered rainwater.
Before recharging, suitable arrangements of filtering should be provided.
Filter media should be cleaned before every monsoon season.
During rainy season, the whole system (roof catchment, pipes, screens, first flush, filters, tanks) should be checked before and after each rain and preferably cleaned after every dry period exceeding a month.
At the end of the dry season and just before the first shower of rain is anticipated, the storage tank should be scrubbed and flushed off all sediments and debris.
Source - http://www.mppcb.nic.in/rwh.html

“In most of the rapidly growing cities, civic authorities are unable to cater to daily water needs of citizens, resulting in less than authorised daily water supply of 135 litres of water per person. In Pune, it varies from 350 litres to 80 litres of water per person,” says Dalvi, explaining the basic water intake and the need for rainwater harvesting.

“My society, Lunkad Green Land 2 in Viman Nagar Pune has nine lakh litres of annual rain water potential. With the implementation of rainwater harvesting in June 2002- 2003, it has raised ground water table of our borewell. Yield of water increased to nine hours a day. Thus rain water potential anywhere in the world is a primary source of water availability,” says Dalvi.

A defunct rainwater harvesting system at Yashwin society, Mhalunge. Many housing societies are equipped with systems which are defunct. ( Milind Saurkar/HT Photo )

First Published: Jun 14, 2019 14:46 IST