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Rainwater harvesting & greywater recycling in urban areas_Seetha Gopalakrishnan (IWP)_2014
Rainwater harvesting & greywater recycling in urban areas_Seetha Gopalakrishnan (IWP)_2014
Rainwater harvesting & greywater recycling in urban areas_Seetha Gopalakrishnan (IWP)_2014
Rainwater harvesting & greywater recycling in urban areas_Seetha Gopalakrishnan (IWP)_2014
Rainwater harvesting & greywater recycling in urban areas_Seetha Gopalakrishnan (IWP)_2014
Rainwater harvesting & greywater recycling in urban areas_Seetha Gopalakrishnan (IWP)_2014
Rainwater harvesting & greywater recycling in urban areas_Seetha Gopalakrishnan (IWP)_2014
Rainwater harvesting & greywater recycling in urban areas_Seetha Gopalakrishnan (IWP)_2014
Rainwater harvesting & greywater recycling in urban areas_Seetha Gopalakrishnan (IWP)_2014
Rainwater harvesting & greywater recycling in urban areas_Seetha Gopalakrishnan (IWP)_2014
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Rainwater harvesting & greywater recycling in urban areas_Seetha Gopalakrishnan (IWP)_2014

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This presentation provides a quick look at the basics of domestic rainwater harvesting and grey water recycling.

This presentation provides a quick look at the basics of domestic rainwater harvesting and grey water recycling.

Published in: Environment, Technology
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  • The idea of rain water harvesting can be very powerful for sustainability of groundwater table. Chennai is a decent example. Visit Rain Centre site or CSE site: http://www.rainwaterharvesting.org/
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  • good!!!!!
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  • 1. RAINWATER HARVESTING AND GREYWATER RECYCLING IN URBAN AREAS – THE CHENNAI EXPERIENCE Seetha Gopalakrishnan India Water Portal
  • 2. Rainwater Harvesting - Basics Is this a novel concept?  Not a new technology or an alternative  Adaptations - Traditional vs. Modern designs Why should I harvest rainwater?  No. of rainy days are less – around 60-90 days on an average across India  Cities are usually water starved, not rain starved  Needs - Immediate use vs. Groundwater recharge Is it expensive?  Not very if it is incorporated in the original design How do I go about this?  Harvest rainwater, both from the roof-top as well as around the building – Simple design
  • 3. Rooftop Rainwater Harvesting  Terrace down-take pipes → Underground sump │Overflow from the sump → Dug well  If dug wells are absent, construct recharge wells or percolation pits depending upon space available Consider a building with a flat terrace area of 100 sq.m. Average annual rainfall in Chennai is approximately 1300mm Assume that 60% of the total rainfall is effectively harvested Volume of. water harvested = 1,30,000 x 0.6 = 78,000 litres 213 litres of water/day will be available for the household This is enough to meet the drinking and cooking needs of a household
  • 4. Diversion of rainwater from the terrace into a shallow dug well in an apartment complex
  • 5. Harvesting the Driveway Runoff  Rainwater that falls around the building is usually wasted  Not good for potable uses, but definitely worth using for recharge  Gutter near the gate does the trick  Water collected at the gate → Recharge well
  • 6. Greywater Recycling •Almost 60% of the refuse water from our daily usage is good, quality sterile water - Can be easily cleaned up •Plants remove all the organic material •Water is further polished by soil bacteria as it travels down the soil •The cleaned water can be safely used for flushing and gardening •Excess can be put into the soil to augment the shallow water table Daily Water Usage Flushing - 35% Kitchen - 15% Bathing and Washing of Clothes - 50%
  • 7. Characteristics of a good groundwater recharge system Both from Rainwater harvesting and Greywater recycling  Completeness -Both rooftop and driveway runoff water to be harvested.  Apportioning of water–To avoid overload of any one system, leading to overflow and loss.  Proper design - Volume of water likely to flow through and the nature of the soil in the area should be considered.  Maintainability - Design should incorporate features allowing for periodic maintenance of the structure.
  • 8. Annual rainfall averaged over the last 50 years falling over the 174 Sq km area of Chennai is 127cm. If this is harvested, every citizen can get 135 litres per day Chennai is rain-rich but water- starved  No perennial river nearby  Rain from SW and NE monsoons  Macro-supply - Reservoirs are woefully inadequate What should be done?  Reduce dependence on Metro water Supply  Increase dependence on sources within one’s premises  Conjunctive use of aquifers – shallow & deep The Chennai Experience
  • 9. Government Initiatives Tamilnadu is the first state in India to make rainwater harvesting mandatory 1) Tamil Nadu Municipal Laws (Second Amendment) Ordinance, 2003   Inserted Sec. 255A in the Chennai City Municipal Corporation Act, 1919 which made Rain Water Harvesting mandatory Similar changes were made in Municipal laws of other major cities as well 2) Rain Water Harvesting Structures in Buildings Amendments to Building Rules 3) Ground Water Potential Villages including Well field & Suburban Area 4) Act to amend the Madras Metropolitan Area Groundwater (Regulation) Act 1987 Rain Centre Chennai RWH Survey - 2006 •After the record rainfall of 250 cm. in 2005, there was a phenomenal rise in groundwater table •Survey revealed that the Groundwater table had risen by minimum of 6 m. and a maximum of 8 m. in the entire city •Shallow aquifer recharge very successful -Temple tanks which were previously empty had water in them

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