Water Management in Chennai
Response from Srinivasan

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Mr. Srinivasan is an eminent Engineer with intense experience in Planning & Design of Major water supply projects .He was responsible for receiving the World Bank Aid for the improvement of Water Supply and Drainage in Chennai. He is well known among technocrats in water related field. He is now the project Engineer for the "New Tiruppur" Project.

Rajan's article has a collection of candid ideas and will be comprehensive if sewed by a connecting thread more cogently.
Basically, water requirements/water availability come under two macro categories.

i. Water of potable quality - for drinking, cooking, bathing etc.
Existing sources : Red Hills (Poondi), Kandaleru (Krishna) and new sources (Veeranam) come under this category.

ii. Water of questionable quality - for other uses Rain Water Harvesting (RWH) comes under this category.

Conveyance of water by rail or lorry does not come under either category. They are emergency services under traumatic care and not to be considered as normal solutions.

There are some certain factual statements, which could be refined.

• Water borne diseases are a better expression than 'endemic'. All endemic diseases are not water borne.
• 'Estimation of water consumption' does not provide for cooking. However, the figures can be reworked and the total figure of 100 litres is acceptable.
• Figures on water availability under RWH need to be rechecked.
  Area of plot : 2400 sq.ft or 240 sq.m.
  Intensity of rainfall : 1.1 m per year
  Total rainfall : 240 x 1.1 or 2.64 lakh litres
  Not all this rainfall can be stored even with best technology and best application of mind as rainfall is scattered. In urban setup with paved roads, the % realisation may only be around 25%.Nett realisation may only be around 60000 litres per annum. Same argument applies for assessment for 180 billion litres for the entire city (area of city =170 sq.km. x 1.1 x 106 x 103/109 ).
• Use of wax or polymer coating for lakes has not been considered suitable for Chennai due to shallowness of lake and consequent high evaporation rates. Technology improvements in proper identification of evaporation retardent coating may help.
• Vadakuthu Treatment Plant is near Veeranam lake (not near Chennai). Slated date for completion is 18 months from commencement (not from today).
• To my knowledge, there is no proposal to sink borewells in 132 slums at a cost of 132 crores. This probably refers to sinking India Mark 2 pumps in slums, which may cost 132 lakhs.
• Conversion of slums as lakes for rain water catchment may not be practical in a metropolitan city where land has a high value. An alternate philosophy could be to rehabilitate temple tanks and swamps like in Basin Bridge / Palliakaranai and divert rain water by lead pipes to these storages .
  
  The whole approach appears to be based on an axiom that rain water harvested could be considered suitable for all domestic uses including drinking. This may be a difficult proposition, as it will require leak proof underground tanks for each house and miniscale treatment easily operable by the occupant with average technical skill .A more practical solution will be -
• For the Government - to concentrate on water of potable quality
• For the citizens - to develop RWH within the house for other uses and help the Government in their efforts.