The Hindu 19.12.2011
Rooftop turns harvester for drinking water
INNOVATIVE: N. Arunachalam, former Chief Engineer, PWD, explaining the
functioning of rooftop rainwater harvesting system at his house in
Kadachanendal in Madurai. — Photos: R. Ashok
No day passes in the city without a leakage in the
drinking water pipeline being reported. Similarly, complaints of sewage
water mixing with drinking water are not uncommon here. Piped water
supply takes different other manifestations too, like “erratic, low
pressure, unequal distribution and supply at odd hours” that makes daily
life difficult for many of the residents.
It is
common to hear people rue that though the Corporation purifies water to
the quality of ‘mineral’ water, what the people actually get through
their taps on many days is unpotable or of poor quality.
For
those who try their luck to quench their thirst with the ground water,
the quality of water in many places is quite alarming.
Going
by Prof. T. Vel Rajan, of Civil Engineering Department of Thiagarajar
College of Engineering, the ground water quality index (WQI), has turned
worse than what he categorises as “very poor.” While the WQI between 76
and 100 has been categorised as “very poor,” the quality of groundwater
in many pockets was in the range of 120 to 220.
Stating
that the geological formation in Madurai per se was not in favour of
giving quality ground water, Mr. Vel Rajan says allowing liquid part of
the sewage (in areas where underground drainage system does not exist)
to enter into the sub-soil system through septic tanks further pollutes
the groundwater.
“Even though our drinking water
comes from river, we need to be mindful of the activities we do, that
may pollute the ground water,” he says.
Former Chief
Engineer of Madurai Corporation, K. Sakthivel, raises an alarm saying
the brick-made manholes in underground drainage system allows seepage of
sewage into ground water. This was noticed in Duraisamy Nagar and
Karpaga Nagar and the only way to arrest it was to use concrete for
constructing manholes, he says.
Former TWAD Board
Superintending Engineer, S. Kaliyamoorthi, suggests that such problems
can be avoided if the authorities go by material consideration and not
cost consideration while formulating drinking water or underground
drainage schemes. “Using pipelines made of right material will solve
such problem, though it may cost higher,” he avers.
Dr. Velrajan’s study also found that benzene was found in ground water in select areas.
The
increased benzene content in ground water was not due to petroleum
leakages but due to other sources like vehicular emission, industrial
effluents and fertilizers.
Artificial recharge was
the best way to improve ground water quality, he feels. However, the
city residents and those living in adjacent areas need not panic over
the alarming status of ground water.
Former Chief
Engineer of Public works Department, N. Arunachalam, has a simple way to
overcome the pressing problem. “Roof top rain harvest” is what he
advocates to the residents to keep their water worries at arm’s length.
“My
family members have never used water supplied through pipes or ground
water for the past 26 years,” he says with a sense of pride.
An
expert, who has worked on rain water harvesting, has set up roof top
harvesting at the PWD Circle office here where, he says, the system has
been functioning well for several years, improving not only the ground
water table by seven metres, but also its quality.
He
suggests construction of filter tanks (using pebbles and fine sand
mixed with charcoal powder) just below the roof and placing the
collection tank just below it, so that the rain water could be harvested
in the kitchen using gravity.
“Such a system gives
us not only good health, but also helps in saving electricity,” he said.
Mr. Arunachalam uses boiled water that is filtered using ordinary
candle filters for both cooking and drinking purpose.
While
Madurai’s average annual rainfall was around 880 mm, he says a rainfall
of 75 mm was enough to harvest (through a 1,000 square feet of roof
top) water that would cater to a family of four for 365 days. People can
also convert their sumps to collect rainwater, instead of corporation
water, he advises. “None of my family members have kidney stone problem
and the quality of water is so good that it has given a longer shelf
life for shaving blades,” he says.
Mr. Arunachalam,
who is passionate about rainwater harvesting, likens it to the banking
system. “My overhead tank is an ATM and the tap at the kitchen is the
debit card that can be used anytime. The sump is a savings bank account,
the overflowing water that recharges ground water is a fixed account.
In a way, it is also a community service by helping neighbours to get
good potable water,” he says.
An investment of Rs. 10,000 to Rs. 50,000 can give life-long solution for potable water, he says.
He wants Madurai Corporation to adopt the system by making it mandatory at least for high-rise apartments.
Mr. Arunachalam can be contacted over 94433 39951.