TAMIL NADU

`Only few houses have proper rainwater harvesting structures'

CHENNAI, AUG. 1. Though rainwater harvesting (RWH) has been implemented in almost all structures in the city, only few have done it in an appropriate manner, said experts at a meeting at Rain Centre, Mandavelipakkam, on Saturday.

Organised as part of a national awareness campaign supported by the Union Ministry of Environment and Forests, the meeting analysed the correct and incorrect methods of RWH and recycling of wastewater.

The Rain Centre director, Sekhar Raghavan, said the meeting was motivated by a recent survey on construction of RWH structures conducted at Gandhi Nagar and its neighbourhood.

Appropriate method

Classifying the appropriate methods in terms of four categories — their completeness, apportioning of rooftop water, design of structures and their maintenance — he listed out the observations made on RWH systems. Most people failed to harness run off water and harvested only rooftop water.

Only if both were done, could a RWH structure be considered as complete.

In many houses, the apportioning of rooftop water was not done properly. While some outlets could be directed to source and recharge wells, a few others could be directed to the sumps for storage.

Incorrect structures

Design of structures, which had a vital role in harnessing rainwater, was also found to be incorrect in many residences.

While recharge wells were unnecessarily filled with filter material, the percolation pits were dug to insufficient depth.

RWH structures should be filled with 1/3rd of filtering materials and filters need to be well designed for an efficient recharge.

Maintenance of RWH systems such as desilting and cleaning was also neglected in several residential complexes, Mr. Raghavan said.

Recycling

The vice-chairman of Alacrity Foundations, Indukanth Ragade, spoke on the cost-effective recycling at domestic level.

The water used for bathing and washing, which was 60 per cent of consumption, was sterile and could be reused for non-potable purposes. It could be directed to water semi-aquatic plants.

The excess water would be treated by soil for recharging the groundwater table.

The treated water could be arrested by laying a concrete flooring beneath the plants and diverting to an underground tank for reuse.

This process does not emit odour or attract flies and needed no maintenance, Mr. Ragade said.

The Rain Centre would inform residences at Gandhi Nagar and its neighbourhood that lacked a proper RWH system and technicians would be sent to rectify the problem.

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