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Reuse greywater wisely


                                                                                                                The Hindu, New Delhi, 23rd January, 2015

 

Indukanth Ragade

 

Treating greywater rather than transferring it to an STP has numerous benefits, says Indukanth Ragade

 

In the last decade, Chennai’s suburbs have seen the rise of individual houses, small and big apartment complexes and large gated communities. These areas lack sewage disposal facilities and the government has paid little attention to infrastructure development here.

 

The lack of adequate sewage disposal mechanisms give rise to numerous issues; problems related to sewage arise due to two reasons. Earlier, only the sewage went into the septic tank but today, all the used water goes into the septic tank, thus increasing its load. Secondly, effluents from the septic tank used to seep into the soil and were cleaned by soil bacteria. But, today, in large complexes, all the used water goes into the STPs (sewage treatment plants).

 

This treated water should be used for flushing purposes only after it has passed through a sand filter or an oli-electrolyte filter. Even after using the treated water for flushing and gardening, the excess volume that remains is sent out in tankers for disposal. Unfortunately, in some cases, since the cost of running an STP is high, the sewage itself is sent out in tankers, which dump it in the nearest water body.

 

In many small complexes, builders divert the greywater (water used for bathing, clothes washing and cooking) into one or more soak pits. These pits are unable to handle the load and the water stagnates.

 

What people need to understand is that greywater is of good quality and that transferring it to the STP results in it being mixed it with sewage (30 to 35 per cent). This large percentage of sterile water gets poisoned.

 

If this greywater is treated and put back into the soil, it would be beneficial at many levels.

 

The load on the septic tank will be substantially reduced, water will not stagnate in soak pits, and in large apartment complexes, the STP capacity will be reduced by half to provide substantial savings in running costs. The shallow water table will be recharged and thus provide sustained water security.

 

In earlier days, water from the kitchen was diverted to a clump of bananas that cleansed the water.

 

This water then travelled across the soil and reached the dug well. The greywater went into the soil, and reached the dug well after being cleansed.

 

Such a cyclic route for water movement can be brought back even in today’s environment by an adaptation of the traditional cleaning process in order to provide considerable water security to every household.

 

This is the first of a three-part series on greywater recycling. Mail the writer at isragade@yahoo.com

 

http://www.thehindu.com/features/homes-and-gardens/green-living/reuse-greywater-wisely/article6815151.ece