Reuse greywater wisely

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

January 23, 2015 04:30 pm | Updated November 13, 2021 10:49 am IST

Cleanse used water from the kitchen by diverting it to a clump of bananas.

Cleanse used water from the kitchen by diverting it to a clump of bananas.

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

Top News Today

Sign in to unlock member-only benefits!
  • Access 10 free stories every month
  • Save stories to read later
  • Access to comment on every story
  • Sign-up/manage your newsletter subscriptions with a single click
  • Get notified by email for early access to discounts & offers on our products
Sign in

Comments

Comments have to be in English, and in full sentences. They cannot be abusive or personal. Please abide by our community guidelines for posting your comments.

We have migrated to a new commenting platform. If you are already a registered user of The Hindu and logged in, you may continue to engage with our articles. If you do not have an account please register and login to post comments. Users can access their older comments by logging into their accounts on Vuukle.