Chennai

A guide to recycling greywater in your backyard

In these tech-driven times, effectiveness is often equated with complexity; and solutions that are simple and “reek” of tradition are met with scorn. Should we avoid nature-based greywater recycling, just because our great-grandparents practised it in their backyard, with only the soil and a few plants as tools?

These “tools” have not lost their cutting edge with time, and the method is as good as ever.

Urban environmentalist Indukanth Ragade, 82, has been promoting nature-based greywater recycling for over two decades. His book Self Reliance in Water, published in 2005 is a practical manual for urban citizens for using water wisely and achieve self-sufficiency in water. In the book, he presents in detail greywater recycling methodology adopted for today’s situation and involving only usage of water-loving plants, soil and sunlight. He misses no opportunity to publicise the method in the media and in workshops relating to water.

The concept

“Rewind a couple of decades, before the rise of vertical living, when more land was available, water used in the kitchen and rich in organics were sent to a clump of water-loving banana plants. As this water percolated down the soil, the plants and the soil cleaned the water. The water used for bathing and washing of clothes containing much less of organics irrigated the plants in the garden,” says Indukanth Ragade.

Since only limited soil space is now available, Indukanth Ragade ignored the kitchen outflow amounting to 10-15% of the total usage and applied the same method on the 60-65% used for bathing and clothes washing as these contained only micro quantities of organics and could be cleaned with one third the soil area needed for the kitchen outflow.

The misconceptions

Many people are scared of the “chemicals” in soaps and detergents. Their fears are unfounded, says Indukanth. “What people don’t realise is that 1. Both these are sterile and will not cause any illness to our bodies. 2. Both contain a mix of salts and organics in micro quantities and while the organics are removed by the plants and the soil, the salts are harmless. A simple calculation will show how safe the whole process is: A 100 gram toilet soap bar will easily last for at least one month for one individual. Assuming a conservative usage of only 15 litres per bath, 450 litres of water will have been used in one month and 95 % of the organics are consumed by the plants and the soil and only a miniscule amount of salts originally present in the bar will still be there. This water, containing just a few grams of salt in 4.5 lakh g is practically purer than even rainwater except for the organics,” says Indukanth.

The process

“Water loving plants such as Canna indica, Hidechium (Ginger Lily), Heliconium (any variety) or Cyperus or Banana are planted on porous garden soil and watered with fresh water till they stabilise and then the used water should diverted on it. The treated water percolates into the soil, gets fully cleaned and augments the shallow water table. The soil bed has to be uniformly level so that the full soil area is available for the cleaning.”

The Cannas will grow tall, fed by the phosphates in the detergents and beautify the garden with their lush foliage and lovely flowers. The same happens with the other plants also. Indukanth particularly stresses that there will be no smell and no generation of mosquitoes. Only 2.5 sq. ft. of porous garden soil per individual in any shape will suffice, says Indukanth.

“In large complexes and gated communities, a bathtub-like set-up (as shown in the sketch), has to be set up and the treated water collected in a sump and taken to the overhead tank. If builders provide a versatile three-compartment overhead tank (as shown in the sketch), it can be used safely for flushing and gardening purposes. Excess water can be put into the soil. If there is a well in the premises, the treated water fully cleaned by the soil will reach the well for all uses. It will reach the borewell also if its casing pipe has slots in the shallow depths,” says Indukanth.

A guide to recycling greywater in your backyard

A guide to recycling greywater in your backyard

Indukanth rues the fact that large complexes and gated communities needlessly poison 60-65% of sterile used water with 35-40 % of poisonous sewage and then treat the trebled volumes in sewage treatment plants which are expensive to install and to run. If only they provide dug wells or slotted borewell pipes and treat the greywater by his method, not only will they avoid this unnecessary expenditure but will also get 60% of that water for all uses by providing a versatile three-compartment (as shown in the sketch) which can store and supply three different qualities of water.

The maintenance

Canna plant beds need minimum maintenance. All they need is adequate sunlight and pruning once in six or eight weeks.

The benefits

According to Indukanth, treating greywater will reduce the pressure on sewage treatment plants (STPs). Besides, the plant-based water treatment is a chemical-free and cost-effective method. “The city lacks a proper sewage management system and the STPs are unable to withstand the volume of sewage. Gated communities should also recycle greywater using the natural filtration method instead of diverting it to the sewage treatment plants. Greywater should not be mixed with sewage that carried faecal matter. If greywater is treated separately, the residents can reduce the STP running capacity and cost,” he says.

For more details on the greywater recycling system, email Indukanth Ragade at isragade@yahoo.com

(The illustrations of the greywater treatment bed and the three-compartment overhead tank are based on sketches presented in Indukanth Ragade’s book ‘Self Reliance in Water’.)

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Printable version | Oct 26, 2020 4:17:47 PM | https://www.thehindu.com/news/cities/chennai/a-guide-to-greywater-recycling-in-your-backyard-with-canna-plants/article28319205.ece

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