Tanks of Bangalore are generally characterised by indiscriminate growth of weeds, pollution on account of eutrophication and a chronic lack of funds. Wetlands across the world have proven to have a definite role in cleansing function.

The variety of animals and plants dwelling in a tank ecosystem has contributed to a cleaner and vibrant water body. Researchers keen on evolving sustainable ecological systems have over the years come up with several models that to a large extent eliminate the use of chemicals as well as complex technologies.

The “Living Machines” model is one of the fast growing ecological methods to manage water bodies for the purpose of tertiary sewage management. This model thrives on living organisms - microorganisms, fungi, animals, plants and birds - that work in tandem to facilitate effective wastewater and sewage treatment.  Living machines have found to be effective and successful used in the U S, Mexico, Great Britain and Canada.

Living machines symbolise the perfect cooperation between different organisms with each one having a defined role.  The plants, apart from facilitating gaseous exchange, act as filters of suspended solids, and also provide the threshold antibiotics to regulate pathogens within safe levels. Bacteria, snails and shrimps breakdown the dissolved or suspended solids into much simpler components.

The bacteria process the toxic and heavy metals to simpler, harmless components.  The snails are effective environmental indicators of influx of toxic chemicals. The resultant recycled water is usually much cleaner.

Exposure to UV light further improves the quality of water. One veritable advantage of the living machines model is total absence of the use of chemicals. Weeds have an important role of being food for a lot of aquatic birds.

The A T Ramaswamy Panel on Land Encroachment, during a very recent visit to six tanks, identified encroached land worth Rs 260 crore. Bangalore is a city of tanks. Though much less in numbers now, we do have about 60-70 still-functioning tanks at various degrees of deterioration. If the encroached land is reclaimed from all these different tanks, there is enough corpus to protect and maintain our tanks for posterity.

There is an overwhelming feeling among our planners that our water bodies must have water 365 days.
Bangalore is characterised by semi-arid climate. As a result, impounding rain water through many small tanks in various places is an effective way to save water apart from rain water harvesting by individual houses and apartment buildings. During the non-monsoon period, the tanks may dry up.

This transition between no-water and water is part and parcel of the bioregional complex. The moment environmental managers assume and visualise the water bodies as lakes, filled with water on all the 365 days; there is no space to accommodate the temporal activities, culture and livelihood. This model goes against the very purpose and basis of making these tanks.

It is time the citizens of Bangalore confront any developmental model that ignores the realities and needs of sustaining ecological integrity of our ecosystem. Let's at least preserve the tanks as relics of our rich past, rather than the way lakes are portrayed in our cinemas.

(The writer is a teacher of environmental management at Mallya Aditi International School.)