The addition of nearly 3 million people in the last decade has had repercussions on the sanitation infrastructure and services of the city, feels water expert S. Vishwanath

The census 2011 figures suggesting a population of nearly 8.50 million for the Bangalore Mahanagara Palike area comprising 198 wards has a wake-up call for the water supply challenge but has an even bigger alarm for the sanitation and sewerage challenge. The addition of nearly three million people to the city's population in the last decade has repercussions on the sanitation infrastructure and services as well. As of now the Bangalore Water Supply and Sewerage Board is rolling out a mega project to expand the trunk lines as well as to increase sewerage connectivity, yet the fact remains that less than 50 per cent of the city's households are connected to a broken network which performs abysmally in collecting, conveying and treating waste-water.

The peripheral areas of the city are the ones which show most of the growth with the city centre marginally increasing in population due to densification. Most of the individual homes, apartments and layouts coming in the periphery will have to make do for their own sanitation systems.

The larger apartments and developments have to necessarily go for wastewater treatment plants, smaller layouts and individual homes will go for ‘on plot' sanitation systems. This essentially consists of a large soak pit usually lined with concrete rings 3 ft. in diameter and about 20 ft. deep.

All wastewater from the house is led into this pit which then leaches into the ground. Once the pit is filled the house owner generally calls for a ‘honey-sucker', the yellow coloured pumping trucks, which vacuum suck the pits and empty it for reuse. A flourishing business satisfying the consumer has emerged around this service. This has helped eliminate manual emptying of the pit, a degrading business, as well as put the manure to productive fertilizer use.

Other alternatives

Other ‘on-plot' systems that can do well are the ‘twin leach pits' for the toilet. A system of two pits which can be alternated in use and once full one pit is allowed to dessicate and compost the manure for safe disposal. The twin leach pit can be in tandem with a soak pit for grey water from the bathroom and kitchen to soak into the ground.

Slightly more sophisticated systems like the septic tank and the DEWATS are also being used, though not in the numbers such as the single soak pit.

As investment in sewerage systems are lumpy and not incremental, there will always be developments will have their own on plot systems. A way must be found to incorporate safe systems of sewage management and encourage good practices such as that of the ‘honey sucker'.

A mixed bag of on-plot sanitation and wastewater treatment systems will have to be managed.

The quality of groundwater, soil, surface water and indeed the overall environment depends on how multiple solutions are found to manage waste streams safely and hygienically. An exploding urban system is a complex challenge with multiple layers of solutions.

Each needs to be optimised and integrated into an overall framework. Only then can we have a safe, sustainable and healthy city.

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