The rage these days among urban planners in India with regard to used water management is to implement city wide sewerage systems with the collected used water to be treated in Sewage Treatment Plants before release into water bodies. This is without the basic understanding that sewerage systems require water supply at 150 litres per capita per day which is not there even in the large metros in this country let alone in smaller towns. The capex and opex of these centralised systems is huge and beyond the financial capabilities of urban local bodies and so in most cases they are malfunctioning even where they have been implemented at huge costs. In fact the financial and operational sustainability of these centralised systems is now endangered even in the developed countries despite their greater resources. Listed below are the problems that centralised used water management is facing in these countries.
1. Outdated Combined Sewer Systems: Many cities rely on combined systems that carry both stormwater and raw sewage in a single pipe. During heavy rainstorms, the volume exceeds capacity, forcing utilities to trigger raw sewage overflows into water bodies to prevent water logging.2. Intense Climate Events: More frequent and severe storms driven by climate change overwhelm the systems faster than historical design standards ever anticipated.
3. Aging and Deteriorating Assets: Much of the underground piping, concrete structures, and mechanical pumps have exceeded their intended service lives, suffering from internal corrosion, structural cracks, and root intrusion.
4. Underinvestment and Maintenance Backlogs: Decades of deferred maintenance and tight municipal budgets have left public utilities struggling to inspect, clean, or replace kilometers of hidden underground sewers.
5. Modern Contaminants: Contemporary waste streams include difficult-to-break-down pollutants like microplastics, persistent pharmaceuticals, "flushable" wipes, and high volumes of fats, oils, and greases (FOG) that clog or pass through traditional treatment processes.
6. Huge Operating Costs: Extensive use of energy to both pump the sewage and treat it has pushed up operating costs apart from exacerbating climate change.
Consequently, even in developed countries the stress now is on localised, household and community based circular used water management and reuse using natural solutions which are cheap. However, we here in India are still labouring under a colonial hangover and opting for centralised systems.
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