Sunday, August 19, 2012

Managing Demand Key to Nairobi’s Water Security


Nairobi ranks high on the league table of unlivable and inequitable cities globally. Inequitable because only 22% of inhabitants of the city’s informal settlements, home to over 60% of Nairobi’s residents, have access to piped water.

Unlivable because today running taps and showers are luxuries of a glorious, nostalgic past. And lets face it, Nairobi is insanitary; only 40% of Nairobi residents with access to the city’s water have access to water-water borne sewerage.

The water shortage in Nairobi is acute and chronic. The prognosis is dire; it could get worse. Here is why: inexorable demand owing rapid urban growth; declining water supplies form source areas; climate variability and change; dilapidated distribution infrastructure; and, stupefying ineptitude of the Nairobi Water and Sewerage Company (NWSC).

Historically, water management by municipal utility companies has been characterized by a ‘supply-side’ paradigm. The primary goal of this approach is to continually find and secure sufficient water to meet projected future demand. Moreover, the general level of awareness regarding water is highly variable among urban users. The culture of urban water use is such that unlimited access to high quality water is an expectation.

The long-term solutions to solve Nairobi’s chronic water problems are patently wrongheaded because they are trapped in the logic of a supply-side paradigm. For instance, a feasibility study and master plan for developing new water sources for Nairobi and satellite towns recommends groundwater development, abstraction and diversion of three rivers to supply additional water by 2017.

Why is NWSC expending vast resources to find new water supply sources when they cannot account for 40-60% of the water pumped to the city Nairobi? Regrettably, the new water supply sources will only raise the daily supply to 685,980 cubic meters per day in 2017, against a projected daily demand of 1 million cubic meters.

For nearly a decade, NWSC has handled water shortages the same way; reduce supply. They enforce, with mischievous alacrity, a punishing water rationing schedule. You would imagine that the chronic water shortage might motivate investments in water use efficiency and encourage efforts to reduce demand and consumption.

Nairobi’s water problems undermine the city’s prestige and diminish the respectability of our public institutions. Although Nairobi’s water crisis is a scourge on our national pride, it presents an opportunity to re-imagine how we think about, use water. We can take a number of steps that can transform, gradually but irreversibly, how we manage our precious but finite water resources. And we can start today.

There are literally thousands of leaks in the city water system. Plugging leaks in the water distribution system should be a priority for NWSC. New digital technology can help identify the most serious leaks.

I have argued elsewhere on this blog that new technology, low cost distributed innovations can harness new water sources, deliver phenomenal reductions on urban water demand while creating new jobs in green plumbing and ecological engineering.

Mandating the installation and use of low flush toilet would reduce water use per flush by 50%. Vacuum toilets use 0.5 liters of water per flush to transport the same volumes of human waste. Conventional flush toilets in the Kenyan market use 10-13 liters per flush, consuming nearly 40% of domestic water.

Building codes should be reviewed to require new to buildings submit water conservation plans including infrastructure and harvest and store rainwater that falls on their land and roofs. Harvested rainwater can be stored for use or returned to the ground. An ecological engineering approach through the application of constructed wetlands and wastewater aquaculture can be used effectively to treat and purify roof and urban storm runoff. Imagine how much water we would collect from roofs, city roads and other paved surfaces.

Wastewater from showers, baths, hand basins, laundries and kitchens – is relatively easy to reuse. With minimal treatment, in the form of physical filtering and settling, wastewater can be recovered and reused to flush toilets. Water quality cascading, an approach that aims to match water quality to water use, is an important demand management measure. Diversion of wastewater from hand washbasin, washing machine and showering to toilet flushing is an example of water quality cascading.

There is need for a national water efficiency authority to coordinate investments in demand management, enforce water efficiency standards and public education. Education for politicians and planners is absolutely critical because they are largely unaware of the levels of inefficiency associated with conventional supply side technologies and practices, or that demand side alternatives exist.

At a personal level, habits and practices that conserve our limited water supply must be encouraged. Reusing, recycling or reclaiming water extends our finite water resources. The less we use the more we will have in the future and bequeath posterity. Think of it as a savings account. The les you withdraw the more you save.

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