Water: The 40% Syndrome

By K. Murali

The present water stress will be carried over to next year if there is no bumper rainfall during the course of the next wet season. A normal rainfall next year will not do

In 1999, Mauritius faced one of the severest droughts in its history. Due to a deficient rainfall, the impounding reservoirs were not topped up and boreholes went dry. As a result, the population was subjected to a severe regime of water cuts. Agricultural production was affected and industrial output suffered. The economy took a beating.

One would have thought that the lessons had been learnt. Clear-cut policies, together with a vigorous implementation of projects to minimise the effects of at least one single dry year were expected from the authorities. However nothing significant has been done. Today, at the dusk of the first deficient rainfall season since 1999, we are faced with a nightmarish scenario of water not flowing from the taps for relative long periods — two days, at a stretch, it would seem in some places.

It is important to understand how we have come to this situation before discussing solutions to the present problem.

Since 2000, all successive governments have focussed their attention on one single objective towards improving the potable water supply situation. Their credo has been that the water losses in the distribution network is of the order of 40% and by reducing this amount more water would be available at the consumer’s end. The population would thus benefit from round-the-clock water supply, delivered at a satisfactory pressure. In this they have erred.

The figure of 40% first came in the picture in 1992 when the MMM wanted to oppose the construction of the SAJ Dam. The World Bank was called upon to submit a report to comfort the position of the MMM. Such a report was duly submitted and the advice of the World Bank was that since water leakage in the Port Louis Water Supply Zone was estimated to be of the order of 40%, it was more economical for the government to put its resources into the repairs of leaks and bring down the leakages. With resulting savings there would not be any need to construct the SAJ Dam. Based on this report, Sir Anerood Jugnauth wrote to the Japanese government, thereby putting a halt to the SAJ Dam project.

Since then successive governments have stuck to the figure of 40%. In it they found an easy solution to the water problems of the country. By reducing the 40% leakages in the CWA water network, they thought, all our water problems — whether low pressure or water cuts – would be solved. And, irrespective of the government in power, year in year out, the figure of 40% has remained rock steady. This, in spite of millions of rupees being spent in leak detection and repairs.

Meanwhile the water supply situation kept deteriorating to reach its present level. Nowadays areas, which used to enjoy a regular 24-hour water supply, are subjected to water cuts and regions that were subjected to water cuts face presently an irregular water supply.

To understand why the objective of bringing down the supposed 40% water leakages has failed to improve the water supply it is important to take a close look at this figure and to understand the realities of the water supply network of a country like Mauritius.

It is important to understand that it impossible to eliminate all real losses of water from a distribution network. Some losses are unavoidable. Amongst these we have leakages that are too small to be detected; there are also losses which would be uneconomical to repair. An estimate of this figure, known as Unavoidable Real Loss (URL), provides a key element as to the target to be achieved in a Loss Reduction Exercise.

The breakdown of the 40% non-revenue water in a distribution network is made up as follows:

  1. Unbilled Authorized Consumption — which includes water used for fire fighting, free water distributed at standpipes, or provided to religious institutions;
  2. Apparent Losses — which covers illegal connections, water pilferage for the purpose of selling water, metering inaccuracies like malfunctioning water meters, inefficient billing methods and water meter misreadings; and
  3. Real Losses – which comprises leakage and overflow from reservoirs and leaking distribution mains up to the meter of the consumer.

The table below indicates Non-Revenue Water for some Asian and African cities across the world:

City % of Non-Revenue Water
Osaka 7
Hong Kong 25
Karachi 30
Ho Chi Ming 38
Kuala lumpur 43
Jakarta 51
Delhi 53
Gaborone 20
Port Louis 45
Maputo 34
Windhoek 11
Mbabane (Swaziland) 32

Source: Loughbourough University

In Mauritius, an acceptable figure for non-revenue water would be of the order of 25%. The target therefore is to reduce the non-revenue water rate by 15% to 25%. This can be achieved in the medium term mainly by

  1. replacement of old and poorly laid pipelines;
  2. replacement of existing old meters, and
  3. control Unbilled Authorised Consumption.

Bringing down the Unaccounted For Water rate by 15% will at best alleviate the difficulties of consumers but will not solve the problem of increasing water demand in Mauritius.

It is therefore clear that for the past two decades those responsible for the distribution of potable water in Mauritius got their priorities wrong. Instead of putting all their eggs in one basket in trying to bring down the non-revenue water, they should have focussed primarily on capacity building of our storage reservoirs albeit at making an effort to reduce the level of water losses in our distribution network.

Clearly the CWA is not responsible for the present état des choses. The Central Water Act defines the duties of the CWA. It is responsible for the control, development and conservation of water resources and the treatment and distribution of water throughout the island. With the setting up of the Water Resources Unit, the CWA is now only responsible for the treatment and distribution of potable water for domestic, commercial and industrial usage. It operates under the aegis of the Ministry of Energy and Public Utilities. The Central Water Authority Act defines clearly the responsibilities of each and every stakeholder in the provision of potable water to the population. CWA is an executive arm and nothing else.

The construction of Bagatelle Dam will only be part of the solution. The South, the Central Plateau and the Northern plains will still be left out from a durable solution to their water supply problems. A new mindset is required and massive investments need to be mobilised if the government is to fulfil its stated promise, as per the CWA Mission Statement which is to secure and provide a sustainable water supply service of appropriate quality at an affordable price which meets the growing needs of the people and to support the economic development of the country.”

The CWA has to be made aware of two dangers, collateral to the present dry spell, lurking ahead.

A River Bassin Simulation exercise for the forthcoming wet season, starting December 2011 and ending May 2012 indicates that, subject to a normal rainfall (mean of the last ten years) at this time next year Mare aux Vacoas will be filled up to around 60% of its capacity, as compared to a normal of 85%. Therefore the present water stress will also be carried over to next year if there is no bumper rainfall during the course of the next wet season. A normal rainfall next year will not do.

Second, the regular interruptions of water in the distribution mains give rise to a phenomenon known as Water Hammer. This phenomenon creates havoc in a distribution network, damaging old pipes and jointings. What is certain is that the millions of rupees spent in the non-revenue water exercise in the Mare aux Vacoas areas will be lost. It is anybody’s guess, including the Singaporeans, as to what the new non-revenue water percentage will be after the dry spell is over.

In the coming months, the men and women at the CWA will have a difficult and uphill task in front of them. They need the support of one and all if they are to be see us through the difficulties facing us. This is certainly not the time to engage in a blame game.


* Published in print edition on 3 June 2011

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