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eThekwini's water usage decreases

eThekwini Water and Sanitation is pleased at the drop of the city's water usage and hopes to reduce it further by implementing waste management systems.

24 February 2012 | Rianette Jansen van Vuren

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AWARE that Durban is quickly outgrowing its water supply, eThekwini Water and Sanitation (EWS) is making significant strides in containing non-revenue water (NRW).

Head of EWS, Neil Macleod, said the average monthly bulk water purchases that were steadily increasing prior to 2011, had shown definite and sustained signs of decreasing and had dropped to levels last seen in July 2007. Average daily purchases of water from Umgeni Water decreased by 50 912 kl from the 2009/10 financial year daily average.

"In the 2009/10 financial year, the non-revenue water was 37.4 per cent. During the 2010/2011 financial year, we reduced this loss to 33,2 per cent which amounted to an improvement of 4,3 per cent. Our long term goal is to reduce water loss to 25 per cent within the next eight years," he said.

To realise this long term goal, EWS put in place a proactive 17 point plan to minimize water losses and optimise service delivery to consumers. During 2011 – which comprises the second half of the 2010/2011 financial year and the first half of the 2011/2012 financial year – the replacement of aged infrastructure such as faulty water meters, the reduction of water pressure which is a major cause of leaks and bursts and the detection and repair of leaks gathered momentum.   

According to Macleod, during the financial year ending June 30, 2011, EWS commissioned 230 pressure reduction valves and seven innovative i20 pressure controllers. The pressure controllers are revolutionary devices with artificial intelligence’ to optimise the control of water pressure.

Utilising Global System for Mobile (GSM) Communication signals, the i2O controller is constantly updated with pressure information from a critical point in the zone. Using advanced algorithms, it then makes minute adjustments to a pressure reducing valve to ensure that the water pressures are kept at an optimum level at all times.

"Actively managing the water pressure translates into an ongoing reduction of water loss through leaks and burst pipes. Preliminary investigations have indicated that a reduction of 40 per cent in pipe bursts is possible. In the Durban CBD, this advanced controller was utilised to lower the minimum night flow from 599 m3/hr to 352 m3/hr that equates to almost 6 Ml/day," he said.

The design, installation and commissioning of new Pressure Reducing Valves (PRV’s) has continued into the current financial year with an overall target of reducing the average system operating pressure to 42m.

"As part of EWS’s Advanced Pressure Management strategy, 110 new pressure reducing valves will be designed, 100 new PRV’s commissioned and 30 advanced pressure control devices will be installed and commissioned during 2012," he said.

Macleod said detecting and repairing leaks had played a significant role in containing water losses throughout the 2010/11 and during the first half of the 2011/2012 financial years.

A key factor has been EWS’s use of Category B plumbers in informal and formal areas on a find and fix approach.

"During the course of the financial year, this proved extremely successful with a dramatic increase in the number of leaks repaired at a far lower cost. This activity will be continued with targets set at 4000 km of leak detection surveys and the repair of 20 000 leaks for 2012."

Billing improvements have also been high on the EWS agenda with some important new measures introduced during 2011.
Interventions such as the replacement of non-domestic consumer meters older than 10 years and the replacement of all domestic consumer meters that are older than 20 years continued. During the first half of this year, EWS intends regularizing a targeted 820 illegal connections through the Amnesty Program and municipal courts.

The installation of informal area meters remains a priority in assisting with the reduction of NRW in informal areas through the increase in billed consumption. Improvements during 2012 will see a further 400 informal area meters (also equipped with pressure reducing valves and time-control) installed.  

Macleod said regularising and registering connections from eThekwini Housing projects was another activity that would continue from 2011 to 2012.  

"The target for the year has again been set at 10 000 connections which are to be installed and registered at all new housing developments that are either underway or will reach completion in the financial year."

Macleod said during 2012 EWS would also replace and commission three custody transfer point check meters at custody transfer points to monitor the supply of water from Umgeni Water to EWS using the latest and most advanced metering technology.

"The management of the bulk sales agreement will be further improved through planned meter calibration/verification tests at a total of 20 sites. Check meters that have been installed to date have yielded encouraging results and we anticipate that the daily volume of water purchases will be reduced due to more accurate metering," Macleod concluded.

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