More than Pipe Dreams: Non-Revenue Water Solutions
By Jon Boon 9 May, 2012
Pure Technologies' Jon Boon shares their experience in tackling non-revenue water in Manila
Non-revenue Water (NRW) as the name suggests, describes the all too common occurrence of water that is lost, or unaccounted for, en route between the water supplier and the customer. As might be expected, NRW is a major challenge for water utilitity companies and governments, who are responsible for the upkeep of pipelines and is a particular headache in developing countries where technology and resources to address the problem are often limited. Such water losses may occur as result of poor utilities management including lack of accountability and governance leading to badly maintained pipes and leakages, as well illegal connections.
According to the World Bank1, the total cost to water utilities caused by NRW worldwide can be conservatively estimated at $141billion per year, with a third of it occurring in the developing world. NRW rates have long been used as a marker for the efficiency of water companies in Europe and North America.
For China, Steve Clark, the director of Sino French water suspects NRW loss rates to be above 25%.
With such a high NRW rate, tackling NRW could be the simplest route to save water and a low hanging fruit in China’s drive to improve water efficiency. Jon Boon from PureTechnolgies (Pure), one of the world leaders in the development and application of innovative technologies for inspection, monitoring and management of physical infrastructure shares with us Pure’s experience with Maynilad, a water and wastewater services provider operating 6,000km of pipelines in Manila and how technology solutions have reduced losses of millions of litres of water per day…
Maynilad Water: The issues
Maynilad Water Services (Maynilad) is the water and wastewater services provider for 17 cities and municipalities that comprise the West Zone of the greater Metro Manila area in the Philippines. Maynilad operates a pipeline network that comprises more than 6,000 km.
Reducing NRW has been a key goal of Maynilad and Pure was awarded a contract to assist the utility in reducing NRW by administering a leak detection and training program. The programme started in January 2010 and is ongoing. The programme is wholly managed by Maynilad using Pure’s equipment.
The technicalities of water loss
NRW is being addressed using a number of methods. One of the most effective has been to focus on at the trunk mains which feed the distribution system. The results achieved have mirrored the situation in other places such as Dallas2, Texas. That is, trunk mains are a major source of leakage and that by inspecting these mains high NRW reductions can be achieved.
Although the numbers of leaks per kilometre tend to increase with a decrease in pipe size; the volume lost in an individual leak tends to increase with pipe diameter. Put simply a 1% loss though a big pipe delivering 10,000,000l/day is 100,000l while a 1% loss through a pipe delivering 10,000l/day is just 100l, so a thousand small leaks in smaller pipes may be equivalent to just a few leaks in a large diameter pipe. It is not unknown for large diameter pipes to have losses in excess of 10% of the total volume carried. This means that solving problems in bigger pipes can bring huge benefits to water companies seeking to reduce costs and minimize expenditure.
The leak detection program
Sahara® leak detection system is optimal for urban centers such as Manila that have complex interconnecting trunk main networks. Maynilad has since used Sahara® combined leak detection and video inspection on its major pipeline systems.. This technology is used to detect leaks, illegal taps such as the eight shown in the picture below.
In addition, there were laterals, many of which were unknown and hence the source of large volumes of NRW. Once identified these laterals were closed allowing Maynilad to achieve major reductions in its NRW. The leaks themselves, even the big ones were often not visible from the surface even when they were very large and presumably had been leaking for long periods of time. Unknown laterals or known laterals that are supposed to be isolated, channeling water to un-accounted for clients or to neighbouring utilities, have likewise been successfully identified and located using a video camera during inspection, such laterals were a major contributor to NRW. Other water losses sources detected included services which had been illegally tapped on primary lines.
Pure’s contract’s scope with Maynilad included provision of training and the rental of two sets of Sahara equipment. This contract was signed in 2009 as part of a strategic water loss management program aimed at reducing non-revenue water. Under this contract, Maynilad engineers were trained in the use of the Sahara technology to operate the equipment in the West Zone concession. The initial contract has so far been extended three times as a result of Maynilad Water Services obtaining a highly beneficial return on their investment with a short payback period.
The leak detection program allows the client to establish the condition of their pipeline in order to optimize repair and replacement programs and maintain vital supply to customers. Since the start of the program, 264 km have been surveyed with 319 leak located and 173 illegal connections and unknown laterals identified and shut down. Total volume of water saved to date has been in excess of 110 Million Litres per Day (MLD) which is the equivalent water demand by more than 300,000 people. Reducing NRW and boosting the netwrok efficiency in this manner is a more cost effective and environmentally sustainable approach than building new reservoirs and treatment plants.
How it works
Sahara pipeline inspections are conducted while the main remains in service by inserting a sensor through a gated valve tap of 50mm or larger. The tethered cable provides a high degree of operator control with inspection results provided in real time. Sahara is a versatile tool with a variety of configurations capable of detecting leaks, providing CCTV inspection,. A small parachute uses the flow of water to draw the sensor through the pipeline. The sensor is tethered to the surface, allowing for real-time results and maximum control and sensitivity. The surface tracking device allows the position of leaks and other pipeline features to be located to within 450mm. Depending on pipeline features and flow velocity, Inspection distance can go up to 2km. Video is run concurrently with the leak detection inspection, which allows CCTV inspections on pipelines while they remain in service, Video is used to assess the conditions of pipeline interiors, locate known features with unknown locations, and locate unknown features including unknown laterals and line valves along the inspected pipelines.
More than just water leaks
The Sahara leak detection system is also an accurate tool for detecting pockets of trapped gas in large diameter water and wastewater mains. Such gas can create air pockets that adversly affect water pump efficiency. It is effective in pipelines of all materials and diameters above 300mm where other technologies are less effective. Sahara is a critical component of assessing pipeline conditions and water loss management programs for utilities throughout the world and has greatly contributed to Maynilad’s NRW reduction program.
1World Bank, 2006. The Challenge of Reducing Non-Revenue Water (NRW) in Developing Countries How the Private Sector Can Help: A Look at Performance, Water Supply and Sanitation Board Discussion Paper Series No.8
2 City of Dallas Leak Management Overview Global Leakage Summit London 2010Randal Payton, Sr. Program Manager Dallas Water Utilities
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