HOLES IN THE BUCKET - FINDING LEAKS IN THE DISTRIBUTION NETWORK
Leakage is a major issue to the water industry. In the UK almost 3 billion litres of water leaked from the water distribution network each day from April 2019 to March 2020 according to Water UK fi gures. This is equivalent to 1,182 Olympic sized swimming pools of water daily. Each UK water company has its own leakage target based on how much it costs to reduce leakage in their distribution area and how much the saved water from reducing leakage is worth in fi nancial terms, environmental terms and to meet customers’ expectations. Leakage targets are approved by the regulator Ofwat and set at levels to keep water bills affordable. Targets are not the only driver for reducing leakage though.
Let’s take Anglian Water (AW), the largest water and sewage provider in England and Wales, as an example. The area supplied by AW for example, has experienced large economic and population growth; 500,000 more households are supplied now compared with 1989. This growth is continuing and an estimated additional 104 million litres per day of water is required by 2045 (Figure 1). However, this area in the East of England already experiences pressures on water resources, for example from irrigation for farming, and there is little capacity for additional abstraction. It is a very dry region - at some points in the year, rainfall levels are comparable with Jerusalem. If water supply is not increased to meet demand and to sustain growth, then customers would likely experience water use restrictions, low pressure problems and supply interruptions. Anglian is currently working on a strategic pipeline interconnector project to link water sources in the North of the region into the supply network, and additional surface water reservoirs in the East of the region, but leakage reduction is also key to meeting demand.
Anglian Water has an ambitious leakage reduction target of 52% compared with 1999 levels of leakage. Anglian Water engineers repair more than 45,000 leaks in the network each year, and there are 3 year rolling leakage reduction targets to keep the company on track. Another driver to reduce leakage comes from customer perception. “Our customers view leakage as a strong disincentive to adopting more water effi cient behaviours”, explains James Hargrave, Regional Leakage Operations Manager at Anglian Water. So, if Anglian Water can show that they are meeting leakage reduction targets this should help incentivise customers to also do their bit to save water at home. But how else can the steep target of 52% reduction compared with 1999 levels of leakage be met by 2045? What technologies exist to help meet this challenge?
Already 7,000 hydrophones fi xed into the network cover about 15% of the supply network, to help detect leaks. Plus monitoring data from more than 250,000 smart water meters has also directly identifi ed leaks. DMA fl ow is closely linked with seasonal patterns of water use and weather, with the highest
peak in August 2021 (Figure 2). The fl ow peaks that would historically have prompted leakage investigations can therefore be explained as variation in consumption or use, which helps to avoid unnecessary call out work. Importantly, genuine leakage can be correctly identifi ed. “Where night use differs from Base Net Flow, we can infer leakage and target leak repair work effectively,” explains James Hargrave.
IET JANUARY / FEBRUARY 2022 Figure 1: Area served by Anglian Water with projected increase in demand
for water from 2016 - 2045
Figure 2: An example DMA with 100% smart meter coverage (© Anglian Water, 2021).
Figure 3: Intelligent valve system (© Oxford Flow, 2021)
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