Case Study: LeakNavigator Delivers 80% Conversion Rate for Southern Water

Southern Water, which serves more than four million customers in the water-scarce south-east of England, is working towards a 15% leakage reduction by 2025, writes Tony Gwynne, leakage solutions director, Ovarro. The water company’s Water Resources Management Plan 2024 sets out long-term plans to more than halve leakage by 2050 through a combination of new technologies and enhanced monitoring, using tools such as acoustic sensors and digitalised management systems.
In November 2020, Southern Water began a project with technology company Ovarro to undertake targeted leakage reduction in approximately 40 district metered areas (DMAs) across its region of Kent, Sussex, Hampshire and the Isle of Wight.

Fully-managed fixed network

As part of its commitment to use new technology to find leaks, Southern Water became one of the first utilities to deploy Ovarro’s LeakNavigator, the UK’s first fully-managed, fixed network leakage service.

The LeakNavigator package comprises acoustic dataloggers from Ovarro’s Enigma range, a cloud-based analytics platform and the company’s in-house leakage expertise. Ovarro analysts plan out a fixed network of acoustic loggers on behalf of water companies, support the installation process, analyse the data to pinpoint leaks, raise points of interest (POIs) and assign them directly to technicians.

To start the process, Ovarro’s analysts undertake a pre-assessment of each targeted DMA, establishing the most suitable logger type and install locations. Logger installations are typically carried by the utility’s leakage contractor, although Ovarro can manage the process if required.

Once the loggers are in operation, data is fed into the LeakNavigator analytics platform, LeakInsight, which will generate POIs based on the overnight correlations. Filters can be applied so the platform removes noise such as electrical interference, pressure reducing valves and mechanical water meters. High priority ‘hot spots’ can also be flagged up.

Ovarro’s analysts review each POI that has been generated, checking for consistencies in the data. If the data indicates the strong likelihood of a leak, analysts will assign the POI to leakage technicians via a mobile app. A technician will visit site, confirm the location of leaks found, and raise a job for the repair. If no leak is found, analysis and communication continue via the app until a conclusion is reached.

Ovarro sends regular reports and POI trackers to the customer and its leakage contractor. The platform is flexible, meaning any part of the process can be tailored for individual companies.

For Southern Water, approximately 1,650 correlating acoustic loggers were installed across the company’s region. Of these loggers, 1,500 were the model Enigma3-BB, a hydrophone sensor, and the remainder were the model Enigma3m, an accelerometer sensor.

The Enigma3-BB was selected as the primary logger due to ease of deployment – the device is installed in a property meter box chamber, which requires no work in the highway, and provides more access point to the network.

The Enigma3-BB sensitive hydrophone is also proven to be effective in picking up leak noise on plastic pipes – an enduring challenge for water companies, as sound does not travel well on plastic. As more ageing metal pipes are replaced with plastic, the scale of this challenge is set to increase.

Conversion rate of 80%

In the early weeks of the project, approximately 12 leaks were detected per month. Knowing the figure could be improved, Ovarro analyst Chris Mould reassessed each DMA and set specific individual filters using the LeakInsight software.

Additional training in the system and POI follow-up process was also given to leakage technicians onsite. Following the training, technicians began to find more leaks, much faster – rising from around 12 per month to approximately 130 – and they gained greater confidence in the accuracy of the POIs.

Up to July 2024, a total of 1,170 leaks and 66 burst mains had been found. An overall conversion rate of 80% was recorded for category 1 alerts, for which the data indicated a strong likelihood of a leak being found. Leakage in 35 of the DMAs had reduced, with an overall reduction of 51 cubic metres in water loss across all DMAs. This equates to 204Ml/d of water being saved every month. Targets in 16 DMAs had been met, with the project ongoing.

Notable successes include:

In April 2024, LeakNavigator detected two main bursts in one DMA in the town of Andover in Hampshire, where leakage had been increasing for approximately 12 months. Earlier attempts to pinpoint the leak had proved challenging – in part, due to a pressure reducing valve emitting constant sound and an oval-shaped water main pipeline that reverberated all sound waves.

On following up the POIs, with close guidance from Ovarro’s analysts, technicians found two large bursts, one on a plastic pipe and one on metal, both likely to have been running since at least January 2024. Following repairs, the nightline figure for the DMA reduced by 13.5m3/h. Using previous methods of leak detection, the leaks were likely to have continued to go undetected until they became visible at the ground’s surface.

In June 2024, two further large leaks were picked up by the system, both on communication pipes. The first repair saw the nightline reduce from 15 cubic metres per day to nine. The second repair brought a further reduction which took the DMA nightline down to 3m3 per day.

Throughout the project, Ovarro analysts have maintained constant communication with Southern Water’s leakage managers and contractors.

Ovarro leak analyst Chris Mould said: “Key to the success of this project has been close communications between Ovarro, our client Southern Water and the technicians who are following the LeakNavigator process in the field every day.

“Their ongoing feedback has helped us enhance the process and Southern Water has been supportive of trialling new approaches. As a result, the system is running with high efficiency, tailored to the client’s needs, and is producing excellent results.”

Phil Tapping, regional operations leakage manager at Southern Water, said: “We are aiming to reduce leakage by 53% by 2050 – a target greater than the 50% reduction set by the government. New technology, like LeakNavigator, is a key part of our strategy.

“Having used Ovarro leakage products for a number of years, we were confident that LeakNavigator would deliver good results in the DMAs we were targeting. After some initial training and guidance, the overall end-to-end process was straightforward, and we are pleased with the outcomes to date. As a result, we plan to continue to use LeakNavigator in AMP8.”

Source: Ovarro Ltd.