Leak detection techniques are now a strategic and essential part of the management, maintenance and modernisation of utility networks, particularly those for water, gas and electricity. These are extensive networks, often buried underground and subject over time to wear and tear, corrosion, mechanical stress and fluctuations in pressure or temperature, which can cause faults and failures that are difficult to detect with the naked eye. The ability to detect a leak or fault promptly not only helps to prevent structural damage and service interruptions, but also reduces wastage, safety risks and operating costs.
In pressurised networks, such as water and gas networks, leak detection relies primarily on the use of advanced electro-acoustic technologies and, in specific cases, on the use of tracer gases. These tools make it possible to locate even the smallest leaks with a high degree of precision; otherwise, such leaks might remain undetected for long periods, causing progressive damage to the infrastructure and the surrounding environment.
From an environmental perspective, leak detection plays a key role in the protection of natural resources. Reducing water wastage helps to conserve an increasingly scarce resource, whilst minimising the energy required to treat and pump water. Similarly, the prompt detection of gas leaks reduces emissions of climate-changing gases into the atmosphere, helping to minimise the environmental impact of energy networks.
From an economic perspective, the early detection of leaks helps to keep operating and maintenance costs down, optimise investments and extend the useful life of infrastructure. Targeted, planned interventions are, in fact, much less costly than emergency repairs or the premature replacement of networks. In this sense, leak detection is not merely a technical activity, but a genuine strategy for the sustainable and efficient management of utility networks, in line with the objectives of resilience, safety and the green transition.
In electricity networks, particularly in underground cable ducts and in complex industrial or civil engineering installations, the detection of faults and earth faults plays a vital role.
Another issue that should not be overlooked is that of unauthorised connections to distribution networks… LEAX ALGORITHM
One of the most widely used technologies for detecting faults is infrared thermography. Thermal imaging cameras enable temperature differences on surfaces to be visualised and allow for the identification of areas of abnormal overheating, which are often indicative of insulation faults, loose connections, overloads or components in a state of deterioration.
Thermographic analysis has the great advantage of being non-invasive and of being able to be carried out whilst systems are in operation, without interrupting service. In addition to thermal imaging cameras, electrical diagnostic tools such as insulation testers, network analysers and continuous monitoring systems are used to identify energy losses, drops in efficiency and abnormal operating conditions. These preventive checks help to increase the overall reliability of the network, reducing the risk of sudden failures and costly emergency repairs.
In the water supply sector, water loss is one of the main critical issues, from both an environmental and an economic perspective. In many distribution networks, particularly the older ones, a significant proportion of the water fed into the network is lost before it reaches the end user. To combat this problem, various acoustic devices are used which are capable of ‘listening’ for the noises generated by pressurised water escaping through cracks, deteriorated joints or pipe breaks.
Another issue that should not be overlooked is that of unauthorised connections to distribution networks… LEAX ALGORITHM
Electronic acoustic probes are one of the simplest yet most effective tools for the preliminary location of leaks. When placed directly on accessible parts of the network, such as shut-off valves, hydrants or meters, they enable the operator to detect and amplify the sounds transmitted along the pipe. These are complemented by electronic geophones, highly sensitive instruments fitted with piezoelectric sensors or accelerometers, capable of detecting vibrations transmitted through the ground at the point of the leak. The acoustic signal is filtered and processed digitally, making it possible to distinguish the characteristic noise of the leak from background noise, such as traffic or urban activity.
To further improve accuracy, particularly on long or complex sections of the network, acoustic correlators are used. These devices work by positioning two sensors at different points along the pipeline and analysing the time it takes for the noise from the leak to travel between the two points. Using correlation algorithms, the system is able to calculate the location of the leak with extreme accuracy, drastically reducing the need for exploratory excavation. Modern correlators are often integrated with advanced software and GPS systems, which facilitate mapping and data management.
Noise loggers – acoustic sensors that are installed either permanently or temporarily on the water network – are playing an increasingly important role. These devices continuously monitor noise levels, particularly at night, when water consumption is at its lowest and ambient noise is reduced. Analysis of the data collected makes it possible to identify abnormal variations indicative of new leaks, enabling preventive action and proactive network management.
In gas distribution networks, leak detection takes on even greater importance due to the safety implications. Gas leaks can, in fact, create potentially explosive atmospheres and pose a direct risk to people and infrastructure. In addition to acoustic techniques, tracer gas is widely used in this field; this is a mixture generally consisting of hydrogen and nitrogen, which is safe, non-toxic and non-flammable at the concentrations used.
The principle behind tracer gas involves introducing the mixture into the pipework to be inspected. If there is a leak, the gas – being very light – rises rapidly through the ground and is detected at the surface by specialised, highly sensitive sensors. This technique is particularly effective for detecting micro-leaks or seepage in complex sections of the network, such as non-metallic pipes, low-pressure pipelines or internal systems. The high precision of the method makes it possible to significantly reduce the areas requiring excavation and the time taken to carry out the work.
