What is Leak Detection?

Water losses can occur at many points within the water supply system. Physical losses occur mostly in service connections in our country. It is generally used in urban infrastructure works (wastewater collection, road paving, natural gas connections, telephone, electricity, etc. connections), excavation, etc. During operations, service connections are damaged and leaks begin to occur. Damaged service connection pipes cannot be repaired at the desired level by the companies that perform the related infrastructure activities. As a result, leaks with relatively low flow rates begin at service connections that are not well repaired, and large amounts of water are lost over many years. Leachate water often does not come to the surface at the junction points where leakage occurs, and is destroyed by infiltrating underground.

Leaks often occur in plastic (PVC) water pipes used in water distribution networks and kept under the sun for a long time. Leaks start from the cracks in the pipes and water losses continue for many years until the leaks are noticed and repaired. In addition, losses may occur in old pipes, various valves and connections in supply and distribution lines.

Active leaks should be detected and leak points on the line should be repaired. By navigating the network over the numerical data at hand, Leakage points should be determined by making acoustic listenings, especially during the hours when the noise is low. Repairing the detected leak points is an important factor in reducing water losses. It is a process that should be applied periodically.

Characteristics of Leaks

Searching for, identifying, locating and repairing leaks consists of three stages. These stages can be defined as Awareness-A, Location-L and Repair (Repair-R) and ALR for short. In this approach, leaks in pipes, overflows in tanks or losses at different points occur in three stages:

• Time to awareness - the time it takes for management to become aware of the leak.
• Locating time - the time it takes to locate the leak.
• Repair time - the time required to repair or repair.

The longer the time spent by the administrations to become aware of the water loss/leakage, locate it and finally repair it, the volume of water lost also increases. It can be weeks or even years before a leak going underground is noticed. Therefore, the time to detect leaks, locate and repair leaks should be reduced within the water loss reduction strategy.

Types of Leaks

It is crucial for water utilities to understand the occurrence of the different types of leaks within their systems, and to evaluate the leak flow time and ALR processes as well as the total volume of physical water losses. Types of leaks are listed below:

• Reported outbreaks – They are visible and often quickly reported by the public. Awareness time for such outbreaks is short.
• Unreported eruptions – Usually occur underground and do not rise to the surface. It is often discovered in leak detection studies and has a long Time to Recognition.
• Background leak – Caused by a combination of very small leaks. Detection and repair of such leaks one by one is both difficult and costly.

Active leak control is a vital practice for cost-effective and effective water loss management. Ground microphones electronically amplify the sound/noise caused by the leak. These devices can be mounted for use in contact or tracking mode. The contact mode is used for listening to connectors and is similar to electronic listening sticks.

Monitoring mode is used to search for leaks in pipelines between fittings. In this method, the ground microphone is placed at certain distances on the pipeline and the changing noise level is monitored as it approaches the leak point. Once the presence of a leak has been determined by acoustic loggers or a leak noise correlator, the site team can locate the leak point.