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Case Study

Metropolitan Milanese, Italy

Metropolitana Milanese (MM) manages the integrated water services for the City of Milan, which has more than 2,295 kilometers (1,430 miles) of pipeline in their network.  MM identified a critical transmission main as a priority for inspection, and proactively assessed a nine kilometer section using the SmartBall inline leak detection tool.  The Assiana Linate Transmission Main was selected as a high value main due to its location in the heart of Milan. A rupture would prove to be costly and disruptive to the city, and Metropolitana Milanese had no prior condition information on the main’s integrity.

Project Details

SmartBall® Inline Leak Detection
Pipe Material
Inspection Length
9 kilometers (5.5 miles)
1200mm (48-inch)
Transmission Type

Project Highlights

leaks in 9km identified by SmartBall® inspection

Inspection identified high concentration of leaks in specific zones

Program costs expected to be repaid in 3 years from water savings


Assessing the condition of buried infrastructure can be challenging and difficult to predict. Traditional belief dictates the condition of the pipe is directly associated with its age, however extensive field work shows this is not always the case. One-hundred year old pipes can be dug up in like-new condition, and newer pipes can show extensive damage due to operational, environmental, and installation factors. While the Assiano Linate Transmission main, a 1200mm steel transmission main situated in the heart of Milan, was installed in 1982 and therefore is not particularly old, its important nature to the network made it a priority for assessment. Reducing Non-Revenue Water (NRW) is a major concern for municipalities and a proactive approach to pipeline inspection is critical to managing investments.


Metropolitana Milanese proactively assessed a nine kilometer section of the Assiano Linate Transmission main using the SmartBall leak detection tool. This technology was chosen to allow the transmission main to remain in operation during the inspection, a critical requirement due to the networks served by the main.

The tool is a free-flowing leak detection platform that operates while the pipeline remains in service. It is capable of completing long inspections in a single deployment and is equipped with an acoustic sensor that identifies acoustic anomalies associated with leaks and air pockets. The acoustic signature is then analyzed to determine if it is a leak, air pocket, or an external noise.

Identifying leaks small or large contributes to maintaining the condition of a transmission main. In metallic pipe materials, a catastrophic failure is often preceded by a period of leakage, so identifying and repairing leaks can help to reduce water main failures, as well as reduce Non-Revenue Water loss not detected in water balances.


The SmartBall inspection identified 23 large leaks within 9 kilometers of pipeline inspected. One area of high leak concentration detected 8 leaks in a short 240 meter section. Although Metropolitana Milanese chose a low resolution tool for their assessment program, the concentrated location of the leaks resulted in an accurate condition assessment by finding the weak link in the transmission main.

While many leaks were detected during the inspection, because the overall flow of the main is high, the leakage was undetectable with traditional metering equipment. However, the potential savings from the leak detection program are significant enough to have a positive impact on the city’s Non-Revenue Water Program, and its finances.  Although the production cost of water is relatively low, the expected savings in water loss from repairing the leaks will pay back the costs of the project in approximately three years, including the cost of repair to the damaged section.

Furthermore, the results indicated that limited portions of the main have damage while most of the pipeline appears to be in relatively good condition. This gives a targeted area for repairs without the need to dig up large sections of the pipeline – a costly and time-consuming process.

By determining the specific locations of leaks on the Assiano Linate Transmission Main, Metropolitana Milanese will be able to reduce its NRW and has gained a better understanding of the overall condition of the pipeline. This will aid in future capital planning and will also provide a valuable study into determining the external factors that might be causing the leakage.

Focused repair works for the leaks will allow the utility to extend the life of the pipeline and reduce water loss, thus improving the overall service to its customers. The final data from the inspection will be presented in an innovative asset management overview to Metropolitana Milanese.


“SmartBall has been a cost-effective solution to assess the condition of a very critical pipe in our network without causing any negative impact in our daily operations.”

–Metropolitana Milanese