New Technology to Find Water Leaks in Supply Pipes

Scientists at the Fraunhofer Institute for Silicon Technology ISIT in Itzehoe, Germany, under the lead of Dr. Peter Lange, and in corporation with Italian researchers at Sensordynamics, have developed a new sensor to find holes in water supply lines. Almost half of the water send through those lines doesn't make it to the end consumer. Therefore, it is important to find and fix the leaks in the pipes. Yet, traditional sensors are too expensive for extensive use on an entire network of supply pipes. The new sensor provides a low cost and very efficient alternative. The system is currently tested in Pisa, Italy.

We take it for granted. We open the faucet and the water will flow. We rarely think about how it got to the faucet in the first place. Most of us only know that there is an intricate system of pipes somewhere in the ground that is designed to deliver the water to the faucet. Only a few of us know how it works, and even less know how much water was originally send through the pipe system, and how much did eventually really end up at our house. Yet new statistics show, only about 60 percent of the water makes it all the way. The rest gets lost through leaks in the pipe system and simply seeps into the ground. Thus, for the end consumer to fill a bucket with water, about a bucket and a half of water has to be sent through the system.

The reason for the leaks in the system is the age of the pipes, some of them over a hundred years old. The corresponding corrosion and wear and tear leads to the multitude of leaks. These leaks have to be found and fixed. However, traditional high-end flow sensors are expensive; too expensive to use on the aging system of an entire supply network.

The new sensor is in comparison cost-efficient. It is silicon-based and costs only about 5% of price for traditional sensors. The sensor is similar to that of mass air flow sensors. Such sensors are used to measure air intake in car engines. The new sensor is the first to use this principle in liquids.

The sensor consists basically of two heating wires. They are arranged on a thin membrane, one wire behind the other. The wires are heated to a constant temperature by an electric current, which flows through them. If cold water passes by the sensor, the front wire emits more heat into the water than the back wire. This is due to the fact that more of the electric current has to flow to the front wire in order to keep a constant temperature. The variance in the electrical current can be used to indicate the speed and volume of the water flowing in the pipes.

Furthermore, the sensor functions in pulse mode. This means the wires are only heated for three seconds per minute. Therefore, measurement distortions like lime deposits and air bubbles are reduced, as the wires stay mostly cold. Additionally, energy is saved and thereby the life of the sensor's battery prolonged.

According to the scientists, the first test was a success. The sensors were under water for three months, but did not show any damage. The researchers have already started the next test phase a couple of weeks ago by placing seventy prototype sensors into the water supply line network of the city of Pisa. These sensors will be in the system for several months while it operates in full mode. They will measure water flow and volume, which will indicate how much water is lost and where. The scientists collect the data via mobile phone or radio.

The scientists expect these sensors to quickly reach mass production once the tests have shown to be successful.