Over the last 12 months a 140 strong team from United Utilities have saved water the equivalent of 360 Olympic sized swimming pools - using wooden 'listening sticks'.
Many of the most wasteful leaks are underground and hidden from view, requiring the team to rely on good hearing, old fashioned know how and latest digital technology to find them.
Many leaks are detected late at night, when reduced traffic noise makes it easier to hear the sound of escaping water.
Hannah Wardle, United Utilities leakage manager said: "These leaks are often hidden under the streets, with no visual signs that water is being wasted. We encourage our customers to save water around the home, as it makes good economic and environmental sense. Our nightly battle against hidden leaks is a way of keeping our own house in order."