Financial Benefits from Seven Years of Water Loss Control Utilizing theSahara® System at Thames Water in the United Kingdom

Thames Water Utilities Limited is the largest water and wastewater services company in the United Kingdom. It serves 13 million customers in London and across the Thames Valley, from Kent and Essex in the east to the edges of Gloucestershire in the west. The utility business treats and supplies an average of approximately 2,700 million liters (713 million US gallons) of water per day. In London as a whole, over a third of mains are more than 150 years old. Over half are more than 100 years old. Thames Water initiated trunk main leakage reduction programs concentrating on unaccounted for water losses in its transmission mains before the distribution network. A range of new and traditional leak detection methods was compared. Parameters included cost of operation, sensitivity of detection and accuracy of location. Thames concluded that the Sahara® Leak Location system was the most accurate and cost effective way of detecting and locating trunk main leaks. Consequently, Sahara was used exclusively for subsequent phases. To date, over 960 surveys have been completed and over 960 leaks have been located with Thames Water reporting that, recently, the average leak repaired is approximately 0.15Ml/day (25 US gallons/day) arising mainly from deteriorated lead run joints on cast iron mains and corrosion through the wall of steel mains. In excavating at the identified locations, Thames Water quoted a near 100% accuracy record. This paper discusses the financial benefits to Thames Water from the annual volume of leaks identified within their water transmission system in the eight years from 1998 to 2005, including the cumulative leakage found as well as the approximate leak volume per distance inspected each year.