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Water utilities commonly use acoustic equipment to locate leaks. Although acoustic equipment is generally considered satisfactory for metallic pipes, its application to plastic pipes could be problematic. This study found that leaks in plastic pipes could be located using acoustic techniques; however, there were several difficulties. Professional leak detection teams using leak noise correlators rarely succeeded in locating leaks because the frequency range selected automatically by correlators (or manually by operators) was usually too high. The frequency content of leak signals from plastic pipes was mostly below 50 Hz. Listening devices were ineffective unless they were used very close to leaks. Acoustic leak detection methods can be made more effective by revising the automatic-mode algorithms of correlators, using finely turnable noise filters, and measuring leak signals with hydrophones or highly sensitive vibration sensors. Nonacoustic methods such as radar, thermography, and tracer gases, appear promising.

The National Research Council of Canada (NRC) has recently completed a project to assist the City of Montreal in determining the condition of its water and sewer system. NRC staff members reviewed available and future diagnostic techniques for both systems, conducted experiments on corrosion monitoring, CCTV inspection and mechanical inspection methods and provided general scientific advice during the course of the project. This paper describes the results of the review of diagnostic techniques for metallic and pre-stressed concrete pipes. Both older techniques such as water audits and leak detection and new approaches such as acoustic emission monitoring and remote field effect inspection are discussed. Advantages and disadvantages of each technique are tabulated and approaches are suggested for combining the different techniques to provide a complete diagnosis of a water system., Appeared in the Seminars on Water & Sewer Infrastructure Systems: Challenges and Solutions, 2000

La corrosion par piqure de tuyauteries d'eau en cuivre est la cause de rupture des installations de plomberie domestiques

Twenty years ago the producers and distributors of oil, natural gas, propane, and other more exotic commercial products were only superficially concerned with loss of their product due to leakage. More attention was given to the safety hazards posed by a leaking combustible product and the possibility of fire or explosion. There was little or no regard for dollar loss of product. In fact, the amount of leaking natural gas was estimated to be sufficient to meet the needs of the entire state of Indiana.

Systeme CADD de calcul et de dessin sur ordinateur pour la ville de Des Plaines (IL) pour la verification et la detection des fuites

A review is presented of the applications of radionuclear technology in research on improvements in water supply and waste disposal practices. Among the applications are analyses, disinfection, leak detection, and flow measurement. Possible future applications are discussed briefly. (D.L.C.)

More demands are being placed on aging or inadequate water distribution systems as urban growth occurs concurrently with escalating costs. The obvious solution is increasing the efficiency of existing systems combined with logical planning for expanding the capacity of the systems in the most economic way possible. Traditional assumptions about a specific distribution system must be replaced with realistic information based on field investigations and statistical projections of probable future needs.

The drought of the 1970s that forced water conservation awakened the water industry to the benefits of leak detection. The fuel drought of the 1980s and the resultant high cost of energy has brought about a new era for management with productivity being the key word. There is an opportunity to hold the operating costs of power and chemicals in check by means of leak detection and repair. Many water utilities have unaccounted-for water of more than 30 percent. Well-managed utilities report losses of half this amount. Consultants in the field of leak detection can help control these losses. On Jun. 12, 1975, AWWA authorized a committee on leak detection "to assess the state of the art of leak detection and to promote through whatever means available the development of feasible means of leak detection." Leak detection and the associated concept of unaccounted-for water is not new to AWWA. Leak detection was addressed at AWWA's first national convention in 1881 and was discussed in articles in the first issue of JOURNAL AWWA. In this country and in Great Britain the subject has been discussed for 100 years. The consulting engineer Louis E. Howson* wrote in Journal AWWA in September 1928: "The problem of reducing the quantity of unaccountedfor water is like that of caring for the poor, with us always. Well over 100 years ago, one of our pioneer eastern water works systems, in attempting to reduce

Wendell Philips, explorer, scientist, and oil manager, once said that had the Queen of Sheba known what would befall her kingdom after her demise, she would have urged her director of public works to pay greater attention to the Yemen irrigation-water distribution system, its maintenance, and system leak detection. Perhaps because she did not have modern methods of leak detection at her disposal, she did not order improved maintenance; or perhaps the costs were exorbitant relative to other priorities: nonetheless, the indictment of history is that she or one of her successors or counselors failed to bring into perspective the cost-benefit factors of a maintenance program, and a rich kingdom was ultimately forfeited when its water system fell into disrepair. It is to be hoped that archeologists sifting through the antiquities of the future in the areas for which water utility managers are responsible will find a better record. But the potential for neglect is always there. In probably no area of human endeavor is the adage "out of sight, out of mind" more applicable than to the subject of leaks in water mains buried several feet below the surface of the ground. For this reason, it is important to discuss some of the modern techniques for locating leaks, and the reasons why the benefits are well worth the costs of starting or accelerating a leak detection program. Frontinus, in Roman times, used about the same method that most water utilities use to locate leaks

Tig. 2. Economic Repair Point as a Function of Water Cost THE losses MATTER has received of a great water-system deal of losse has received a gr at deal of attention especially during the Northeast drought of 1961-66. Then, the paucity of water made some people aware that losses from major city systems, such as New York City's, were quite large and could constitute a major potential source of "new water." Data on the extent of municipal-system losses are difficult to find. The

THE aware Denver of the Water problems Board of has pipeline been aware of the oblems of peline corrosion for many years, but it was not until 1960 that a separate group was created to handle corrosion control design and corrosion control maintenance functions. Prior to that time, employees interested in the Board's corrosion problems were able to devote only small percentages of their time to the subject, and it became apparent that not only were pipeline corrosion leaks not being mitigated, but also that the incidence of their occurrence was actually increasing. It was for this reason that our chief engineer requested a study of the matter be undertaken, and from this study was developed what is the nucleus of our present-day corrosion control section. This section is concerned with all facets

The problem of leakage and the benefits of a leakage detection program need to be assessed in light of the economic and resource waste caused by water main leaks. It is obvious that leaks in a water system at any place between the raw water collection point and the point of final water consumption are sometimes very costly. Lack of attention to leak detection, whether by the water utility or the end user, cannot be tolerated in today's world of costly energy and limited resources. On the whole, private water companies appear to be more alert for water loss because of the profit motive and the scrutiny of public utilities commissions, but many municipally-owned water utilities also do an excellent job. The caveats expressed here are directed to the water utility which, having calculated the percentage of unaccounted-for water, does nothing to reduce this water loss.