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Rapid urban, economic, and population growth has led to increased water demand and reduced availability. At the same time, the condition of water distribution systems has deteriorated, and water leakage has increased. Although previous research has developed models to simulate leaks in water distribution systems, these models do not consider the distribution of varying leak types and their distribution in different pipe materials, and little is known about this topic. Therefore, this study aimed to identify the most effective pipe failure distribution for analyzing failure types in various pipe materials by using the maximum likelihood approach. The study used data on water pipe failures gathered from Auckland's water network over six years (2017–2022) to accomplish its goal. The results show that the log-normal distribution is the best distribution for longitudinal, circumferential, and round holes, whereas the normal distribution is the best for blowout holes. Finally, the reported plus unreported failures were derived from the fitted distribution for estimated data. The study's findings provide valuable insights into the distribution of leak types and their occurrence in different pipe materials, which can help in developing effective leak management strategies. The discussion of the study highlights the limitations and implications of the research and suggests directions for future research to improve the accuracy of the models used to simulate leaks in water distribution systems. Overall, this study contributes to the understanding of the complex issue of water leakage and provides important information for water authorities and policymakers to develop effective strategies to minimize water loss and ensure a sustainable water supply. Practical Applications: This study offers initial insights into the type and dimensions of pipe failures occurring in different pipe materials based on photographic records of pipe repairs conducted in Auckland's water distribution system in New Zealand. An extensive literature review of pipe failure studies revealed no previous work describing the dimensions of leaks discovered in water distribution systems. This information is critical for better understanding pipe failure types and mechanisms and the development of more realistic stochastic leakage models for water distribution systems. Such stochastic models will allow the impact of leaks on system flow rates and pressures to be investigated and provide more realistic scenarios for network simulation and evaluation of leak detection algorithms. The research only had access to a limited number of failures, and it recommends more research on the types and dimensions of leaks in water distribution systems. A better understanding of pipe failure patterns will assist water utility managers and engineers in making more informed decisions on material selection, maintenance, and repair strategies, ultimately reducing water loss and costs associated with pipe failures. [ABSTRACT FROM AUTHOR]

It has been well established that leakage from pipes is more sensitive to changes in pressure than the square root relationship predicted by the orifice equation. The main reason for this is that leak areas are not static, but vary with changes in system pressure. While previous studies have shown that the leak area is a linear function of pressure for elastic materials, the effect of the viscoelastic behavior of plastic pipes on the pressure-leakage response is not yet well understood. In this study, finite element analysis was used to investigate the effect of viscoelastic behavior on round holes and longitudinal cracks in both high density polyethylene (HDPE) and polyvinylchloride (PVC) pipes. The standard differential equation for linear viscoelastic deformation was then calibrated to the finite element results, resulting in equations that accurately describe the viscoelastic variation in leak areas as functions of time. The results also showed that the time-dependent behaviors of both pipe materials are proportional to their elastic behavior, and stabilize after about 12 h. The total deformations of HDPE and PVC pipes were found to be approximately 220 and 122% of their respective elastic deformations. [ABSTRACT FROM AUTHOR]

Pressure management has been used for more than 3 decades to reduce leakage from water distribution systems. While few of these studies have been published, information on the ranges of field study leakage exponents is available. In contrast, several studies on the pressure-leakage relationship of individual leaks have been published, and verified models have been developed for predicting the response of elastically deforming leaks. The main aim of this paper was to determine whether researchers' current understanding of the pressure-leakage response of individual leaks can be reconciled with the observed pressure-leakage response of district metered areas containing many leaks. To investigate this, a model of the distribution of individual leaks and their parameters was developed based on available literature and expert advice. A repeatability study showed that such a model can indeed produce typical distributions of leakage exponents found in field studies. A sensitivity analysis of the various parameters showed that the average system pressure and condition of the system had the greatest influence on the system leakage exponent. Finally, it was shown that a small fraction of leaks with high leakage numbers (i.e., in highly flexible material or closing under zero pressure conditions) can explain the high background leakage exponents often found in systems with only background leakage. [ABSTRACT FROM AUTHOR]

Pressure is one of factors influencing leakage in water networks [1,2] . In this study, the FAVAD concept and leakage number were analysed for a number of real water network pressure management zones in the KwaDabeka Township in KwaZulu-Natal, South Africa Pressure-leakage parameters were determined for each pressure management zone. Results show that the FAVAD equation and leakage number provides useful insights into the behaviour of real networks. The analysis identified certain anomalies in the parameters of some networks, especially those with N1 values greater than 1.5. A number of potential reasons for the observed anomalies are provided. [ABSTRACT FROM AUTHOR]

This study investigated on-site leakage on 182 properties with relatively new municipal water meters in well-established suburbs of Johannesburg. A methodology was developed to estimate the on-site leakage rate from readings taken from these municipal water meters, which was then adjusted to account for metering errors. The results were analysed in 2 categories: 'Residential' properties, which consisted of single houses on individual stands, and 'Other' properties, which consisted of non-residential users and blocks of flats. A high incidence, 64%, of measurable on-site leakage was found. The average on-site leakage rates on 'Residential' and 'Other' properties were found to be 12 and 29 kl/month per property, respectively. In both cases, this represented 25% of measured consumption. Apparent losses due to on-site leakage were determined to be 10% of the on-site leakage, or 3% of total consumption. [ABSTRACT FROM AUTHOR]

High quality plumbing components are essential to ensure the efficient and safe supply of water, and minimise water losses in buildings. South African legislation requires that all plumbing components installed comply with certain standards set by the South African Bureau of Standards (SABS). Water Services Authorities are responsible for enforcing this legislation, and are allowed to set their own additional requirements for plumbing components. This study investigated the extent of non-compliant plumbing components used in South Africa through a number of methods, and concludes that compliance is roughly 50%. This points to a large problem and has dire consequences for the future of effective water use and water leakage in South Africa. A worrying finding is that the level of non-compliance seems to be particularly large in low-cost housing developments. The main reasons for the low levels of compliance are a lack of enforcement at local government level and the fact that legislation does not prohibit the import and sale of non-compliant components. The paper makes a number of recommendations for improving the situation. [ABSTRACT FROM AUTHOR]

The results of pressure management field studies have shown that the leakage exponent is often considerably higher than the theoretical orifice value of 0.5. The purpose of this paper is to identify and analyse factors that may be responsible for the higher leakage exponents. Four factors are considered: leak hydraulics, pipe material behaviour, soil hydraulics and water demand. It is concluded that a significant proportion of background leakage can consist of transitional flow, and thus have a leakage coefficient value above 0.5 (although not above 1). An important factor is pipe material behaviour: laboratory test results are presented to show that pipe material behaviour can explain the range of leakage exponents observed in the field. The complexity of the interaction between a leaking pipe and its surrounding soil is discussed and it is concluded that the relationship between pressure and leakage is unlikely to be linear. Finally, it is noted that if water demands are present in minimum night flows, the resulting leakage exponent is probably underestimating the true value. [ABSTRACT FROM AUTHOR]

This paper reports on an experimental study that was conducted to measure the leakage exponents of different types of leak openings (holes, corrosion holes, and longitudinal and circumferential cracks) and pipe materials (asbestos cement, mild steel and uPVC). A number of failed pipes taken from the Johannesburg water distribution system were tested, as well as a number of pipes with artificially induced leaks. The results of the study confirmed that leakage exponents can be significantly higher than the theoretical value of 0. 5. While leakage exponents for round holes were close to 0. 5, the values for corrosion holes varied between 0. 67 and 2. 30, for longitudinal cracks between 0. 79 and 1. 85, and for circumferential cracks between 0. 41 and 0. 52. Conclusions include that the highest leakage exponents were found in corroded steel pipes and that under certain circumstances, leakage exponents can be less than 0. 5. [ABSTRACT FROM AUTHOR]