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Accurate models are critical for the effective management of leaks in our water distribution systems. The increased use of plastic pipes has emphasised the need to assess the ability of current leakage assessment tools in quantifying the real losses from complex time and pressure dependent leaks. The numerical study presented in this paper shows that traditional Minimum Night Flow (MNF) analyses provide good approximations of the leak response, when the loading history and discrete pressure regimes are accounted for, of leaks in viscoelastic pipe. The time and dependent nature of such leaks are of greater significance when the response to short time period pressure transients are quantified, important for active leakage control methodologies in particular.

It has been hypothesised that negative transient pressures may result in ingress of contaminated groundwater through leakage orifices. This paper presents results of contaminant ingress tests from a novel laboratory facility at the University of Sheffield. An engineered leak surrounded by porous media was subjected to a pressure transient resulting from the rapid closure of an upstream valve. It has been shown that a pollutant originating externally was drawn in and transported to the end of the pipe loop. Thus this paper presents the first fully representative results of contaminant ingress.

The use of plastic pipes within water distribution systems is viewed as a highly effective means to reduce our unsustainable levels of leakage. However, attention is required to understand the complex behaviour of leaks that do occur in this viscoelastic pipeline material. Results from a novel experimental investigation into the dynamic leakage behaviour of longitudinal slits in MDPE pipe are presented in this paper, reporting on the relationship between pressure head, leak flow-rate, leak area and material strain. The results show the significant time dependent leak behaviour, also highlighting the correlation between measured strain and area.