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Details of Grant 

EPSRC Reference: EP/S025642/1
Title: CBET-EPSRC: Characterizing the effects of supply hours and pressure of intermittent piped water supplies on water quality
Principal Investigator: Speight, Dr V
Other Investigators:
Douterelo Soler, Dr I
Researcher Co-Investigators:
Project Partners:
University of Massachusetts Amherst
Department: Civil and Structural Engineering
Organisation: University of Sheffield
Scheme: Standard Research - NR1
Starts: 01 January 2019 Ends: 31 December 2021 Value (£): 83,142
EPSRC Research Topic Classifications:
Water Engineering
EPSRC Industrial Sector Classifications:
Related Grants:
Panel History:  
Summary on Grant Application Form
This project will study the effect that regular loss of pressure in water distribution systems has on water quality through a collaboration between the University of Massachusetts Amherst in the US and the University of Sheffield in the UK. The research will produce a better understanding of the effect of intermittently operated piped water systems on water quality and the results can be used to develop strategies to reduce the spread of waterborne diseases.

The influence of momentary loss of pressure due to pressure transients in continuous distribution systems has been relatively well-studied. However, while there is evidence of contamination in intermittent systems and corresponding adverse health impacts, there have been few studies exploring the mechanisms affecting water quality in chronically intermittent systems. The practice of intermittent water supply (IWS) can exacerbate risks to water quality that are observed in continuous supplies by introducing atypical hydraulic conditions imposed by the four phases of an IWS supply cycle. First, when the supply is off in the distribution network, pipes are at low or atmospheric pressure and may be partially or fully empty, thereby permitting entry of contaminants through leaks from adjacent groundwater or sewage depending on the conditions. Second, the water supply is then turned on to the pipes, filling the pipes with water and possibly mobilising contaminants accumulated at the pipe wall. Third, the pipes provide pressurized supply for a limited period of time, thereby transporting the mobilised material. Finally, supply is turned off again, leaving water in pipes to drain through household connections and leaks. While these hydraulic conditions can affect many aspects of the biological, chemical, and physical quality of the water, one of the most significant health concerns is the potential for intermittency to introduce waterborne pathogens into these distribution systems and to influence their transport, survival, and growth.

Our previous work hypothesized that the main mechanisms affecting this microbiological water quality in an intermittent water supply are: 1) mobilisation of contaminants from the pipe wall interface and corresponding interactions with the bulk supply (specifically biofilms, loose deposits, and microbial growth); and 2) ingress of contamination from outside the pipe when pressure is low, through either intrusion or backflow. However, while results from our field studies of intermittently supplied networks at scale suggest these two mechanisms are important contributors to contamination as demonstrated by the presence of fecal-indicator bacteria, the relative importance of these two mechanisms has not been studied under controlled conditions. Gaining a more fundamental understanding of how interruptions of supply affect the microbiology of pipes will allow for development of strategies to control potential health risks in both chronically intermittent networks and during interruptions to otherwise continuous supplies, such as after main breaks and for seasonal water systems.

The research will use the internationally-unique 600m long temperature-controlled, real-scale pipe loop facility at the University of Sheffield alongside pilot scale test rigs to be constructed at the University of Massachusetts. The three hydraulically isolated loops in the Sheffield facility will be operated with different supply regimes (continuous supply, 12 hours of supply every day, and 12 hours of supply twice per week) to establish baseline quality parameters, determine the presence, composition, and function of microbial communities, study the biofilm structure and composition, and investigate the survival and growth of indicators of pathogens. The data generated from these experiments will be used to develop a quantitative microbial risk assessment model to evaluate the impact of varying hours of supply on the potential risk of waterborne disease.
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Further Information:  
Organisation Website: http://www.shef.ac.uk