Periodic Reporting for period 1 - Wat-Qual (Water Quality in Drinking Water Distribution Systems.)
Reporting period: 2018-01-01 to 2019-12-31
Within the EU, water is extracted from surface and groundwater sources and treated to comply with EU drinking water standards under the Water Framework Directive and Drinking Water Directive. The water is then circulated through the drinking water distribution system (DWDS) to end users, during which time its quality may deteriorate. The rate and extent of DWDS water quality degradation is influenced by: background water chemistry and treatment including presence of a disinfectant residual like chlorine; the design of the network; the age and configuration of the pipe infrastructure; the hydraulic conditions of operation including customer demand patterns; maintenance activities like flushing; and procedures for repairs.
While all water utilities must comply with EU Water Framework Directive and Drinking Water Directive requirements for specified water contaminants, many features of operation are not dictated by these regulations such as choice of treatment processes, procedures for maintenance activities, and hydraulic operations of the DWDS. Each water utility has its own sets of national standards and utility-specific procedures, many of them traditionally passed on and not always based on scientific evidence. Some of these typical practices, like flushing, may improve water quality in certain cases but the potential also exists that these activities can impair drinking water quality, resulting in regulatory violations and even waterborne disease.
Across the water industry, it is not clear what practices are most successful at ensuring clean drinking water under different conditions. Furthermore, localised issues concerning infrastructure design, historic protocols and national regulation make it challenging to identify and implement best practices.
This project bridged the gap between science and practice, involving water utilities and researchers from multiple locations across Europe along with third-country expertise, to examine DWDS operational practices and use scientific research approaches to better understand the water quality impact of different interventions. The outcome will be improved knowledge and identification of best practices, with dissemination to a wide range of countries and water utilities, to ensure that Europe’s drinking water remains of the highest quality in the world.
The primary research aim of Wat-Qual was to understand the impacts of DWDS flushing, chlorination, and maintenance/repair on drinking water quality across the diversity of practice in Europe, bringing together scientific and practical approaches to identify and disseminate best practice guidance and tools.
While all water utilities must comply with EU Water Framework Directive and Drinking Water Directive requirements for specified water contaminants, many features of operation are not dictated by these regulations such as choice of treatment processes, procedures for maintenance activities, and hydraulic operations of the DWDS. Each water utility has its own sets of national standards and utility-specific procedures, many of them traditionally passed on and not always based on scientific evidence. Some of these typical practices, like flushing, may improve water quality in certain cases but the potential also exists that these activities can impair drinking water quality, resulting in regulatory violations and even waterborne disease.
Across the water industry, it is not clear what practices are most successful at ensuring clean drinking water under different conditions. Furthermore, localised issues concerning infrastructure design, historic protocols and national regulation make it challenging to identify and implement best practices.
This project bridged the gap between science and practice, involving water utilities and researchers from multiple locations across Europe along with third-country expertise, to examine DWDS operational practices and use scientific research approaches to better understand the water quality impact of different interventions. The outcome will be improved knowledge and identification of best practices, with dissemination to a wide range of countries and water utilities, to ensure that Europe’s drinking water remains of the highest quality in the world.
The primary research aim of Wat-Qual was to understand the impacts of DWDS flushing, chlorination, and maintenance/repair on drinking water quality across the diversity of practice in Europe, bringing together scientific and practical approaches to identify and disseminate best practice guidance and tools.
Overall, 41.8 secondment months took place in this project, spanning 15 partners across 10 countries. In addition to the experience gained from visiting another country and exchanging knowledge of drinking water quality, more than 20 conference presentations, 10 published papers, plus a special issue of the journal Water on drinking water distribution system (DWDS) water quality resulted from this project.
A number of project outcomes advanced modelling tools for flushing and material mobilisation, including Aquarellus (KWR) and 3DNet (University of Belgrade). The results from the laboratory investigations have shown there are distinct differences in sediments from different networks. The Dutch sediments appear to be lighter and less tightly bonded while the UK sediments are heavier and more difficult to mobilise. Research to characterise the settling velocities for these different sediments has resulted in development of a method to quickly establish and compare settling velocities from different samples. This difference in sediment type may explain the differences in how discolouration is perceived and modelled in the Netherlands and the UK, where opinions have typically differed about the key processes governing discolouration.
In terms of disinfection in DWDS, the research explored hydraulic factors which are driven by customer demands. Investigation of smart meter data revealed that there is great potential for this approach, although current datasets from smart meters have individual features that make them difficult to combine. Source water quality has also been evaluated in terms of corrosion byproducts and organic carbon, and that sediments which accumulate in storage facilities in the DWDS can exert chlorine demand, thereby lowering the chlorine available for disinfection. Disinfection using alternatives to chlorine has been found to be a potentially useful alternative in the future thanks to the availability of low-power UV disinfecting LEDs. Temperature dynamics have also been investigated, with measures to address temperature increases in DWDS explored and the impacts of temperature on biofilm microorganism presence revealing that climate change could have a significant impact on water quality in DWDS through temperature alone. Options for maintaining chlorine residual could include the implementation of low ‘trickle’ flows from hydrants at distant ends of the DWDS.
A key element of pipe repair is the ability to shut down areas of the network quickly when a problem is detected. The implementation of network sectorisation, where a DWDS is divided into sections, is one way to improve shut down times for repair. Tools for better understanding the DWDS resilience and optimising sectorisation were developed during several secondments. Real-time response tools for addressing DWDS problems were also expanded. Repair techniques were compared between Czech Republic and Spain, noting differences in procedures to pressure test and return pipes to service to determine best practices.
A guidance manual containing a series of fact sheets suitable for use by water utility staff has been developed as an outcome of this project and is available to download via the project open data project site: https://figshare.shef.ac.uk/projects/Wat-Qual_Water_Quality_in_Drinking_Water_Distribution_Systems/74781. Datasets, videos, and other information can also be found on this site.
A number of project outcomes advanced modelling tools for flushing and material mobilisation, including Aquarellus (KWR) and 3DNet (University of Belgrade). The results from the laboratory investigations have shown there are distinct differences in sediments from different networks. The Dutch sediments appear to be lighter and less tightly bonded while the UK sediments are heavier and more difficult to mobilise. Research to characterise the settling velocities for these different sediments has resulted in development of a method to quickly establish and compare settling velocities from different samples. This difference in sediment type may explain the differences in how discolouration is perceived and modelled in the Netherlands and the UK, where opinions have typically differed about the key processes governing discolouration.
In terms of disinfection in DWDS, the research explored hydraulic factors which are driven by customer demands. Investigation of smart meter data revealed that there is great potential for this approach, although current datasets from smart meters have individual features that make them difficult to combine. Source water quality has also been evaluated in terms of corrosion byproducts and organic carbon, and that sediments which accumulate in storage facilities in the DWDS can exert chlorine demand, thereby lowering the chlorine available for disinfection. Disinfection using alternatives to chlorine has been found to be a potentially useful alternative in the future thanks to the availability of low-power UV disinfecting LEDs. Temperature dynamics have also been investigated, with measures to address temperature increases in DWDS explored and the impacts of temperature on biofilm microorganism presence revealing that climate change could have a significant impact on water quality in DWDS through temperature alone. Options for maintaining chlorine residual could include the implementation of low ‘trickle’ flows from hydrants at distant ends of the DWDS.
A key element of pipe repair is the ability to shut down areas of the network quickly when a problem is detected. The implementation of network sectorisation, where a DWDS is divided into sections, is one way to improve shut down times for repair. Tools for better understanding the DWDS resilience and optimising sectorisation were developed during several secondments. Real-time response tools for addressing DWDS problems were also expanded. Repair techniques were compared between Czech Republic and Spain, noting differences in procedures to pressure test and return pipes to service to determine best practices.
A guidance manual containing a series of fact sheets suitable for use by water utility staff has been developed as an outcome of this project and is available to download via the project open data project site: https://figshare.shef.ac.uk/projects/Wat-Qual_Water_Quality_in_Drinking_Water_Distribution_Systems/74781. Datasets, videos, and other information can also be found on this site.
This project has advanced understanding of drinking water quality dynamics in water distribution systems across a number of countries, with significant benefits from sharing of experience that will be seen beyond the project lifetime. As reported by all participants without exception, they each experienced tangible and intangible benefits from participation in the project across all career stages. For ESRs, the opportunity to access real-world data sets for analysis greatly improved the quality of their PhD research and resulting publications. A number of participants, both ESR and ER, learned new laboratory and analytical skills which will further their advancement in their home institution. The consortium participants have had a number of career successes, including new employment opportunities and promotions. The dissemination of results at conferences and workshops with water utilities from this project also provided valuable training opportunities for ESRs to grow their presentation skills to different audiences.
A number of new collaborations have also resulted from this project, as can be seen in the number of publications already produced by the consortium that include authors who would not otherwise have worked together. The full consortium agreed at its final workshop to seek further opportunities to work together in the future.
A number of new collaborations have also resulted from this project, as can be seen in the number of publications already produced by the consortium that include authors who would not otherwise have worked together. The full consortium agreed at its final workshop to seek further opportunities to work together in the future.