Engineering interventions that could reduce exposure of open-water swimmers to human faecal matter

Image credit: Martin Charles Hatch /

Wastewater treatment must be improved to reduce exposure to human faecal pathogens in treated effluent, according to a new report published on 21 May by the National Engineering Policy Centre.

Led by the Royal Academy of Engineering, the report’s findings are based on risk-based assessments and consultations with more than 100 engineers, wastewater experts, the water industry, campaign organisations and policymakers. This is the first time a comprehensive report has been undertaken to assess actions to mitigate public health risks associated with the use of public waters, contaminated by faecal matter from human waste.

Despite wastewater treatment works reducing the concentration of human faecal organisms, the continuous discharge of treated effluent into rivers, seas and lakes remains a source of high levels of these organisms. The report notes the rise in recreational activities in coastal and inland open waters across the UK, leading to greater public exposure to pollutants. Increased public awareness and data availability on water quality have spurred renewed scrutiny over UK water standards and necessitated a revaluation of the public acceptability of the risk.

The report acknowledges that there is a lack of evidence to demonstrate a direct, causal link between specific wastewater discharges and specific health incidents but emphasises the known public health risk from exposure to high concentrations of faecal organisms.

It focuses on the role of wastewater infrastructure in introducing primarily human faecal organisms into open water through storm overflows and treated effluent discharge. However, it does not look at agricultural runoff from livestock, wild animals, or septic tanks.

The working group examined a range of actions across storm water management, wastewater treatment, monitoring and communication with the public, and maintenance and operations. The actions proposed aim to either engineer a reduction in the hazard itself or minimise public exposure to it and the report emphasises that the choice of action will depend on local conditions, including scale, geography, policy priorities and affordability.

The report calls for collective action by industry, government, and public bodies to bolster a robust and efficient wastewater system and recommends the following actions:

Immediate actions recommended by the report:

  • Asset maintenance: Water service providers must prioritise asset maintenance, with regulatory frameworks enforcing resilience.
  • Environmental monitoring: National and devolved governments should hasten environmental monitoring rollouts, with regulators overseeing microbiological quality to inform pollution forecasts and public advisories.
  • Bathing water review: A governmental review of bathing water regulations is necessary to ensure that protections are proportionate to the public health risk.
  • Overflow management: Storage tanks can collect storm water to prevent untreated wastewater spilling into waterways, however, these are an unsustainable short-term fix, and should only be used where environmental and public health risks are greatest.
  • Runoff reduction: Authorities must explore ways to decrease urban runoff, including incentives for removing impermeable surfaces, like patios or paved over gardens.
  • Collaborative modelling: Water companies should collaborate with researchers to model catchments for improved infrastructure management.
  • Public engagement: Health and environmental authorities need to educate the public about the public health risks and work together to and improve the effectiveness of signage at designated bathing sites.
  • Disinfection assessment: The need for disinfection processes at critical sites should be evaluated as part of a public health risk-based approach.

Long-term transformational opportunities:

  • Visionary strategy: A government-led vision for the wastewater system should be established, incorporating diverse perspectives and setting measurable targets.
  • Sustainable drainage: A national strategy for sustainable drainage systems is essential to manage rainwater, reduce sewer inputs, and adapt to climate change.
  • Water efficiency strategy: The government is urged to reevaluate its water efficiency and blockage prevention strategy, potentially including a ban on non-flushable items, complemented by public engagement to foster responsible use of the water system.
  • Innovative treatment funding: Water service providers and regulators should allocate more funds for large-scale demonstrator programs to pioneer new treatment methods, enhancing performance, pollutant removal, and real-time faecal pathogen monitoring.

Enabling actions for future readiness:

  • Research investment: UKRI and other funders are called upon to fund multidisciplinary research into faecal microbial behaviour and the development of advanced monitoring technologies for real-time detection in recreational waters.
  • Skill development: There is a need to expand regulatory and engineering expertise to implement these actions and manage water quality monitoring and enforcement.
  • Wastewater champion: The appointment of a dedicated wastewater champion is recommended to facilitate cross-stakeholder collaboration and information exchange, vital for enhancing the UK’s wastewater infrastructure.

Professor David Butler FREng, Chair of the National Engineering Policy Centre working group on wastewater, says:

“Our vision for the UK’s future wastewater system is one that ensures the right balance of human health, environmental protection, and economic sustainability. But first we need a strong evidence base to understand and measure public health risks accurately. Such a foundation is essential to inform regulations, standards, and policies, enabling a united effort by governments, regulators, and water companies to mitigate health risks and ensure the safety of open waters for everyone.

Growing urbanisation and forecasts for more frequent and intense rainfall events due to climate change will mean increasing pressure is put on our ageing wastewater system. Policymakers and industry should carefully consider the actions we have outlined here and their implications in future wastewater infrastructure projects.”

Professor Chris Whitty KCB, FRS, Chief Medical Officer for England, says:

“Public waterways are a great resource enjoyed by many children and adults and can have a significant positive impact on our health. Minimising human faecal organisms in fresh water is a public health priority as well as an environmental one. Whilst there will always be challenges with the efficient management of sewers and sewage treatment works, this report provides clear technical options for how this can realistically be achieved.”

Barbara Evans, Professor of Public Health Engineering at the University of Leeds, says:

“Investments in sanitation require national vision and leadership; 150 years ago, the UK committed to eliminating cholera and made the necessary huge investments in our wastewater system; we have reaped the benefit of that vision for our whole lives, and we probably haven’t been sufficiently aware of it.  That investment is reaching the end of its life, and we owe it to our children and our grandchildren to make a new commitment and create a vision of a new wastewater system fit for the future.”