Analysis

Bathing waters are defined as ‘surface waters […] other than excluded pools and waters, at which the Secretary of State expects a large number of people to bathe […]’.¹

There are many more coastal locations than inland sites designated as bathing waters, but there is a growing movement to designate more river locations as such. Bathing water bodies are regulated in England under the Bathing Water Regulations,¹ with similar pieces of legislation in other UK nations, all stemming from the European Commission Bathing Water Directive.² The Directive and subsequent Regulations stipulate a number of limits and commitments relating to water quality. Bathing waters are assessed on an annual basis by regulators, using standards that focus on microbiological quality. These standards have been derived from public health guidance, and relate to the potential public health risk of gastrointestinal illness arising from swimming in natural waters.³

In England, the latest classifications (2022) showed that 72.1% of bathing waters are at ‘Excellent’ status, as defined in the Regulations, while 2.9% are at ‘Poor’ status (intermediate categories are ‘Good’ and ‘Sufficient’).⁴ The percentage of ‘Excellent’ water bodies across England is lower than the same metric across the EU, which stands at 85.6%,⁵ but it also represents an improvement compared to the results five years ago (2017) when only 65.6% of designated waterbodies in England achieved ‘Excellent’ status.⁴

Notwithstanding the above, there is a lot more to be done to ameliorate bathing water quality: to both improve more water bodies, and also go beyond the requirements of an ‘Excellent’ classification. Significant numbers of people enjoy bathing waters as an important amenity, whether this is a beach walk and paddling in the water or swimming and water sports. The rising popularity of “wild swimming”, in combination with increased awareness of pollution from sewer overflows, means that there is an enormous amount of public attention on this topic, which has become the focus of intense media scrutiny. There are also a number of campaigning and stakeholder organisations who are very active in this area and strive to make a positive difference, such as, for example, Surfers Against Sewage, the Outdoor Swimming Society and the Ilkley Clean River Group. The public now has an expectation that as many water bodies as possible – irrespective of whether they are formally designated – should be accessible and safe for swimming, from a water quality point of view. Given the increased interest in this field, it is pertinent to examine innovation and new technologies that will provide the public with as much information as possible on bathing water quality.

It is important to note that the central goal should be for as little pollution as possible to reach our watercourses at any time. But the causes of pollution in the water environment, whether this is a river, lake or the coast, are highly complex. They involve a multitude of sources, such as intermittent and continuous wastewater discharges, agriculture and farming, road and other surface water runoff and private discharges. So, in parallel to the huge ongoing efforts to decrease the amount of pollution going into our water bodies, we should be looking at technologies to keep people informed on water quality. We should also be mindful that bathing water standards focus on public health, and hence microbial water quality only, but pollution impacts on the environment arise from a range of different parameters beyond the microbial elements, including nutrients and trace chemicals.

Historically, information on bathing water quality has been provided on boards situated by the designated bathing water body, which are updated by the environmental regulators. However, this information is usually either generic, refers to the previous classification year, or is at least one week out of date, due to the time it takes to collect a sample, transfer it to the lab and for the lab to report back results. Modern technologies mean that we can now start moving towards providing more detailed and near real-time information to bathing water users. So which new innovative technologies may help us better protect public health and the environment in bathing water sites? Let’s look at two technologies, which may bring significant transformation to the sector.

Firstly, molecular biology techniques: primarily Polymerase Chain Reaction (PCR) applications. At the moment, culture-based techniques are used for bathing water quality monitoring (as prescribed by the Bathing Water Directive). These focus on two parameters which act as very useful indicators of sewage pollution or animal waste – E.coli and Intestinal Enterococci – but provide a limited window into the microbial pathogen picture in a particular location. PCR would allow for testing of a much wider range of organisms, and would therefore provide a significantly more comprehensive picture of microbiological water quality. For example, people who become unwell after swimming in open waters often present with Norovirus-type symptoms. PCR would allow us to test for such viruses, as well as for a much wider range of pathogenic bacteria, therefore providing a much clearer link between public health and bathing water use. Additionally, molecular biology techniques could explore new risks that we are becoming aware of; for example the risk of exposure to antimicrobial resistance (AMR). Research has shown that surfers are three times more likely to harbour antimicrobial-resistant E.coli in their guts,⁶ highlighting the potential for exposure to AMR through the use of bathing waters. Molecular biology techniques could check for AMR markers, providing a different and more specialised angle to bathing water quality information. Such techniques are becoming cheaper and faster all the time, meaning that a very comprehensive picture of bathing water quality could be provided in the future on a near-real-time basis to the public.

The second promising technology in this field is artificial intelligence (AI), which is gradually becoming a part of so many different aspects of our lives. A number of AI trials are ongoing in the sector, such as a pilot project in Devon⁷ that has combined datasets from local rivers, rainfall and soil with satellite images of local land use, in order to yield water pollution predictions. Wessex Water has also been developing an app for Warleigh Weir to provide information to bathing water users, based on algorithms that give half-hourly predictions of bacterial levels on the River Avon.⁸ The app is thought to be 90% accurate compared to lab samples, with the main advantage being that it provides predictions in near real-time. With all AI technology, it is worth bearing in mind that large volumes of good input data are required for it to learn from. An evaluation of the performance of machine learning approaches to predict the microbial quality of surface waters has highlighted the significance of optimising water quality motoring data that feed into machine learning.⁹ AI technology to predict bathing water quality is in its initial stages, but it provides a promising new avenue for research and development in this sector.

Technological innovation is great, but results also need to be presented in an easy-to-understand manner so that they are useful not just to the specialists, but to the wider public. The requirement for a focus on public information has been included in the European Commission Bathing Water Directive, and is becoming more and more important as environmental awareness rises and the public rightly expects accurate and accessible information. Therefore, a key element of either of the above technologies should be the clear presentation of results. In an era of data openness, bathing water quality information must be transparent and presented in a manner which is accessible and informative to a broad audience, reaching different communities and social groups. This may be in the form of apps, online maps, phone alerts, but should also continue to include physical signage.

An amalgamation of the above innovative technologies – molecular biology and AI – could provide the ideal, unique combination of a comprehensive bathing water quality picture with near-real-time public information; allowing a range of bathing water users to make informed decisions on whether to visit a specific water body on a particular day. At the same time as exploring new technologies to monitor the bathing water environment, we all need to continue working towards reducing pollution to all of our water bodies at both the individual and community level.

Let’s enjoy and appreciate our coastal and inland bathing waters, and the huge benefits they provide to our wellbeing; while also investing in innovation to better protect the environment and provide accurate and useful information on water quality to all.

References

1. Bathing Water Regulations (2013). https://www.legislation.gov.uk/uksi/2013/1675/contents/made
2. Directive 2006/7/EC of the European Parliament and of the Council of 15 February 2006 (2006). https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32006L0007
3. Note that swimming in waterways carries a number of other serious health and safety risks outside the scope of this article; this article focuses purely on microbial bathing water quality when referring to public health.
4. 2022 Statistics on English coastal and inland bathing waters: A summary of compliance with the 2013 bathing water regulations (2022). https://www.gov.uk/government/statistics/bathing-water-quality-statistics/2022-statistics-on-english-coastal-and-inland-bathing-waters-a-summary-of-compliance-with-the-2013-bathing-water-regulations–2
5. State of bathing waters in 2022 (2022). https://www.eea.europa.eu/data-and-maps/explore-interactive-maps/state-of-bathing-waters-in-2022
6. Surfers three times more likely to have antibiotic-resistant bacteria in guts (2018). https://www.eurekalert.org/news-releases/905616; Human recreational exposure to antibiotic resistant bacteria in coastal bathing waters (2015). https://pubmed.ncbi.nlm.nih.gov/25832996/
7. AI to stop water pollution before it happens (2023). https://www.bbc.co.uk/news/science-environment-65913940
8. AI technology used for Warleigh Weir bathing water study (2023). https://www.wessexwater.co.uk/news/ai-technology-used-for-warleigh-weir-bathing-water-study
9. Evaluating the Performance of Machine Learning Approaches to Predict the Microbial Quality of Surface Waters and to Optimize the Sampling Effort (2021). https://doi.org/10.3390/w13182457