Tolerable Gastrointestinal Illness Risks for Outdoor Water Recreationalists

Why is the research needed?

Swimming and taking part in other activities in rivers and lakes can expose people to germs from wastewater and other sources of pollution. These germs can cause illnesses such as vomiting and diarrhoea. Research has shown that the risk of illness increases as water pollution increases, but there is still uncertainty about how much risk people face when using inland waters for recreation and whether current bathing water quality standards provide enough protection.

An important part of answering these questions is understanding what level of illness risk the public considers tolerable. There is currently limited evidence about this, and people's views may differ. This research is needed to identify the levels of risk people are willing to tolerate, so these can be compared with estimates of illness risk in recreational waters.

What are we doing?

We will carry out an online survey to find out what level of risk of gastrointestinal illness (vomiting or diarrhoea) people consider tolerable when taking part in recreational activities in the sea, rivers or lakes. We will focus on illness that is bad enough to make someone miss at least one day of work or school, or stop them doing their usual daily activities.

Participants will be asked whether they consider different levels of illness risk tolerable, ranging from 1 in 380 people (0.26%) to 1 in 20 people (5%). Risks will be presented using both numbers and percentages, such as "1 in 200 people (0.5%)". The risks shown will depend on participants' earlier answers, helping us identify when they consider the risk too high. We will analyse the responses to identify the levels of risk most commonly considered intolerable and how much these views vary between people. The findings will contribute to a wider project investigating illness risks associated with recreational use of inland waters.

How are we working with communities, services and organisations?

We have involved members of the public with an interest in outdoor swimming and other recreational water activities in the development of the survey. Their feedback has helped us consider how best to explain illness risks and present questions in ways that are clear and understandable. This is particularly important because the survey asks people to consider numerical information about risks and make judgements about what they would be willing to tolerate.

The study is being carried out as part of a wider research programme led by Professor Hunter through the NIHR Health Protection Research Unit in Gastrointestinal Infections, commissioned by the Department of Health and Social Care (DHSC). The survey findings will contribute to this programme alongside research estimating the risks of illness associated with recreational use of inland waters.

What will the impact and benefits of this research be?

Through this research, we will provide evidence about the levels of gastrointestinal illness risk that members of the public consider tolerable when taking part in recreational water activities. There is currently limited evidence on this, and the findings will help improve our understanding of public attitudes towards health risks associated with recreational water use.

The findings will contribute to a wider research programme examining illness risks associated with recreational use of inland waters. They may be used alongside estimates of illness risk to help assess how these compare with levels considered tolerable by the public. In this way, the study may contribute to the evidence available for future consideration of bathing water quality standards.

What do we have planned for knowledge mobilisation and implementation?

The findings from this study will be shared with the wider research team and contribute to the overall findings of the DHSC-commissioned research programme. The results will be considered alongside estimates of gastrointestinal illness risk associated with recreational use of inland waters, helping the research team assess how these risks compare with levels considered tolerable by the public.

The wider programme will report its findings to the study commissioners, providing evidence that may be relevant to future assessments of bathing water quality standards. Opportunities to share the survey findings more widely, including through academic publications and communication with relevant organisations and recreational water users, will also be considered.

Related papers, outputs and resources

Outputs will be added once available