Research in Focus: Safeguarding Water Quality for the Future

As part of #BiofilmWeek, we’re highlighting interesting and exciting biofilm research being undertaken across our NBIC partner research institutions by early career researchers, PhD students and our Interdisciplinary Research Fellows.

We interviewed Dr Katherine Fish, a post-doctoral researcher in Civil and Structural Engineering at the University of Sheffield. Katherine tells us all about her research surrounding biofilms within drinking water systems.

What is your primary area of biofilm research?

My primary area of biofilm research centres on understanding biofilm development and behaviour within our engineered drinking water systems, in particular the piped network that takes treated water to our taps – the distribution system. Biofilms form on the inner surfaces of the pipes and associated assets that form our drinking water distribution systems and can degrade water quality and infrastructure integrity.  I’m interested in understanding how different conditions within a pipeline (management conditions, water quality, pipe materials) influence the kind of biofilms that develop, how these different biofilms then interact with water quality and how we could better manage biofilms to mitigate their impacts. I am particularly interested in understanding how current and emerging microbial management approaches within water systems impact biofilms and, in turn, how biofilms respond to these practices. This understanding can then inform alternative approaches, predictive models and proactive management for our water systems, to safeguard water quality and, ultimately, public health and us as consumers.

Dr Katherine Fish Engineering

Are there any collaborators on the project?

As part of our research in Civil and Structural Engineering at the University of Sheffield, we as a group work with a lot of different people and stakeholders in the water sector, which includes a variety of UK water companies and international collaborators in industry and academia. You can read more about our various collaborative projects on the University of Sheffield website.

The NBIC sponsored projects I have been involved with have involved collaborations with Welsh Water and Akzo Nobel. I’m also working on a project at the moment with Andy Nichols and colleagues in Sheffield’s Electrical Engineering department, where we’re looking at developing electrical sensors to detect biofilms in situ, so we’re partnering with electrical SMEs on that project. Although not NBIC funded, I’m also working with the Health and Safety Executive and Sellafield Ltd, we have a PhD project looking at the rapid detection of Legionella within biofilms in cooling towers.


What industry or sector does this research relate to? (e.g., health, biofouling)

Drinking water quality is integral to our lives, so this research has impact across sectors. The biofilm research we do at Sheffield is industry facing, addressing water quality and infrastructure management, understanding the biofilm interactions within our drinking water systems to enable water providers to better manage our water resources. Ultimately, this all falls under safeguarding water quality for the future, which is about protecting public health and relevant to every single one of us. Covid-19 has certainly highlighted the importance of a reliable and safe water source, something that perhaps we had previously taken for granted.


What is the current situation within your sector?

The provision of safe drinking water quality is an accelerating global challenge. With the climate emergency, increasing urbanisation, growing populations and changes in water use, we need to make sure that we are sustainably managing water quality as well as availability. A recent published study in the USA recorded 7.45m waterborne illnesses annually (with >600,000 people hospitalised, and an economic cost of $2.39 billion), the predominant cause of which is biofilm-associated pathogens. This shows that even where we have modern engineered drinking water systems, we have biofilms, and they can cause us problems.

In the UK we have billions invested in our drinking water infrastructure. In England and Wales alone, we have over 400km of drinking water pipe, so that’s enough pipe to stretch from the surface of the Earth to the Moon, and then for it to start to come back again. This is ageing and buried, making it difficult to access. That is what we are distributing our cleaned, treated water through to consumers. It presents a vast surface area, which when you look at the estimated area, it’s greater than some of the smaller European countries. Basically, a huge area that biofilms can form on. Therefore, it is absolutely critical that we understand the interactions between these biofilms on the inner surfaces of our infrastructure, and the water we’re delivering.


What unmet need does this research address, and how will it impact on the public?

Current microbial management and microbial regulation within drinking water is focused on the planktonic (free living) microorganisms within our water, and is not considering the biofilm. But we know that the majority of microorganisms within our (buried) systems are living within the biofilm, so there is a global need for methods and protocols to be developed to be able to detect, analyse and proactively manage these biofilms and their impacts.

Part of the research that we do at Sheffield is about exactly that, looking at how we can best understand what is happening within the pipe systems and provide solutions for the water companies to use within a proactive way.


What research is taking place in this field, how is your research distinctive? Are there challenges to overcome?

There’s a lot of really exciting and good quality research going on in biofilms in general and microbiology within drinking water systems. Quite of a lot of research is focused on the microbiome, sequencing and understanding “who” is within our bulk-water and at the walls of our water systems. At Sheffield, we take a holistic approach, so we want to understand all aspects of the biofilm. In particular, the Extracellular Polymeric Substances (EPS), so this is the ‘glue’ that the microorganisms exude, this is what holds them together and sticks them to a surface, it also provides protection against chemicals, the environment and mechanical stability. Basically, you wouldn’t have a biofilm without EPS! And understanding EPS is critical to understanding and predicting biofilm mobilization and behaviour in these systems.

At Sheffield, we’re keen to ensure that the research we do is transferable to the real world, so it can be used to inform and guide management of operational systems.  That’s why having our internationally unique, full-scale drinking water distribution test system is so exciting, as we’re able to control the environment at laboratory level and perturb it in ways you can’t do with a live network, we’re able to obtain water and biofilm samples, whilst replicating the real world.

There’s been an explosion in different analytical techniques across biofilm research thanks to the efforts of research groups worldwide. These are enabling us to look at biofilms in more detailed ways, and with improved levels of limits of detection. We need to ensure this is balanced with appropriate biofilm samples. In the drinking water sector that I work in, it is quite hard to sample biofilms from operational systems as it is a live system connected to consumers. I think this is a challenge beyond distribution biofilm research though, as a wider community it is important that the samples we’re analysing are representative of our systems for research to have the most tangible impact.

One strand of our biofilm and water quality research has demonstrated the association between biofilm formation and mobilisation within distribution systems as a driver for the accumulation and subsequent mobilisation of material that causes drinking water discolouration. Discolouration is the leading cause for customer contacts with water utilities and by integrating biofilm research with engineering understanding and modelling we as a team are helping improve the way discolouration is managed. It is also important to recognise that discolouration can mask other water quality issues so by reducing discolouration you’re likely improving water quality in general.


Have there been any key moments in your research journey you can share with us?

Ooo, so many! A personal highlight for me was being awarded my first grant as PI, which was through NBIC. This collaborative industry facing project was such an achievement, and the whole experience was incredibly valuable for me as an early career researcher. 

A key moment was (and continues to be!) the novel development and application of methods to look at drinking water biofilms holistically from full-scale systems, because they do present a challenge. It’s by getting that rigour and developing those analytical techniques that we’ve then been able to ask some super exciting and real-world relevant research questions, like the chlorine residual impact on biofilms, and demonstrating that there could be unintended consequences to the ways that we’re currently trying to manage these systems. This was another key moment in my research journey, obtaining unexpected and perhaps controversial data!

Residuals of chlorine are often maintained within our drinking water. This isn’t a universal approach, there are countries that don’t use a disinfection residual. Countries that do use it, like the UK, use it because we want to protect against microbial contamination. What we don’t think about is how the residual chlorine in our water potentially impacting our biofilms, and is it having a selective pressure on them. This is precisely what our recent paper set out to explore. And we found that systems with a higher chlorine residual had distinct biofilms with greater potential to cause discolouration. This was really interesting as it’s demonstrating that we have these microbial management techniques that do work, but are they having an unintended consequence that could be a bigger problem for us in the future? Should we be doing this in a different way? We’re not saying don’t use chlorine, but we’re saying that perhaps we need to understand more about how it is functioning, so that we can be more careful with our disinfection regimes.  Being at the forefront of this research and the discussion that we need to have about this is very exciting.


How has NBIC supported your work and career as a researcher?

Having NBIC as a network of biofilm researchers is absolutely invaluable, for me that is the greatest achievement of NBIC. That connectivity of a biofilm community – research and industrial – around the world, as well as in the UK is so useful for developing your ideas and finding collaborators, and actually solving real-world problems.

Being an applied microbiologist within civil and structural engineering, NBIC definitely gives me that exposure to wider biofilm research and likeminded people doing interesting, exciting work in different areas. This then sparks ideas of how research in other areas could be relevant or applicable within your sector.

The opportunity of NBIC Proof of Concept funded projects, as an early career researcher has been so beneficial for the experience of writing proposals. Being awarded a POC project allows me to demonstrate research independence, running a project and delivering it on time and within budget, that experience is so important. These skills give you a platform to be able to launch an independent research career from, and NBIC has been so supportive in that.


Have you been involved in any public engagement or outreach related to your work?

As researchers, I think we have a responsibility to share the research that we’re doing with various audiences, not just academia and industry. For that reason, I’m really eager to take part in outreach and engagement, and I jump at any chance to challenge what an engineer is – who we are and what we do – to try and encourage diversity and inclusivity.

One of the projects I’ve been so excited to be a part of is the outreach with Dr Alison Buxton, as part of her Maker{Futures} project. This whole programme is about children leading their learning. A lot of outreach is focused at GCSE level and above, but I think it’s really important that we’re also engaging with the next generation earlier, to nurture that idea of creativity and problem solving, which is what we want going forward into research.

Working with Alison, we developed the ‘Mighty Microbes’ activity, which is all about getting across this idea that not all microorganisms are bad. Biofilms get a bad reputation as well. They’re often talked about as something that should be eradicated, which is frankly impossible, certainly in my area as you’re never going to completely remove a biofilm from a pipe. So, it’s much more about transforming that understanding of how to manage biofilms, realising that they’re not all bad, there are some good microorganisms as well. ‘Mighty Microbes’ was about exactly that, understanding the starting point of what a microorganism is, and then setting this up so the children could learn about different microorganisms and make super heroes, and super villain toys that had some of the different characteristics of those microorganisms. Being involved in this was an absolute pleasure and a joy, and I am excited to be part of more projects like this in the future.

Find out more

If you are interested in learning more about this research theme and would like to connect with Katherine, please contact NBIC at


Dr Katherine Fish, Research Associate from the University of Sheffield.

Women in Engineering: Shaping our world