BTO 2018 – 2023 What have we learned?

KWR researchers look back in publication on six years of collective research for the water utilities

Another six-year period of the Joint Research Programme (BTO) with the water utilities was recently concluded. KWR researchers reflect in the H2O magazine on what was learned over this period.

The Dutch drinking water utilities and a Flemish one (De Watergroep), together with KWR, form a research collaboration that is unique in the world. In the Joint Research Programme with the water utilities (‘BTO’ in its Dutch abbreviation) they work together in research related to drinking water. For more than 40 years they have committed to multi-annual contracts, which also always include the broad outlines of the research themes. The research agenda for these BTO programmes are always determined and adjusted in close consultations between KWR and the drinking water utilities.

Another six-year research period came to a close in 2023, and in 2024 a new six-year contract came into effect. This is therefore a good moment to look back on the research over the last six years. What was learned during this programme? Several KWR researchers answer this question in reference to their area of expertise.

Better approach to drought

In this latest BTO period (2018-2023) the Netherlands had for the first time to deal with the problem of drought on a large scale. For this reason, alternative sources and reuse, but also governance, became prominent items on the agenda, according to Ruud Bartholomeus (Chief Science Officer of KWR) and Henk-Jan van Alphen (Researcher, resilience management and governance). Sija Stofberg (Researcher, geohydrology) also points to the rapid development of the drought theme during the latest BTO contract: ‘the approach became more strategic and source protection and diversification now play a significant role. By taking stock of the situation at the different drinking water utilities and identifying trends, the water utilities were able to learn from each other.’

WiCE: on the path to sustainable circular

Besides the ‘traditional’, purely technical questions, the drought issue also raised socio-scientific questions. The new Water in the Circular Economy (WiCE) programme represented a more procedural innovation, which is based on but also runs parallel to the traditional BTO. The drinking water utilities, Water Authorities, companies, municipalities, provinces and the national government all work together within WiCE. In the context of the transition to a sustainable and circular design of the water system, there is a special need to work with other parties in creating a vision and tackling the new challenges.

This calls not only for technical knowledge, but also for answers to the question as to what is done with this knowledge and how this can be achieved. Kees Roest [Senior Researcher, energy and circular systems, and programme manager of the Top Sector Alliance for Knowledge and Innovation (TKI)] agrees. ‘WiCE has contributed a great deal to the sense of urgency, and to developing a strategy to tackle the problems and bring about a sustainable circular system.’

Taking better account of groundwater quality

Besides the drought, which leads to problems with the quantity of available freshwater, the deteriorating quality of the water also plays an important role. It is known that surface water is highly polluted, but groundwater quality is also deteriorating due to anthropogenic factors. One of the latest problems is that PFAS are also being detected with greater frequency in the groundwater. Special attention has been directed to this issue in the Water Quality Knowledge Impulse programme. ‘Because reactive substances like pyrite and organic material degrade in the soil as a result of nitrate leaching and drought, the system is increasingly vulnerable,’ says Gijsbert Cirkel (Senior Researcher,  hydrology/hydrochemistry). As a consequence, over the latest BTO period the question of how groundwater-related concerns (recharge of groundwater, reduction of leaching of plant protection products and fertiliser) can be better taken into account in the process of increasing the sustainability of agricultural soils.

Image 1. Research on brackish groundwater at Dunea in Scheveningen, February 2022


Research was also conducted into the possibilities of inferring substance properties, which are relevant for the transport and degradation during soil aquifer treatment, from molecular properties of organic micropollutants (OMPs) by means of QSARs (quantitative structure activity relationships). Research along a number of measuring arrays at abstraction sites shows that major challenges remain, particularly in the area of charged OMPs. This will be worked on during the upcoming BTO period. Cirkel: ‘The first steps have been taken in modelling the PFAS transport in the vadose zone, as a means of getting a better grasp of the risks that these substances present for the groundwater. We are also investigating water-quality aspects during infiltration and recharge. This research will also be continued during the next BTO period.’

Nitrogen and nature

Nitrogen deposition is also a tough challenge for the drinking water utilities, who are big nature managers. ‘This is why we have for instance researched the effectiveness of mitigating measures,’ continues Cirkel. ‘We found that the sand drift in the dunes helps, but that the sod-cutting of heaths is not a useful measure. Work was also done on improving methods and techniques for ecological impact assessment of groundwater level and seepage demands. These are incorporated in the WaterWijzer Natuur. Research on production-technical aspects involved for instance a new tool to optimise well-switching regimes, allowing water utilities to ensure that the quality of abstracted groundwater is constant, while simultaneously minimising the occurrence of well clogging.’

Image 2. Research on infiltration in a drinking water abstraction area, February 2022

Water treatment processes: process improvement through modelling and big data

The deteriorated water quality from sources and the switch to alternative sources make great demands on water treatment processes. Particularly in the case of new types of pollution, this requires lots of time and money to determine the most appropriate treatment. For this reason, according to Bas Wols (Senior Researcher, water treatment and resource recovery), the latest BTO focused a lot of attention on treatment process modelling. ‘Mathematical descriptions were already available for some treatment processes like membrane filtration, (advanced) oxidation and adsorption on activated carbon, but the input was still needed of substance-dependent parameters – and these are often unknown, especially for new substances. With the quantitative structure property relationships (QSPRs) we can now often mathematically predict these parameters.

‘It is therefore becoming increasingly possible, on the basis of the molecular structure of a substance, to predict how it will behave in a given treatment process. This research will continue in the new BTO programme. This however does not mean that modelling can entirely replace the traditional, experimental research. Thus, research has been done on improving the biological stability of water by analysing which organic material fractions are responsible for it.’

Rapid filtration and OMPs

Rapid filtration processes have been applied for decades, though they are still not yet well understood. Wols: ‘In this regard, we have done research on the possibility of producing water without colloids in a classical treatment process.  That some OMPs undergo biological degradation in treatment processes was already known from research on sand and activated-carbon filters, but it also seemed that this could play an important role in rapid filters. In addition, during the latest BTO period we also investigated whether, and if so how, we could stimulate this biodegradation.’

Big Data

The removal of PFAS has quickly grown in importance in recent years. A great deal of research is focused on the question all over the world, as well as within the BTO. Wols: ‘We are looking at the pros and cons of particular techniques, and at new developments that could potentially be implemented in (Dutch) drinking water treatment.’ Furthermore, research has been done on water-quality parameters that play a role in the leaching of asbestos-cement pipelines. In all of these processes, modelling and big data are increasingly playing a prominent role.

Water-quality analysis improved, stricter treatment requirements needed

The research into the quality of surface- and groundwater was also improved during this BTO programme. Wols: ‘The analytical methods for polar compounds have been improved, producing more valuable information on both water quality and on the effectiveness of various water treatment processes. At the same time, the better analytical methods have shown that some substances are (much) more toxic than originally thought – and this leads to new and stricter treatment requirements. The best-known example at the moment are in fact PFAS, which can be found in sources practically all over the world and are very difficult to remove with traditional treatment techniques.’

Non-target screening and bioassays strengthen knowledge of toxicity

The detection and identification of micro- and nanoplastics are also in the spotlight, particularly now that a measurement obligation for microplastics in water for human consumption is to be introduced. ‘In this context, non-target screening plays an important role: it does not search for a specific compound, but takes a close look at the entire water matrix,’ says Tessa Pronk (Researcher, chemical water quality and health). ‘In addition, bioassays are frequently used to assess the possible effect of the water quality on living organisms.

‘Machine learning and, once again, QSARs play an increasingly prominent role in the analysis of samples and the identification of unknown compounds, but also in the prediction of toxicity.’ To make it possible to prevent new pollution, more and more attention is being paid to environmental forensics research on the key factors for water quality. ‘In this way we can identify (possible) sources.’ In the water infrastructure research, the risks associated with lead in indoor installations and with brass components in water meters were also identified.

Image 3. Research into microplastics in surface water, October 2019

Faecal and opportunistic pathogens under scrutiny

The presence of (primarily the pathogenic) micro-organisms has had a big impact on water quality. The behaviour of micro-organisms in the subsurface’s vadose zone has been better clarified and research has examined which groundwater abstraction activities are vulnerable to micro-organisms. For faecal pathogens, particularly in groundwater, the mandatory risk analysis was improved in the latest BTO. Furthermore, faecal pathogens were studied more closely: opportunistic pathogens were given greater attention. Pronk: ‘At this moment, we are working on faster measurement methods for Enterococci and on the use of ATP measurements to replace colony counts.’

Image 4. KWR test lab, February 2015

Busyness in the subsurface affects temperature and regrowth in the distribution network

‘We are learning constantly more about the sources of microbial growth in the distribution network, and therefore also about how to manage it,’ says Patrick Smeets, Senior Researcher, microbiological water quality and health. ‘This increasingly involves the application of molecular methods. During the latest BTO period, besides drought and PFAS, a third theme arose: the busyness in the subsurface, where more and more pipelines are being installed. The installation of heating networks, among others, can result in high temperatures underground, which can have an impact on the biological stability – and thereby on possible bacterial growth in the pipe network.’ Antibiotic resistance, which can be demonstrated in more and more places in the drinking water system, is also receiving greater attention.

Closer to the ‘ideal distribution network’ thanks to modelling and data

The water distribution network – already referred to above – is an essential component of the drinking water provision, along with the water sources and treatment. More than ten years ago, the drinking water utilities asked KWR to begin designing what are known as ‘target structures’ for the distribution network. These target structures show what the ideal distribution network should look like. Since that time, substantial research has been done in this field, according to Ina Vertommen (Team Leader, hydroinformatics) and Karel van Laarhoven (Researcher, water infrastructure). This involved taking a step away from manual design towards automatic design, through the use of numerical optimisation techniques.

Image 5. Hydroinformatics are used for better distribution network design

Little by little, uncertainties were also incorporated into the modelling and, over the course of the latest BTO, an increasingly clear picture was obtained of the transition from the current networks to the target structures. Vertommen: ‘How do we move from today’s networks to the desired network? One has to keep in mind that a distribution network is installed for a period of about 100 years, and that the condition of the current network must be taken into account in decisions concerning its replacement. We conducted condition research and developed increasingly sophisticated models, which also require more and more data. This led to a shift from the actual modelling to the collection of relevant data. This happened in various subprojects in which the drinking water utilities were very deeply involved, so that they could also control the developments closely.’

Major advances were also made in the area of the modelling and prediction of sediment formation in the pipe network, for example. And the increased subsurface busyness referred to above, in combination with the energy transition, naturally also has implications for the design of target structures and the path to their realisation, because, among other reasons, of the resulting higher temperatures in the subsurface.

Hydroinformatics now a fully-fledged research theme

During the latest period hydroinformatics (HI) developed into a fully-fledged theme within the BTO. HI involves the application of information and communications technologies in the water sector. This is highly valuable in facing current and future challenges, and contributes to a more robust and sustainable sector. ‘For example, by developing and making digital techniques available to the drinking water utilities, the latter can generate usable information from data and models, they can better understand and explain processes, their (human or autonomous) decision-making can become more effective, and knowledge can be better preserved,’ says Vertommen.

Hydroinformatics provides a broad basis, but its application is actually often directed at very specific expertises and problems. ‘We conduct for instance generic research on the value-added of machine and deep learning for the water sector. In doing so, we develop knowledge that we can apply to the automatic processing of customer complaints and the identification of microplastics, among others.’

Better integrated asset management

The available data and models in the distribution research make it possible to constantly improve the management of the distribution network. Ralph Beuken (Researcher, water infrastructure): ‘When we speak of asset management, we mean the best possible management of the assets. In the Integrated Asset Management research theme we investigate how to manage one’s assets, from source to tap, as well as possible, and in full alignment with corporate objectives and with a changing environment. In this theme we have further studied risk analyses and decision-making processes, and explored how data about the operation of treatment installations can be made use of to improve management.’ Besides the conducted research, the knowledge sharing among the drinking water utilities also proved to be a considerable added value.

Greater attention to social and communication research besides technology

The BTO originally focused primarily on technical research, but the importance of societal factors and communication became increasingly apparent, and these have also received more BTO attention. Much is technically desirable and possible, but how for example do you get the customer engaged? What do customers think of their drinking water and of the drinking water utilities? What can we do about water poverty? How can drinking water utilities communicate better and more effectively on water use?

Head, heart and hands all play a part in tap-water awareness, according to Nicolien van Aalderen (Researcher, water governance): ‘what do people know about it, how does it make them feel, and how do they actually behave? Insight here is essential – for instance if drinking water utilities want to stimulate people to use less drinking water.’ ‘In this research, serious games have for instance been developed and applied for the organisation of behavioural changes,’ adds Henk-Jan van Alphen.

New challenges

In summary, it can be said that over the latest BTO period new challenges arose, such as the need to address the issue of alternative sources (part of the ‘water transition’), the presence of new pollutants (PFAS, antibiotic resistance), and the consequences of the increased busyness in the subsurface. Since issues present on the drinking water sector’s future horizon are also explicitly examined within the BTO, KWR and the drinking water utilities had already predicted that these questions would arise from and for the drinking water utilities. This is why they were able to respond. ‘That is precisely the power and the importance of a research institute,’ stresses Ruud Bartholomeus.

Research and knowledge transfer with impact

KWR increasingly makes use of modelling to answer the questions raised by drinking water utilities. Good modelling requires the collection of large amounts of reliable data, as well as new and improved analytical techniques, such as non-target screening and bioassays. Furthermore, it has become increasingly clear – as mentioned above – that attention also needs to be paid to the human and management aspects of all technical questions, and to the best communication in this regard.

This also implies that the solutions and the results delivered by KWR are changing. Of course, KWR continues to deliver reliable scientific reports, but research results will also increasingly be expressed through other forms of knowledge transfer that, in the contemporary context, generate a bigger and broader impact – from serious games to short films and other visual material. This is also related to the fact that connections are increasingly being sought with entities other than the drinking water utilities. We need to work together in contributing substantially to meeting the broad societal challenge, in which the drinking water utilities as well as KWR play a role – for example within WiCE, which is connected to the BTO and explicitly seeks collaborations with other parties. Over the next six years the BTO will continue to offer the (drinking) water sector sound solutions for today and for the future.

This same report appeared in H20 magazine.