Nature-Based Solutions by Drinking Water Supply Company PWN
We spoke to Ruud van der Neut, senior drinking water engineer and project manager, and researcher Tim de Groot about the LIFE WATERSOURCE project - led by PWN. Their work focuses on pioneering nature-based solutions to strengthen the ecosystem of Lake IJsselmeer, ensuring sustainable drinking water and resilience against climate change, salinization, and emerging contaminants.
PWN is the primary drinking water supplier for the province of North-Holland. Over 70% of the drinking water which is produced by PWN has as source water from Lake IJsselmeer. This source is increasingly under pressure due to climate change, leading to more frequent extreme weather events such as drought, heavy rainfall, and extreme heat waves (KNMI 2023). These conditions impact both the quantity and quality of the water in Lake IJsselmeer. Predictably, the likelihood of scenarios where the annual average water becomes too saline for the drinking water production, like the dry summers of 2018 and 2022, is increasing. Future projections (2050) anticipate salinization events every 8 years and water shortages every 5 years, according to the stress-test for the IJsselmeer area in 2021 (Pouwels et al 2021). Furthermore, the surface water of Lake IJsselmeer poses challenges to purify due to the presence of suspended solids and organic material in the water, as well as the increase in contaminants of emerging concern (CECs), like pesticides, PFAS, microplastics and pharmaceuticals. Also, the likelihood of water quality deterioration (such as algal blooms) due to a combination of climate change and insufficient ecological resilience is increased. On top of this, PWN can expect an increase in customers of 300.000 households due to new housing projects. To address these challenges, initiative-taking climate adaptation measures are essential.
Climate Buffer Lake IJsselmeer
The Klimaatbuffer IJsselmeer (KIJ) project, or ‘Climate Buffer Lake IJsselmeer,’ proposes a system of deep-water storage basins surrounded by a natural purifying landscape to support PWN’s drinking water production. These interconnected basins, approximately 25 meters deep with variable water levels, serve to pre-purify water and
final treatment step using bank filtration in which a — typically applied along rivers but here integrated within a still-water basin — exemplifies a nature-based solution to enhance water purification efficiency. The KIJ concept integrates these natural pretreatment methods, although their full potential and optimal configurations remain to be explored.
“The LWS project proposes a groundbreaking approach to ensure a secure, sustainable drinking water future for North-Holland, aligning human activity with broader ecological goals by using nature-based solutions where possible and technical solutions where necessary.”
increase storage capacity, giving PWN greater flexibility in selectively sourcing high-quality water from Lake IJsselmeer. Sediment from the basin excavation will be used to create this surrounding purifying landscape, which enhances local ecology and contributes to additional water filtration. The gradual land-to-water transition around the KIJ boosts biodiversity in Lake IJsselmeer and can possibly offer recreational spaces for the community in the future. The natural purified water is stored in the deep-water basins, where a
Demonstration Project: LIFE WATERSOURCE
Part of this exploration is the LIFE WATERSOURCE (LWS) project. Demonstrating the Climate Buffer Lake IJsselmeer concept is essential to ensure a secure, climate-resilient drinking water supply for North-Holland according to senior drinking water engineer Mr Van der Neut, water quality engineer and project manager. With climate change introducing greater variability in water availability, salinization, and emerging contaminants, a small-scale
Demonstration Project LIFE WATERSOURCE
A test landscape for the natural pre-treatment of Lake IJsselmeer water
To ensure a reliable drinking water supply in the future, PWN aims to strengthen Lake IJsselmeer, its main water source. With the Climate Buffer Lake IJsselmeer, we want to develop a large natural purification area. Before scaling up, we conduct small-scale research through the LIFE WATERSOURCE demonstration project. This helps us understand how to make the area work best, for both people and nature. We are happy to show what we are researching and how we do it.
3. Two Purifying Landscapes
1. Inlet Structure
We pump water from Lake IJsselmeer into the research area.
The water is divided between two purifying landscapes with different characteristics, vegetation, and maintenance strategies. This helps us determine which works best.
a. River Landscape A meandering landscape with dense vegetation of purifying plants.
b. Marsh Landscape A shallow, diverse wetland with many shorelines and elevation differences, creating more space for ecology.
Fish Siphon
A fish siphon passage allows fish to swim in and out of the purification landscape. We study whether this improves their spawning behaviour, as fish prefer to spawn in shallow waters with dense vegetation.
We monitor which fish pass through and whether young fish thrive
test is needed to validate the effectiveness of nature-based solutions as pretreatment for drinking water before wider adoption.
The LWS project - a one-hectare demonstration site incorporating mussel zones, purifying landscapes, constructed wetlands, and bank filtration —provides a controlled environment to rigorously test and refine these natural techniques The use of nature for pre-purification is particulary exciting as it represents a new, sustainable approach for drinking water treatment.
According to Mr De Groot, researcher on this project, the demonstration is particularly exciting as it represents a controlled environment where innovative techniques can be rigorously tested and fine-tuned for fullscale implementation. Data collected during the demonstration will provide critical insights for future projects, helping to integrate naturebased solutions into drinking water.
The LWS project proposes a groundbreaking approach to ensure a secure, sustainable water future for North-Holland. According to Mr De Groot and Mr Van der Neut, this shift is not only about safeguarding drinking water but also about aligning with broader ecological goals, ensuring that human activity uses nature-based solutions where possible, and technical solutions where necessary.
5. Bank Filtration
An important step in the natural purification process is bank filtration.
Pre-treated water slowly percolates through a layer of special sand, removing the last particles and bacteria. We test three methods: one within the river landscape and two at the end of the purification process. The results are compared.
Filters
After passing through the purifying landscapes, the water undergoes extra treatment in helophyte filters where purifying plants grow. Their roots absorb nutrients like nitrogen, while the sand filters out small particles. We test two flow methods and compare the
Operation and Function of LIFE WATERSOURCE
The LWS demonstration focuses on understanding and optimizing natural purification processes under realistic and variable environmental conditions. As Mr De Groot explains, the influence of different retention times, maintenance regimes, and seasonal factors on water quality improvements within various nature-based systems will be studied.
The data collected will feed into a digital twin—a dynamic, virtual model continuously updated with monitoring data. This digital twin enables predictive modeling, scenario testing, and potential replication. It supports real-time operational adjustments for the LWS system while informing future large-
scale implementations, ensuring they are both robust and adaptive.
Operationally, LWS replicates and enhances natural filtration pathways in ways that support both water quality and ecological integrity. Mussel zones, for instance, remove suspended solids and algae, while helophyte marshes, submerged vegetation, and mudflats capture nutrients and organic matter. At the same time, these features create habitats for a diverse range of aquatic life and encourage a broad spectrum of flora and fauna to thrive. Constructed wetlands, with a horizontal and vertical flow, are designed to enhance purification and target dissolved organic carbon, nitrogen compounds, and micropollutants. Lastly, a bank filtration step provides a final polishing phase, improving the microbial stability of the water by removing potential fecal-derived microbial contaminants associated with fauna present in the purifying landscapes. Together, these interventions align seamlessly with the Climate Buffer’s vision: improving robustness of incoming water thereby reducing chemical inputs, enhancing ecological resilience, and ensuring that water management strategies remain closely tied to the natural processes that underpin a sustainable future.
Cooperation with other European countries
Collaboration is a cornerstone of the LWS initiative, and its partnership with Spanish organizations highlights the benefits of international cooperation. Partners like Aquatec and Cetaqua (water technology institute) and Aigües de Barcelona (drinking water company) bring valuable expertise in water management and ecological solutions. By pooling knowledge and resources, the project leverages diverse perspectives to refine methodologies and enhance outcomes. This cross-border partnership
project promotes sustainability while lowering costs on the long term. The demonstration phase will provide valuable insights into the scalability of nature-based solutions, setting the stage for the full-scale implementation of the Climate Buffer Lake IJsselmeer initiative. By harmonizing human needs with ecological stewardship, it offers a blueprint for sustainable water management that can be replicated worldwide. This project can provide the most valuable insights for regions grappling with similar challenges, demonstrating the power of innovation, collaboration, and ecological harmony.
“The demonstration phase will provide valuable insights into the scalability of nature-based solutions, setting the stage for the full-scale implementation of the Climate Buffer Lake IJsselmeer initiative and promoting sustainability while lowering long-term costs.”
also fosters innovation and ensures that the project’s findings have broad applicability across Europe. According to the Spanish partnership exemplifies how shared goals and collaborative frameworks can lead to stronger, more effective solutions.
Project Expectations
The LWS project is expected to deliver transformative outcomes says Mr Van der Neut. By reducing reliance on chemical treatments and enhancing biodiversity, the
The LIFE WATERSOURCE project is supported by the EU LIFE Grant, a funding mechanism designed to promote environmental and climate action projects across Europe. This subsidy underscores the project’s potential to serve as a model for sustainable water management solutions, not only for NorthHolland but also for regions facing similar challenges. The EU’s financial backing also reflects the significance of collaboration and innovation in addressing environmental challenges at a continental scale.
How Can We Improve the Drinking Water Supply in North-Holland?
Drinking water company PWN has three key objectives that address the urgent need for change in water management practices.
• To reduce the demand for drinking water by encouraging more efficient use. This includes reassessing the role of drinking water in industrial applications and exploring alternatives to minimize unnecessary consumption.
• To increase the region’s capacity for water purification and production to meet growing demands. By leveraging innovative methods, the project seeks to enhance the efficiency and resilience of water treatment processes.
• To focus on increasing storage capacity combined with strengthening the ecosystem. This involves integrating natural pre-treatment methods that use ecological processes to purify water. The Climate Buffer Lake IJsselmeer and therefore the demonstration project LIFE WATERSOURCE are contributing to the third objective.
LIFE WATERSOURCE
Demonstrating a Climate-Resilient Drinking Water Source, Adopting Nature-Based Solutions
Project Objectives
The LIFE WATERSOURCE demonstration showcases innovative nature-based solutions for the pre-treatment of Lake IJsselmeer water to ensure its suitability as a sustainable drinking water source. The project integrates multiple components, including mussel zones, purifying landscapes, constructed wetlands, and bank filtration. LIFE WATERSOURCE aims to demonstrate sustainable, scalable solutions for water resource management in the Netherlands and beyond.
Project Funding
The LIFE WATERSOURCE Project is cofunded by the European Union’s Life Program. Project 101113621.
Project Team Members
• Ing. Ruud van der Neut
• Dr. Tim de Groot
• Dr. Koen Zuurbier
• MSc. Anne Swank
• MSc. Myrthe Fonck
Contact Details
Dr. Tim de Groot
T: +316 574 207 50
E: tim.de.groot@pwn.nl
W: https://www.pwn.nl/watersource
Ing. Ruud van der Neut
T: +316 512 594 94
E: ruud.van.der.neut@pwn.nl
W: https://www.pwn.nl/watersource
Dr. Tim de Groot Ing. Ruud van der Neut
Dr. Tim de Groot is a researcher at PWN, focusing on water and naturerelated projects. His expertise includes biogeochemical processes in natural environments, particularly their role in water quality and climate change resilience. Ing. Ruud van der Neut is a senior drinking water engineer and project manager at PWN. His expertise as an engineer includes monitoring and safeguarding the quality of (drinking) water with a focus on contaminants of emerging concern in water sources and water treatment steps.
