Every Drop Counts Against Drought
Circular Water Network Antwerp
The city of Antwerp is combating drought and water scarcity with an innovative circular water network.
By purifying and reusing surface water that would otherwise be lost, the city reduces the pressure on drinking water supplies, keeps urban greenery healthy, and addresses historically low groundwater levels.
Sweco is studying the development of two circular water pipelines, contributing to a climate-resilient city.
- Client
- City of Antwerp
- Location
- Antwerp
- Expertise
- Hydraulic infrastructure, integrated water management, climate adaptation, water purification
- Stakeholders
- water-link, ZOO Antwerpen, AG Vespa, Vlaamse Milieumaatschappij, Aquafin
Climate change increasingly brings extreme weather conditions. Therefore, it is important to prepare for this. During dry periods, the use of drinking water for irrigation or filling swimming pools may be temporarily prohibited. Drought also leads to empty city ponds, low groundwater levels, and more heat in urban areas.
In Antwerp, there is an additional risk during extremely dry periods when brackish Scheldt water infiltrates the groundwater table. This brackish water displaces the fresh groundwater, adversely affecting urban greenery and damaging the foundations of buildings and other structures. Urban greenery is essential to keep Antwerp cool during hot summers.
Purified Wastewater for Urban Greenery
To combat drought and save precious drinking water, a feasibility study was conducted on the development of a circular water network. This new water network would form a second water circuit for the city, alongside the existing drinking water circuit.
This pipeline network will be fed by permanent dewatering and surface water from the river Groot Schijn. This water is currently pumped towards Lobroekdok, ending up in the harbor where it becomes brackish (and unusable). This circular city water network will provide water for parks, ponds, public greenery, and fountains, and can also be used as greywater for large public buildings.
Biodiversity and Groundwater Benefits
This new water network offers numerous benefits. Antwerp saves a lot of drinking water, and green areas receive sufficient water, allowing urban greenery to grow better and healthier. This helps combat urban warming, creates a healthier living environment with more biodiversity, and improves groundwater levels.
Surface water that would normally be pumped to the sea and thus become saline and lost can be purified and reused in the city. It is estimated that we can recover 3,500 m³ of water daily, equivalent to about 25,000 swimming pools per year (an average pool contains 50 m³). This water can be used in the following ways:
- Replenishing the groundwater table: to keep groundwater levels stable and prevent soil dehydration.
- Irrigation for urban greenery: purified water for parks, irrigation water for public greenery, replenishing fountains.
- Greywater for large public buildings: for applications such as flushing toilets.
Multidisciplinary Support
To get all that water where it is needed, transport pipelines are required. This creates a circular city water network with various circular water pipelines (CWLs). Sweco is closely involved in the development of two of these pipelines: CWL South and CWL Schijn.
Each has a different source: a large dewatering station of the Antwerp Ring, which currently discharges into the Scheldt, and the river Schijn, which is pumped to the Albert Canal. Both CWLs will eventually flow into an urban pond, aiming to balance it and maintain groundwater levels in the city center. Additionally, branches will be made to other users, such as parks, developments, ZOO Antwerp, and tapping points for the green service.
Sweco supports from sketch design to execution. With our multidisciplinary team (hydraulic infrastructure, integrated water management, climate adaptation, water purification), we assist the city of Antwerp with design and stakeholder management. Due to the complex urban context and maximizing coupling opportunities, we adopt a flexible approach. For certain sub-projects, we work on the preliminary design, while others have already accelerated and are in the environmental permit application (OVA) and tender phase.
Technical Implementation with Minimal Disruption
The circular pipeline network is constructed in accordance with a drinking water network. A pumping station is placed at the source to maintain pressure in the circular water network. To withstand the pressure, the pipelines are made of ductile iron (main axis 200 mm, side axis 50 mm). Difficult crossings are carried out with guided drilling, and where possible, we lay the pipelines in open trenches.
Preferably, we do this when the street is already open for, for example, a heat network or other utility works. Or we use existing underground ducts, such as the sewers, in which the pipeline can be suspended. This way, we minimize disruption for residents during construction.
Who is Involved?
The city of Antwerp is the driving force and leading partner, fully committed to circular water use. Along with the city, other involved partners are working on the project: sewer manager and drinking water supplier water-link, ZOO Antwerp, autonomous municipal company AG Vespa, the Flemish Environment Agency (VMM), and water purifier Aquafin. The rollout of the circular water network is also supported by the Flemish government and the European Union.
This initiative is part of a program by the Flemish Environment Agency, which is part of the Blue Deal.
The Blue Deal is a program launched by the Flemish Government in the fight against water scarcity and drought. The program includes more than 70 actions and 400 projects. With the Blue Deal, Flanders is moving towards less hardening, more wetting, and maximum circular water use.
