BlueCircles: The urban transition towards a decentralised grid of circular water systems

6 min read

If we tell you that fresh water is the most precious resource on earth, would you agree?

Healthy urban water systems are fundamental for our lives. We need them to secure food and drinking water production, clean air, social and economic welfare, even for our health and happiness. But because of climate change and rapid population growth, cities are challenged to keep the water infrastructure uptime.

By 2100 the entire urban water infrastructure could be transformed into grids of decentralised circular water systems. In the future, the urban water demand will be supplied by local water sources including stormwater, surface water, grey water and wastewater, gradually upgrading the current discharge and supply networks.

From linear to circular urban water systems

The growing urban population, together with more intense rainfall and longer droughts, impose major challenges to the existing urban infrastructure and the liveability of our cities. More people living in the city means a higher demand for freshwater, more paved area to be discharged and more wastewater is generated. Enlarging the current centralised urban drainage and supply networks as remedy is expensive and labour intensive.

BlueCircles offers a flexible and decentralised model to effectively and gradually upgrade the traditional urban networks for water supply and discharge. The growing paved surface is used as catchment area to collect rainwater run-off. Collected water is treated and stored locally, through small scale water systems, reducing discharge to the municipal network. The stored water is used to meet the local water demand. These small scale circular water systems can be implemented as addition to the existing infrastructure, in urban retrofitting or development projects, enabling the urban transition to greener, cooler and water resilient cities.

Local water sources for different applications

1. Stormwater is collected where it falls, within project boundaries, reducing discharge to the municipal sewer.

2. Water is supplied from local sources, close to the end-users, avoiding large transport and distribution networks, and enabling customised water supply.

3. Water is treated through autonomous nature-based systems, adapted to the available water volume and necessary quality.

4. Urban infrastructure is flexible for expansion to manage and minimise the impact of extreme fluctuations in water availability.

5. Water is visible in the public space, enhancing liveability.

Implementing our bluebloqs technology offers an opportunity to keep stormwater in the neighborhood, creating a local source for water supply and reducing discharge to the treatment plant.

BlueCircles as key opportunity to:

  • Gradually upgrade ageing water infrastructure

  • Ensure a safe, healthy and pleasant living environment

  • Adapt to climate change and rapid urbanisation

  • Reduce drinking water footprint

Autonomous water systems

Separated water flows at the source to enable reuse: 

Since the 19th century, centralised water supply and drainage systems have become inherent to urban development: every building conglomeration is accompanied by kilometers of piping network for collecting, distributing and supplying water from the natural source to, the most dominant, final discharge at the treatment plant. Water supply and drainage are generally provided and managed independently from each other, through disconnected infrastructure. Decisions on how water is supplied are made by the management authority, generally without consultation with the users on the receiving end.

This centralised model has led to an one-fit-all approach in which stormwater is discharged through the sewer; traditionally through a combined sewer with wastewater. In most serviced areas in western Europe, high quality potable water is provided through the tap, which is mainly produced from groundwater and surface water. The supplied water is used for all urban applications regardless the required quality.

With BlueCircles, there is more emphasis on the integration of water management with urban development. The separation of water flows -stormwater, greywater and wastewater- occurs at the local scale, allowing the production from local water sources, and of water of different qualities, customised for the specific application.

The most important condition for local water reuse is that the water can be purified into clean water that meets all requirements for the specific application. Suitable sources for local water production must also meet other requirements, including affordability, adaptability to the local environment and feasibility of storage and extraction.

Autonomous and selfregulated water systems

Emerging technologies for local water treatment and reuse offer promising opportunities to enable a flexible and decentralised urban water system.

Bluebloqs is a nature-based system that combines bio-filtration and deep infiltration techniques for stormwater collection, treatment, storage and reuse in urban areas: a compact bio-filtration system is designed as a green feature, and the purified water is stored in the subsurface, from where it can be retrieved for different urban applications, e.g. irrigation, industrial processes or combating urban heat.

From a linear and difficult to adapt urban water cycle…

In the traditional practice, when a development project takes place, a large part of the supply and discharge networks needs to be adjusted or replaced. A costeffective alternative is to create a discharge and supply point within the project area, aimed at solving local effects while avoiding the need for long distance of long distance intervention and linking direct with the users.

To a shorter and resilient water cycle.

The shift to autonomous and self- regulated water networks that operate at a building, community or cluster level independent of the wider grid, requires a change in legislation and building regulations to enable smaller- scale applications in water collection, storage, treatment and distribution.

Urban transition to greener, cooler districts

BlueCircles envisions a decentralised grid of circular blue-green water systems integrated in the urban landscape, replacing the current urban infrastructure for water supply and drainage in new developments or retrofitting projects. The impact on the local context include aesthetic betterment and increase of public health by adding green and cooling. Wider impact at system level includes flexibility of the urban infrastructure and optimisation of water resources. 

The transition towards greener, cooler and water resilient cities starts at the local level with water at the core of new developments, such as buildings, sewer replacement or public space. These paved areas which often become inhabitable during hot summer days, offer the opportunity for small scale interventions that integrate green and water, creating green spots in the city, the so called urban pockets. This blue-green network is flexible, resilient and adaptive to future population growth and uncertain climate events.

You can download the Bluecircles vision by clicking the following link:

200115 BlueCircles Vision_publicatie_v06.pdf