How does our water flow?

30 May


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Thomas Craps

Energy & Utilities Consultant


min. read

Every day we open our taps at home and see clear and clean water flow out of it. After we are done using the water for whatever purpose we need (drinking, cooking, cleaning, …) we see it flow down the drain. But how did this water get to our house and what happens with it when it leaves via the drain? In this article we will explore the different parties involved, the role they play and where the water sector is going in the near future.

Who does what?

From the tap, the different drinking water companies:


The service of providing drinking water is split between a small number of companies which are mostly region based. Even though the number of providers is limited there is still a push for more consolidation (read more below).

Note: As of January 1st the companies Pidpa and water-link will merge to become “Adelta”, making it the biggest producer of drinking water in Flanders. The new company will service over 1.850.000 consumers in 69 cities and municipalities in the province of Antwerp.

Processing of drinking water:

  • Inflow: water from a waterway flow into the facility.

  • Adding saturated water: through air bubbles all dirt is transported to the surface. Slit is then scraped off and transported to a separate tank (this can be used to make cement).

  • Dubble layer filter: This filter consists of 2 layers (hydro-anthracite, rhine sand) that capture all dirty particles.

  • Active coal filter: In this filter all traces pesticides and pharmaceuticals are filtered out.

  • UV disinfection: The water flows through a reactor with different UV-lights the remaining germs are deactivated.

  • Outflow: Via pumps the clean drinking water is transported to the households.

Down the drain, the different sewage treatment companies:


The landscape for sewage treatment companies is very different from the drinking water companies as seen in the image above (some overlap can be found). This patch work has grown historically with all the issues connected to this (read more below). To mitigate the existing issues a considerable amount of consolidation is required in trend with their drinking water counterparts.

Processing of sewage water:

  • Mechanical purification: crude waste is removed from the water (leaves, sand, paper, …).

  • Biological purification: biological degradable materials are removed from the water (nitrogen and phosphorus).

  • Post-purification: slit sinks to the bottom which causes the creation of an upper layer of purified water. This purified water is sent to the Flemish waterways.

Aquafin and its role?

In Flanders, drinking water companies have a sanitation obligation for the drinking water they supply to end-users. They must ensure that this water is also purified after use before it is discharged back into nature. To fulfill this sanitation obligation, drinking water companies have an agreement with Aquafin, which is compensated by them for this purification. The fee for sewage treatment is passed on to consumers by the drinking water companies through the water bill. In addition to this supra-municipal sanitation fee, there is also a municipal sanitation fee for the construction and maintenance of the municipal sewage infrastructure.

In the past, drinking water companies themselves set up a 'sewerage branch' so that they, like Aquafin, became active in the municipal sewerage management market.
However, the practice proved to be inefficient. Because in this way, all those parties must develop and safeguard the same knowledge, while Aquafin has so much knowledge and experience from its supra-municipal mission.

Moreover, municipal and supra-municipal projects are often intertwined, and there is no 'hard' dividing line between the 2 systems. Furthermore, they impact each other. That is why Aquafin advocated for a more integrated sewerage management, which is also confirmed in the new cooperation agreement with the Flemish Region by the role of matchmaker assigned to Aquafin.

Expanding the network, Riopact:

For the Flemish Region, Aquafin builds and optimizes the supra-municipal infrastructure necessary for this. Cities and municipalities can also rely on Aquafin for this. More than one in three local authorities collaborate with Aquafin for municipal sewage management. They do this either directly or through collaboration with drinking water companies water-link, Pidpa, and De Watergroep (Riopact). Given the strength of collaboration with a drinking water company, Aquafin will henceforth only approach cities and municipalities within such collaboration.

Professional support can be provided in multiple ways. This can include:

  • legal and financial advice;

  • administrative support;

  • project management support.


The future?

Even before being assigned the above mentioned role of matchmaker, Aquafin had been structurally collaborating with drinking water companies water-link and De Watergroep (aforementioned Riopact) in the municipalities within their drinking water supply areas that also chose to outsource sewer management. A structural collaboration agreement had also been agreed with Pidpa since June 2023. Meanwhile, they have already started in 4 Pidpa municipalities, but from 2024, there will be many more added since Pidpa and water-link have merged.

Within all these partnerships, the constant factor is that each party does what it is good at.
In practice, this means that the drinking water company maintains direct contacts with the public (e.g., house connections), while Aquafin is responsible for investment projects and vision formation (hydraulic advice, stormwater and drought plans, etc.). The pooling of resources should lead to more efficient use of resources and thus a better outcome for people and the environment.

With a view to further consolidate the water sector, there are currently also discussions underway with Farys. Already in the city of Aalst there is a collaboration ongoing.

Need help to navigate the waves of changes? Let's talk!

Trilations is ready to use its 15 years of experience in the water sector to support our clients in navigating these waves of challenges and change. Via data analysis, asset management, business analysis and process optimization we can be a valuable partner in this transformation.

Avatar picture

Thomas Craps

Energy & Utilities Consultant


min. read