Watermonsters

Watermonsters by Waterland vzw was a large-scale citizen science initiative engaging citizens in Flanders and Brussels to measure the quality of local rivers, canals, streams, and ditches. The project arose from a serious environmental problem: water quality in Flanders is in a critical state. Only one of 195 watercourses met all official quality standards, while about 8,000 overflow points released untreated sewage into waterways. Around 400,000 homes—10% of all households—were not connected to the sewage system, causing major harm to nature, public health, and quality of life.

To tackle this, Waterland vzw collaborated with KU Leuven, De Standaard, Natuurpunt, and Bond Beter Leefmilieu to create Watermonsters, enabling citizens to contribute to scientific research. Participants received sampling kits and collected water from nearby streams or canals, testing for Escherichia coli (E. coli), a key indicator of contamination from untreated wastewater.

In spring 2025, a monitoring network of about 6,000 sampling points was set up across Flanders and Brussels. Supported by scientific institutions, companies, and civic groups, roughly 5,000 citizen scientists conducted measurements over several months, yielding more than 5,700 usable data points.

The results were striking: about 43% of sampled locations met the Flemish Environment Agency’s swimming water standards, while 42% showed high E. coli concentrations, indicating significant pollution. Larger navigable waterways generally scored better than smaller creeks or ditches, likely due to improved sewage infrastructure.

Watermonsters successfully merged citizen engagement with scientific rigor. By turning environmental monitoring into a neighborhood activity, it made water quality issues tangible and personal. Participants gained firsthand insight into local pollution, helping make the state of Flemish waters visible not only to scientists and policymakers but to everyone—from families at home to decision-makers in boardrooms.