The Clean Water Experiment

Use of Water by Citizens Increases as Water Quality Improves

Waternet - waterboard of the Amsterdam region

Water quality in Amsterdam ( and in other cities in Europe (EEA, 2016) is improving as a result of a decrease of industrial activities and water management measures such as improved wastewater treatment.

Currently in Amsterdam the water quality is better than it has ever been before. An important reason for this is that all houses are now connected to the central sewage system. Although the building of a centralized sewage system began in the nineteenth century, wastewater from the houses along the canals was flushed through these canals until 1987. Another improvement of the water quality came with the relocation of the wastewater treatment plants outside of the city. The canals no longer contain wastewater OR treated wastewater. As a result, the water quality is good enough for swimming on most days. It is only shortly after extreme rain events (about five days a year) that there is an overflow of the sewage system. After such events it takes about three days for the water system to recover.

Surf recreation at the canals of Amsterdam
Water expert during the Amsterdam CitySwim 2017

Citizen Science in Amsterdam – The Clean Water Experiment

Waternet - waterboard of the Amsterdam region

Citizens are increasingly using surface water for swimming, canoeing, or watering their garden.

Information and knowledge for the general public is, however, limited. In Amsterdam, in the summer of 2017, a few hundred citizens monitored the famous canals, urban lakes, rivers and ditches in their city. They assessed the water quality using a specially designed Waterbox. Results were regularly reported on the online platform of The Clean Water Experiment and directly visible to all participants and the general public. The citizens assessed the clarity, colour, temperature, odour, and taste of the water. Observations of birds and macrofauna, visual contamination (plastics, waste) and presence of E.coli-bacteria were also included in the monitoring protocol.

The Waterbox, Photo by Pavel van Houten

Who Are These Citizen Water Researchers?

Waternet - waterboard of the Amsterdam region

Participants of the experiments have been recruited via flyers at supermarkets, social media, and local media. Most of them are between 36 and 55 years old, but there are also a few older than 65 and children younger than 15. Many participants have performed the experiments together with relatives, neighbours, friends and passers-by.

Participants: “At first glance, the water seems dirty, but in the end it appears to be relatively clean”

“My reason to join the project is to find out if we (family) can swim in this canal. After heavy rainfall it appears not to be a good idea at least. The petri-dish showed that the limits are exceeded 7 times”

“To me, the project showed the transparency of Waternet. They are open in what they do. That is appreciated”

“A very nice experience: you have a totally different relationship with the water, and see more details of the water and its environment”

Participants for The Clean Water Experiment
Participants for The Clean Water Experiment
Participants for The Clean Water Experiment
Photo was taken by Wilbert van der Heijden

Citizen Science Increases Awareness and Knowledge


At the start of the project, most participants indicated that they had limited to no knowledge on water quality.

After the project, 74% stated that their knowledge level on water quality has increased as a result of participation in The Clean Water project. 15% of the participants changed their behaviour with respect to use of the water; they either increased or decreased their swimming in open water and fishing activities. Several participants report that they use the water more frequently for recreation (hiking, cycling or relaxing, boating and canoeing or Stand Up Paddling).

Judgment of the Water Quality in the City of Amsterdam by the Participants in Green (good), Orange (moderate), and Red (bad) Dots on the Map
Initial Knowledge Level of Participants on Water Quality
Increase of Knowledge by Participants