2025 swimming season starts May 1

Next week, the 2025 swimming season begins. It runs from May 1 to October 1 for most swimming locations. There are two locations where the swimming season lasts until Sept. 1. During this period, swimming water quality is measured and analyzed each month by the Water Test Foundation on behalf of the Water Board. In total, we perform measurements at 31 swimming locations in our management area.

The measurements examine various parameters important to bathing water quality. These include blue-green algae, which can be toxic, and various bacteria, including E-coli. In addition, transparency, temperature, pH and the like are measured. 

If blue-green algae or bacteria exceed certain values, we advise the Province of North Holland on whether or not to institute a warning or negative swimming advice at the location in question. The province consults with the manager of the location about placing warning signs. 

If something is wrong with the bathing water quality, measurements are taken more often to keep a good finger on the pulse. For example, measurements are taken every week instead of once a month until the water quality is back to normal. On www.zwemwater.nl you can see the results of measurements and whether there is a warning or negative swimming advice. There is also an app for this.