Questions and answers about PFAS in water

Can we swim safely in ditches, canals and ponds?

Taking a dip on a hot day? Wonderful. You can, but not everywhere. It is best to swim at an official swimming location in the area. We check our locations at least once every two weeks during the swimming season (May 1 - October 1) for pathogenic bacteria and blue-green algae. However, when it is very warm, the water quality of the swimming water can change quickly. Before swimming, please check for the latest information on www.zwemwater.nl, via the ZwemApp or on the signs at the swimming location. 

HHNK conducts water quality measurements at officially designated swimming water locations. The results can be found at www.zwemwater.nl. In addition to the regular measurements for bacteria and blue-green algae, the 15 HHNK swimming water locations were examined for PFAS in 2024. At all locations the values are below the swimming water advisory values. The results can be found on the website of the Province of North Holland. 

How does the presence of PFAS in surface water affect the quality of drinking water in Hollands Noorderkwartier?

The surface water in our area is not used by any drinking water company to make drinking water. The RIVM website has more information on PFAS and drinking water.

Where does PFAS contamination come from?

PFAS can be found everywhere: in ditches, canals, ponds but also in the soil. Because the substances do not degrade, they remain present in our living environment for many years. PFAS contamination is caused by contamination via discharges from wastewater treatment plants (WWTP), overflows or discharges from industry and by the use of firefighting foam, for example. 

What measurements are carried out in Hollands Noorderkwartier?

  • HHNK dredges ditches, streams and canals. This is how we prevent flooding during heavy rainfall. Dredging is the mud that lies on the bottom and we always carefully check it for PFAS. More than 99% of the checked dredge is reusable. If it contains more PFAS than is allowed by law, it is taken away to specialists. The specialists store the PFAS-contaminated dredge in large, sealed depots in the ground or clean the dredge. See the Dredging page. 
  • HHNK monitors various substances in surface water within the WFD monitoring network and also conducts research on PFOS dispersion. 
  • HHNK also monitors PFAS in wastewater. Nationwide research is being done on the removal of PFAS in treatment plants. We follow this research closely.
  • HHNK has investigated 15 swimming water sites for PFAS in the past period. 

Other questions

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