On this website you will always find the latest information on the quality of bathing water in Katwijk: http://www.zwemwater.nl/ Possible messages are: - Good: There are no reports for this swimming spot. You can safely swim. - Warning: Swimming allowed, however there is a potential health risk. - Advice against bathing: Not swimming, health risk. - Swim Ban: Swimming prohibited, great health risk. During the bathing season (May 1 to October 1) local provinces will inform you about the quality of the water of the official bathing sites. The measuring point is the place where most bathers are expected either where the risk of pollution is greatest. Outside the bathing season, the bathing water is not investigated. If you go into the water off season, you must decide for yourself whether it is justified.