The water filter with 1,9cm (3/4 Zoll) external thread is integrated in the irrigation system to inhibit clogging of the drip pricker, due to little particles in the water. The water has to pass the filter, so the little particles get caught on the sieve and the quality of the water will be improved. Now and then you have to clean the sieve of the water filter. Thereto you can take the lid of and rinse the sieve unter running water. "Mesh" indicates the filter strength. The bigger the value, the finer the filtering.