Wastewater flow samples were collected at 2-hour intervals for one week during the month of October 1998 at the Irtah wastewater pumping station in the Tulkarem city. The station collects about 32% of the wastewater of the Tulkarem city and 25% of the Tulkarem camp. The samples were mixed on 24-hour basis and tested for the pollution parameters BOD5, COD, total suspended solids, orthophosphate, fetal Kjeldahl nitrogen, ammonia nitrogen, nitrate, calcium, sodium and potassium. At the 2-hour intervals the wastewater flow was tested for conductivity, temperature, pH, and dissolved oxygen. The variation of the strength of these parameters and its relation to the flow values are observed and evaluated. The produced organic strength versus the flow and the 24-hour mixed samples are presented and commented upon.