In this paper, the pinch point(s) and the freshwater target(s) are investigated for water-using networks with single contaminant. A new method is proposed to determine the pinch point(s) based on the features of the pinch point before target calculation. With the known pinch point, it is only necessary to carry out detailed calculation for the allocation of the pinch-source stream(s) to the demand stream(s) just below the pinch, in the freshwater target calculation. This reduces the calculation effort, especially for the networks with many streams. The results of this work agree with that obtained in the literature.