Multi-stage counterflow washing is most common in plating plants. In this method, water is supplied to the final bath and sent to the previous bathes in turn. Water discharge is from the first bath. Compared with parallel multi-flow washing, this method saves water efficiently. When water has been supplied to all baths, water is stopped and no more water is supplied.
Washing is performed while contamination concentration in the water is monitored.
The first bath is drained regularly or irregularly, to which water is sent from the second bath. The second bath is then filled with water that has been in the third bath. Water is thus transmitted from bath to bath, and the final bath is supplied with tap water in the end. This method saves more water than the multi-stage counterflow method. However, a pump is required to remove or transfer the water.