There are several different types of prepared, conditioned or contaminated water in addition to naturally occurring water such as freshwater, sea water, brackish water and sour water. Water is usually only slightly corrosive and, under normal conditions, there is usually no need for any special precautions with regard to pump materials. Exceptions are sea water, demineralized water and certain types of industrial wastewater. In these cases we must consider how the water may corrode the selected materials.