Prior to entering the pump cabinet, water may have to be treated to get the water within the waterjet manufacturer’s specifications. Within the pump cabinet, usually in the lower portion, the water will typically go through one or more final filters just prior to entering the intensifier (number 12 in Figures 15 and 2).

The inlet water must be able to maintain a specified flow rate and pressure to ensure that the intensifier receives enough water. Incoming water must also meet certain requirements with respect to Total Dissolved Solids (TDS), pH, organic matter, temperature, etc. Poor water quality will result in drastically reduced high pressure component life (i.e. anything the high pressure water comes in contact with). Different pump manufacturers require different inlet water pressures, with some needing as little as 30 psi, and others mandating a water pressure booster pump to maintain 100 psi. Water quality will be discussed in more detail in the chapter 4 "Water Quality."