High pressure 304 or 316 stainless steel tubing (number 10 in Figure 11) is attached to the outlet of each check valve. Common outer diameters are 0.25", 0.313", 0.375" and 0.563". Inner diameters range from 0.062" to 0.312". There is usually a flexible protective covering around the tube.

The high pressure tubing from the left hand high pressure cylinder will join together at some point with the high pressure tubing from the right hand cylinder. The high pressure tubing carries the pressurized water to the pressure attenuator. Additional high pressure tubing will channel the high pressure water to the cutting head.

The length, number of bends and other obstructions to flow (e.g. hand valves) in the high pressure tubing path must be taken into consideration when designing a high pressure waterjet system. Pressure will drop with each bend in the tubing. Also, as the distance between the pump and the cutting head increases, internal friction of the water as it drags against the inner walls will generate heat resulting in a loss of water pressure. This topic will be discussed in more detail in the Chapter 5 "Pressure Drop in Tubing."