In general, waterjets are quite safe. The nozzle is typically 0.1" (3 mm) or so from the material, so it is difficult to get your fingers under it. High pressure tubing does not explode because water is not very compressible. When a leak occurs, the pressure quickly drops to a safe level.

That said, like any machining tool, there are hazards to working with a waterjet. You should refer to the manufacturer's material for complete safety information. The information provided here is basic and does not cover all the potential hazards and should not substitute for carefully reading the safety information provided by the manufacturer of the waterjet.

Beware the waterjet stream
Remember that the waterjet stream can cut through 2" steel, so it will make short work of any body parts you place in front of it. It is a very dangerous cutting edge. Always take care before turning on the machine to make sure that no body parts are in the way.

Eye protection
You can put splash guards on the nozzle and cover it with rags and you will still get the occasional splash of water mixed with abrasive. You do not want to get abrasive in your eye—although it's inert, it's still abrasive and will irritate your eyes and possibly scratch your cornea.

Motion control system
The motion control system precisely positions the nozzle at various locations on the table and can move at up to 100 inches per minute (2.5 meters per minute). Don't let body parts get between the nozzle and a solid object or they can be crushed.

Ear protection
When you are cutting above water always wear ear protection. The water exits the nozzle at about the speed of sound and makes a lot of noise—enough noise to damage your hearing. When cutting underwater, the noise level is much lower, but depending on your shop environment, you may still want to use ear protection.