mcgregor is right. water is non compressible. this is why we use hydraulics to move heavy shit. its all in physics. and the only way that could be dangerous is if the water pressure itself squirted out through a pinhole in the weld and cut you like a razor.
pressure in = pressure out.
hyrdaulics was fun in college.
example: see the water come exploding out? or does it stay in place? you decide.