Water jet cutting, according to the internet, is done at about 50,000-60,000 psi. If that's correct, it's significantly higher than the pressures at those depths. I'm not sure though if a pinhole would concentrate the pressure and make any difference.
There is a small one that Conjet makes that goes up to 3000bar, or 43511.32psi (according to the converter). Since the cutter goes up to 3000bar, I assume it can cut concrete at lower pressures. But that's for cutting concrete.
And now that I think about it, I believe something is added to the water of a water cutter to make it more "cutty" (yes, that is the technical term :hihi:)