The explosion wouldn’t be as bad as you are thinking. You can’t compress water so while you can hold it under huge amounts of pressure, should the vessel fail it will usually fail slowly (relatively speaking) because there is no explosive expansion of the liquid inside. Even if the vessel fails catastrophically and rapidly it will just rip open and spray water all over the place. 

The types of explosions from high pressure you are thinking of is because the pressurized item has its volume significantly reduced compared to its volume at standard pressure. So the explosion is actually caused by the rapid change in volume when the vessel fails. Something goes from taking up 1 cubic foot to 100 cubic feet instantly and anything in its displacement path gets smacked. But the pressurized water doesn’t do that. It goes from taking up 1 cubic foot to still taking up 1 cubic foot so there is no expansion and no displacement of anything.  

Think water balloon popping vs air filled ballon. (Which isn’t a perfect example since the balloon material wants to reduce in size when it fails so it will spray the water around more). The water balloon will largely just splash it’s water in a small area while the air fill balloon makes a bang sound and blasts bits of itself all over the place. 

Those things like water rockets or hot water heaters exploding are due to gas being compressed inside the vessel (you pump air into the water rocket and the water heater creates steam inside). 

The most dangerous aspect would probably actually be a small leak as then you might be faced with a high pressure jet of water shooting out in a thin stream which may be able to cut thru another object.