Apply a thin layer of PVC cement to the pipe end of a PVC garden hose adapter.
Place the glued end of the fitting into one end of a PVC pipe.
Apply a thin layer of PVC glue to the pipe side of a PVC jet nozzle fitting, and press it into the other end of the pipe.
Screw the garden hose into the garden hose adapter.
Point the nozzle end of the pipe at the ground, holding it straight up and down over the spot where you want to bore the hole.
Have a helper turn on the water for the hose, making sure to open the valve all the way.
Steadily and slowly press the nozzle into the ground. The water pressure will clear away dirt, blowing it out of the hole as you press further down. Continue pressing the PVC into the ground until the hole reaches the desired depth, then retract the PVC pipe from the ground.