Shock waves produced during electro-hydraulic drilling can be reflected into a rock body where the reflected shock waves are converted from compression waves to tension waves, which are more efficient at breaking down the rock body. A system configured for electro-hydraulic drilling where shock waves produced during drilling are reflected into the rock body includes two electrodes and a shock wave reflector disposed at an electro-hydraulic drill head. The two electrodes are configured to (1) facilitate formation of a spark along a spark path spanning the two electrodes and (2) facilitate a pulse of electricity being passed through the spark to form a primary shock wave emanating from the spark path. The shock wave reflector is configured to reflect a portion of the primary shock wave such that the reflected shock wave is concentrated to a focal region within the rock body.