A pulsating water jet (PWJ) offers advantages over a continuous water jet, such as lower liquid volume flows and pressures for deeper cuts. However, traditional PWJ setups are unsuitable for minimally invasive surgeries due to their size. This study aimed to develop a PWJ instrument by testing a 100 mm long, 10 mm diameter extension tube. We evaluated (1) the machining capability of the PWJ with the extension tube on simulated hard tissue and (2) the impact of a submerged environment on cutting capacity. Using a 20 kHz ultrasonic pulsating water jet were provided erosion 120 tests in bone cement and assessed cutting depth and volume via micro-CT scans. Results showed that the PWJ with the extension tube could machine bone cement in both open-air and submerged environments, though the latter required longer exposure and reduced material removal by 65%. Increasing exposure time improved cutting depth and volume until a plateau was reached. The PWJ was compared with a continuous jet with a 5-minute exposure time, showing no visible or measurable erosion. This PWJ design could meet requirements, offering non-thermal and selective tissue removal.