When assessing a water drilling machine, the most critical factors are drilling depth (m) and hole diameter (mm). You must ensure the machine's hoisting capacity and torque are sufficient for your local geological conditions. For instance, hard rock formations require a Pneumatic DTH (Down-The-Hole) hammer system powered by an air compressor, while soil or clay layers are better suited for Hydraulic Rotary drilling with mud pumps. Always verify the engine power (kW), typically from brands like Yuchai or Cummins, to ensure long-term operational stability.