When evaluating waterproof fabric, you must prioritize the Hydrostatic Head (HH) rating, which measures water pressure resistance; for professional outdoor gear, a minimum of 10,000mm is recommended. Additionally, check the Moisture Vapor Transmission Rate (MVTR) to ensure breathability, typically ranging from 5,000 to 20,000 g/m²/24h. For durability, verify the denier (D) count of the base polyester or nylon and ensure the Durable Water Repellent (DWR) coating is PFOA/PFOS free to meet modern safety standards.