Low-temperature waste heat is abundantly available across many industrial processes worldwide, yet a significant portion of this energy remains unused. At the same time, many industrial facilities—particularly remote sites handling brackish water—require sustainable water purification solutions to meet zero liquid discharge (ZLD) and minimal liquid discharge (MLD) targets, as well as to provide reliable freshwater for personnel and operational needs. In our recent research, waste heat from a hydrogen liquefaction plant was integrated with a direct contact membrane distillation (DCMD) desalination system to enable sustainable water purification. A comprehensive parametric analysis was conducted to evaluate the effects of feed Reynolds number, permeate mass flow rate, membrane module length, and heat exchanger pinch temperature on the thermal and economic performance of the hybrid system. Both parallel and series multi-stage DCMD configurations were investigated. In addition, multi-objective optimization was performed using the levelized cost of water (LCOW) and daily water production as objective functions, yielding optimal values of 1.75 $/m³ and 29.8 m³ day⁻¹, respectively. The results demonstrate the strong potential of coupling industrial waste heat with membrane distillation to sustainably produce freshwater, enabling industrial facilities to convert unused thermal energy into valuable resources while advancing net-zero and water sustainability goals.