Power to X (PtX) is becoming an established method to store the excess renewable power into green hydrogen through water electrolysis. Hydrogen can be used to produce electricity in fuel cells, as fuel, or further refined into ammonia or methanol. However, a crucial aspect in water electrolysis is the purity of water, that must have very low electrical conductivity (< 5&#956;S/cm), to avoid corrosion and shortening of the electrolyser’s lifetime. Moreover, its high pure water consumption demands finding a sustainable, reliable, and non competitive water source, for instance seawater or reclaimed municipal wastewater. Within the various technologies to obtain such water quality, membrane distillation (MD) is gaining more and more interest, as it is a thermal-driven process able to reach 100% salinity rejection.