In the current paper, different MWCNTs filler amounts, containing PA6 and HGBs were prepared by injection moulded. The water uptake at saturation, normalized to the polyamide mass, decreases; hence the diffusion rate in both MWCNTs is slower, respectively HGBs which is faster. Injected moulded polymer samples can take less (6%) water uptake than neat polymer granules (11%). The addition of 15 wt% of multi-walled carbon nanotubes (sample 3) led to a minimum water absorption rate of 5%; this value is 15% less than the majority of the polymer composite mixtures and 1% less than pure PA6, mainly because other polymer composites which contained the HGB filler, absorbed more water. The best results highlight the improved water resistance of polyamide composite (sample 3), which reduces the impact of water on the component and expresses better applicability in the water environment than other polymer composites or even pure PA6.