The best way to control water absorption and diffusion in composites is to prevent or minimize them in the first place. This can be achieved by using proper design, material selection, and manufacturing processes such as choosing resins, fibers, and fillers with low water absorption and diffusion coefficients, high hydrophobicity, and high compatibility. Additionally, applying coatings, sealants, or barriers that protect the composite surface from water ingress and reduce permeability of the composite material is important. Controlling curing conditions, pressure, and temperature to ensure complete polymerization, reduce voids and cracks, and improve interfacial bonding between the fiber and the matrix is also necessary. Quality control and inspection should be performed to detect and repair any defects that can facilitate water absorption and diffusion. However, even with these preventive measures some water absorption and diffusion may still occur during the service life of the composite parts, especially under harsh environmental conditions. Therefore, it is also important to monitor and maintain the composite parts regularly using NDT methods to assess their moisture content and diffusion rate. Corrective actions should be taken such as drying the composite parts to remove excess water or replacing or repairing parts that have reached their critical moisture level or have suffered severe degradation. Modifying or optimizing operating conditions or parameters to reduce exposure or stress on composite parts may also be necessary. By using these methods you can ensure quality and reliability of your composite manufacturing operations while extending service life and performance of your composite products.