The water loading in the zeolite system was found to have a sizable impact on the predicted chemical shift, with the magnitude of the effect being as much as 3 ppm and heavily depending on the position (T-site) of the aluminium atom in the framework. The 27 Al chemical shift in zeolites also varies with temperature and water loading, with a steady decrease for higher water loadings due to enhanced water mobility. This observation strongly suggests that the presence of water molecules has a significant impact on the local aluminium environment, contradicting one of the rationales for using background charge and dehydrated models. Additionally, increased Al content can shift the 27 Al chemical shift by over 4 ppm, complicating NMR spectral assignments in zeolites with low Si/Al ratios and numerous inequivalent T-sites.