The relationship between the adsorption of water on MIL-53 (Al) MOF, the structural phase of MIL-53 (Al), and the quadrupole coupling constant of ²⁷Al framework aluminium atom (QCC) of the MOF AlO₄(OH)₂ centres (Al-sites) has been investigated by combining solid-state ²⁷Al MAS NMR spectroscopy with XRD analysis and DFT calculations. It is established that ²⁷Al QCC is primarily sensitive to water adsorption to the Al-sites and by a minor extent to the framework contraction/expansion interconversions. We thus conclude that the ²⁷Al MAS NMR method is sensitive enough to differentiate the effects of pore contractions and water adsorption to Al-sites basing on the changes of the QCC value.