In order to investigate the stabilisation of the octahedral Al site through water molecules, six water molecules were added to the FAU_fwAloct_2Al model. This was done by means of auxiliary force field simulations, which are described in more detail in sections S1.1 and S1.2 (Supporting Information). Five low-energy snapshots were extracted from the simulation results and optimised with DFT. The structure having the lowest energy was then taken as starting point for the AIMD simulations.