Experimental study of any supramolecular structures in bulk water is difficult because of their short lifetime: the hydrogen bonds are continually breaking and reforming at timescales faster than 200 femtoseconds.
Nevertheless, water clusters have been observed in the gas phase and in dilute mixtures of water and non-polar solvents like benzene and liquid helium. The experimental detection and characterization of the clusters has been achieved with the following methods: far-infrared spectroscopy|far-infrared (FIR), vibration-rotation-tunneling spectroscopy|vibration-rotation-tunneling (VRT), Н-NMR, and neutron diffraction. The hexamer is found to have planar geometry in liquid helium, a chair conformation in organic solvents, and a cage structure in the gas phase. Experiments combining IR spectroscopy with mass spectrometry reveal cubic configurations for clusters in the range n=(8-10).
When the water is part of a crystal structure as in a hydrate, x-ray diffraction can be used. Conformation of a water heptamer was determined (cyclic twisted nonplanar) using this method. Further, multi-layered water clusters with formulae (HO) trapped inside cavities of several polyoxometalate clusters were also reported by Mueller et al.