While analyzing the water structure, we find that different water molecules are surrounded by different numbers of co-solvents, along with other water molecules. The successful numbers of co-ordination of a central water molecule are calculated using the geometric criteria of hydrogen bonding. We have taken all donor-acceptor possibilities into account that could potentially form a hydrogen bond. Different modes of hydrogen bond formation for water molecules are provided in the supplementary information for a better understanding (Table ). The numbers vary between 2 and 3 justifying the presence of bi or tri coordinated water molecules. Similar results were found when the effective hydration number of choline was monitored in aqueous choline chloride solutions by Shaukat et al. The average hydrogen bond numbers in the ternary mixtures considered in the present study are influenced by both choline and urea molecules and a properly designed similar experiment, on the mixtures with higher reline wt% can in principle confirm the presence of bi and tri coordinated water molecules. The formation of a proper tetrahedral water structure requires four hydrogen-bonded partners but it is evident that successful tetra coordination (blue bar) is maximum in the case of W-UC (4:2) which is 20% of the total hydrogen-bonded network. The value of the contribution of tetra-coordinated water molecules for the W-UC (8:4) system is less than 5% and as a result, the microscopic water structure deviates severely from tetrahedrality. In Fig 9, we have also considered the penta coordinated (sky blue bar) central water molecules but it shows a negligibly small contribution, and therefore not considered here.