Water is a polar molecule because of their bonding structure. For a bond to be polar, two atoms would not equally share a pair of electrons. Imagine two toddlers playing with a toy, with one of the children acting like a bully and playing with the toy more.
Water is made up of 2 hydrogens and 1 oxygen (H2O), with the oxygen atom monopolising the electrons. The oxygen is said to be electronegative as it is more negatively charged, thus attracts the single electron of each hydrogen. In addition, water could not be formed in a linear structure as the hydrogen atoms would have to be at the same side of the oxygen atom, in order for it to “share” the electrons. Therefore, water is a polar molecule due to the way it’s structurally bonded.