To better understand why water appears to have no color we must first understand that, what humans can see is a tiny dot in the electromagnetic spectrum. That narrow range of frequencies (in the vicinity of 400nm-700nm), is the only part of the electromagnetic spectrun visible to the human eye. It includes every color we are able perceive and it is all we are able to see.
When a material is hit by light (frequency) if any of that frequency absorbed by the material falls into the visible region, it will appear as coloured to us.
If a material absorbs all of the visible spectrum of light, then it appears to us as black. If it doesn't absorb any part of the visible spectrum of light, then it appears as transparent when light is transmitted through it, or white when it's scattered.
Water doesn't have the ability to absorb any part of the visible spectrum of light and thus, it appears to be transparent to us.
Yes water is colourless during to the molecular it's make-up of. Water has two elements which are hydrogen and oxygen. This two elements are gases in nature and are not visible. Again, any colour you see is actually that wavelength of length which was not absorb by that particular substance was the one that reflect back to your eyes thereby you see the colour. On the other hand, water don't reflect back any colour the only one I knew of is just little blue colour.... On actual sense water is colourless but water become deeper blue as thickness of the observed sample of water increases. This is cause by the selective absorption and scattering of white light.
Read also https://www.quora.com/Why-water-has-no-colour