Everything that appear coloured is due to absorption of light from the visible region. Water does not absorb light from the visible region and hence appeared colourless.
First, water is transparent and not colorless. This is because water has a slight light blue color which a naked eye cannot see because water has a property which make it absorb the blue light and scatter the white light. 

Next, Water doesn't consist of any specific types of bond and groups of atoms which as I mentioned absorbs the blue light.

Therefore, water is transparent and not colorless.