Generally the colour of water relates to what lies beneath or to its surroundings - the colour of the sky or overhanging trees, for example. However, sometimes it is an unexpected tint. In the photograph above the green doesn't seem to correspond to any reflected objects but does sit nicely as a complement to the buff of the reeds and the blue of the cloudless sky. In fact had the green not been there I probably wouldn't have taken the shot.
photo © T. Boughen Camera: Sony DSC-RX100
