Water is blue, and not because of reflection or scattering or any of that; it’s blue just because it is. That’s not much of an explanation though. The more scientific version is that its blue because it has an absorption minimum at the blue end of the visible part of the electromagnetic spectrum. It absorbs more of the other colours and lets a little more blue through for us to see. Only a little more though, which is why you need a swimming pool’s worth of water to notice.