Why does the gas from dry ice flow down? I am reading Dan Broughton's answer in replying to the question "why does the gas from dry ice flow down" here. 

According to the answer, the fog is water's color and water is condensed and suspended in the CO2. 
Do you agree with this answer? If so then should water have color? I see some documents saying that it is nearly colorless. 


  Why does the gas from dry ice flow down?
  
  Dry ice is simply the common term used for solid carbon dioxide (CO2),
  so the gas coming off of the dry ice is CO2 gas. CO2 gas has a density
  of 1.96 kg/m^3 and air (78% N, 21% O2) is 1.29 kg/m^3. Since the CO2
  is more dense, it sinks in air.
  
  But CO2 is colorless, so what makes it appear as a white mist? As the
  gas sublimes (change directly from solid to gas), it comes off of the
  dry ice at -78.5 C (-109.2 F).  Being well below the freezing point of
  water, any moisture in the air surrounding the dry ice condenses and
  is suspended in the CO2, creating the cloud/fog effect that we can
  see.
  
  These two phenomena combined are what create the fog that flows along
  the ground.
The gas flows downwards because it is more dense. It is more dense both because $\ce{CO2}$ is heavier than $\ce{N2}$ and $\ce{O2}$ and because the gas is colder than the ambient air.

The mist is water in the surrounding air condensing into microscopic droplets due to the lowered temperature.  The amount of mist depends on the humidity of the air; in perfectly dry air there will be no mist.

All of the gases involved are colourless. The mist appears white because it is in small particles and so it scatters any light falling on it.  It is the same colour as "natural" mist and for the same reason.