The colour will vary with the film (including the format) and, to a certain extent, the choice of chemistry. It may even vary with pH if you are doing water rinses.
I pre-rinse all my black and white film before adding the developer (a choice that is somewhat controversial) and the colour of the pre-rinse water varies considerably with the film. My guess is that the initial colour comes from the anti-halation dies added to the sub-strate.
My favourite pre-rinse colour is the beautiful cyan tinged dark blue I get when I develop 120 Plus-X .
While some of the colour creating agents are removed with just a water pre-rinse, others will not become evident until you are further along with the process.