Why would the water be a red or rust color and like filmy at the cove joint in a basement?
Color of some soils (mud).
Likely due to water penetration and rust (Iron Ochre).
Afternoon, James. Hope this post finds you well.
Iron ochre has a rust like appearance. At times the goo is a thick jell.
Was there a sump pit? If so, was the water stained?
Any images?
Welcome to our forum, James!..Enjoy! 
Yep, probably iron ochre.
Every shallow body of water or small stream looked that way in the Pine Barrens of NJ. There’s “Iron in The Pines”
Thank you my fellow inspectors. Here are some pictures. I guess there is no real solution to this problem.
