Powershell - Get content between 5th and 6th instance of a character

Question

I'm trying to extract the directory between the 5th and 6th instance of ":" in each line below. I was thinking I would use a foreach loop to iterate through each line of my file and then use substring to grab the path between those characters. Anyone have a suggestion?

FTPAccount1:x:1001:10113:Ryan Murphy:/ftp/sub/Account1:/bin/bash
FTPAccount2:x:1002:10113:Ryan Murphy:/ftp/sub2/Account2:/bin/bash