I actually didn't see how many miles you said are on the vehicle, but I would just replace the WP if it were me. I think an Aisin WP on Amazon is like $75. If you've already drained and filled it and you're just draining out contaminated water but not coolant, I would just pour it in the...
That water still looks pretty crummy to me. I would suggest a *gentle* backflush. I don't recall which hose you want to disconnect at the firewall, but you can search for that on Mud. Just be sure to use gentle pressure, there is another Mudder that is convinced he blew his HG by flushing his...