How come the water is not infected?

[nikvoodoo]

and the other thing is zombies cant just "rip" flesh out of the pile, they lack claws, so they must have used their teeth right? or they took the whole body with them

I've ripped a chicken breast off a whole uncooked chicken without claws... Same principle. Human fingers can tear flesh off bone if you use enough force and find the correct spot.

I think that just gives testimony to how rapid the infection is, and goes along with my theory. Fresh fluid from an infected creature (alive/undead at the time, whatever - still moving lol) transmitted to a new host via broken skin...
Not canon per the story revealed so far, but thinking logically - the aftermath of their indoor battles had to have been gory messes, blood and goo sprayed everywhere. Yet the cleanup crew is never infected. What are the odds that not one of them touched wet blood during cleanup? Pretty slim. I
...Yet our heroes who swam in the goo came out OK despite getting fluids in direct contact with eyes and mouth (Riley did both, spitting and wiping her face). Hence, the agent becomes inactive or dormant over time.

You brought up the answer in your own response. Broken Skin. Tommy turned because he had a cut from a pipe bomb explosion. There was no indicated injuries or broken skin from Riley and Angel when they immersed themselves in the pile. Same can probably be said for clean up crews. So long as they don't have an open wound, you can touch the blood. You just probably shouldn't.

Am I saying there's no chance the virus/pathogen dies when outside the body? Not at all. That could very well be the case. And that could explain (getting back to the point of this thread) why the water doesn't get infected. All I'm saying is there is no real evidence saying the pathogen dies when it leaves the body yet. We haven't seen it in action enough to rule out the possibility it's like bacteria that grows exponentially in the right conditions.