Pick up a metal lead pipe and beat it

You grab a lead pipe that was conveniently placed by the wall and raise it above your head ready to attack whatever was lurking in the darkness. A hand reaches out from the darkness and tries to grasp your ankle but before it can do so you bash it on the head with your weapon. It stops what it is doing, stunned, as you bash it in the head over and over until blood runs into the water. You take a closer look at what the thing was; It was a zombie, crawling around in the darkness. You breathe a sigh of relief and continue forward.

You start to see a distant flicker of light in the distance. As you get closer you can see that it is a flashlight that has been discarded. You find it unnerving that someone else could also be down here. The light flickers on and off looking like it's going to run out of batteries at any moment. You pick it up and look around the place. You are relieved that you finally have light even if it flickers constantly. You continue forward once again down the sewer tunnels.

You eventually come to a two-way split in the tunnels.

The one on the left has a bright red colour in the water which you can presume in blood.

The one on the right is very dark and even when you point your flashlight down the tunnel it does not illuminate much. Then you start to hear something from down that tunnel. Chanting is heard.