When you're decently far into the quest chains of Arc Raiders, you'll slowly start learning about the past where humanity defeated the first wave husks. As you get further into the quests, you'll also start getting some tasks to help the general public, and these will mostly be given to you by Celeste.
Water Troubles is one such example of the quest. When you go to Celeste to claim this, she'll ask for your help to check out the waters in Dam Battlegrounds since she's getting some complaints over the quality. To do this, you'll have to visit a specific tunnel on the map.
Where To Find The Flood Access Tunnel
When you receive the Water Troubles quest in Arc Raiders, you'll first be asked to get to the flood access tunnel under the Red Lake Balcony. You can find this balcony by zooming in on the eastern side of the Dam Battlegrounds map, just above the Testing Annex area. To get to this tunnel, you first have to drop closer to the red lake down below.
When you're close to the red lake, you'll see a giant hole in the wall while looking at the Research & Administration building from the eastern side. This hole is the flood access tunnel, and it's big enough to make it quite hard to miss once you're in the area. As soon as you enter this tunnel, the quest will get updated.
How To Sample The Water
The second part of this quest asks you to sample the water in the flood access tunnels. To do this, go through the entire tunnel until you reach an open area with some ropes that'll lead you up. However, instead of taking these ropes, keep going to the other end of this open area near the smaller hole to the left.
As you get close there, you'll notice a yellow interaction spot on the ground where you can sample the water. As soon as you interact with this, the quest will come to an end and you can take your rewards once you leave the raid in any way.
