Quick Answer
Find the Water Treatment Building, approach from the north or swamp side, and stay outside. The Flood Spill Intake is the concrete-walled pool where the building meets the swamp. Enter the polluted water, find the rusted yellow barrel leaking toxic fluid and interact with it. Complete the objectives in one raid; once the interaction registers, the quest is done and extraction is optional.
Source of the Contamination Requirements
Complete Water Troubles and have Dam Battlegrounds access. You do not need to bring an item or survive extraction, so a free loadout is a sensible choice.
- Finish the objectives in one raid.
- Approach from the north or swamp side to avoid crossing the building interior.
- Nothing needs to be carried out after the barrel interaction.
The Full Water Chain, in Order
The water chain runs Water Troubles, Source of the Contamination, Switching the Supply, then A Warm Place to Rest.
The sequence follows Celeste's work on Speranza's contaminated water supply and the steps needed to investigate, reroute and stabilize it.
Where to Find the Flood Spill Intake
The Flood Spill Intake is on the north or back exterior of the Water Treatment Building, facing the swamp. Look for a small pool of polluted water enclosed by concrete walls and ramps, level with the surrounding swamp.
- Find the Water Treatment Building first.
- Circle to the north or swamp-facing side instead of entering.
- Use the concrete walls, ramps and polluted pool as the confirmation cues.
- Step into the intake area to advance the location objective.
This is also the intake used again in A Toxic Trail, so remember the north-side route.
How to Investigate the Suspicious Object
The suspicious object is the rusted or yellow barrel sitting in the intake water and leaking iridescent toxic fluid. Approach it and use the interaction prompt.
The interaction completes the investigation at the intake, and dying afterward does not undo the quest. Other flooded areas on Dam Battlegrounds are irrelevant to this objective.
How to Extract Afterwards
Extraction is optional, but the Central Swamp Lift is the nearest convenient exit, a short walk north from the intake. Check the area before committing because a Rocketeer can patrol around the lift.
While you are already in the swamp, watch for Great Mullein and mushrooms used for crafting and Scrappy progression.
Source of the Contamination Rewards
The quest grants crafting materials when turned in. Check the reward panel after completion for the exact item mix and quantities shown on your current build.
What Comes After Source of the Contamination
Switching the Supply unlocks after Source of the Contamination. The follow-up moves the water storyline to Spaceport and uses the underground tunnel map layer, which is the key navigation tool for that quest.
Frequently Asked Questions
Where is the Flood Spill Intake in ARC Raiders?
It is on the north exterior of the Water Treatment Building, where a concrete-walled polluted pool meets the swamp.
Do you need to enter the Water Treatment Building?
No. The intake is outside on the north or swamp-facing side, and approaching the exterior area advances the objective.
Do you need to extract for Source of the Contamination?
No. Once the suspicious barrel interaction completes the objective, quest progress is secure even if you do not extract.
How do you unlock Source of the Contamination?
Complete Water Troubles first.
What does Source of the Contamination unlock?
It unlocks Switching the Supply.