RE9 Water Treatment Plant Walkthrough & Puzzle Solutions
Looking for a complete RE9 Water Treatment Plant walkthrough? The Water Treatment Plant is the fifth area in Resident Evil 9: Requiem, serving as the bridge between the Rhodes Hill region and Raccoon City. This guide covers every puzzle solution, item location, and combat encounter as Grace and Leon fight through this industrial facility. Our RE9 Water Treatment walkthrough ensures you collect everything and solve every puzzle on your first attempt.
What Is the Water Treatment Plant?
The Water Treatment Plant is an industrial facility on the outskirts of Rhodes Hill. After leaving the Courtyard, Grace and Leon enter the plant seeking passage to Raccoon City through the connected storm drain system. The facility is divided into four areas: the intake hall, the filtration chambers, the pump control room, and the storm drain tunnels.
This area is heavily puzzle-focused. The plant's water management systems must be manipulated to open pathways and drain flooded sections. Combat encounters are lighter here compared to the Care Center, but the puzzles require attention to detail. The RE9 Water Treatment Plant walkthrough below provides complete solutions for every puzzle.
📝Puzzle-Heavy Area
The Water Treatment Plant features three interconnected puzzles that control water flow throughout the facility. Solving them in the correct order is essential. Skipping ahead without draining the right sections leaves key items submerged and unreachable. Follow this walkthrough step by step for the best results.
How to Complete the Water Treatment Plant
This RE9 Water Treatment walkthrough follows the optimal path for 100% item collection and efficient puzzle completion.
Step 1: Intake Hall (Grace)
Grace leads exploration of the intake hall. The entrance area is a large industrial space with catwalks above water channels. The main path forward is blocked by a sealed blast door that requires power from the pump control room.
Search the intake hall before proceeding:
| Location | Item | Notes |
|---|---|---|
| Foreman's office | Facility Keycard (Blue) | On desk, required for filtration access |
| Foreman's office | File: Contamination Report | Details infection spread timeline |
| Supply locker | Handgun Ammo (x15) | Locker near entrance, already open |
| Catwalk end | Green Herb | Far end of upper catwalk |
| Under catwalk stairs | Mr. Raccoon #9 | Tucked behind support beam |
Mr. Raccoon #9 is hidden beneath the catwalk stairs, tucked behind a support beam. You need to crouch and look under the staircase from the south side to spot it. Check our Mr. Raccoon locations guide to track your progress.
Step 2: Filtration Chambers and Valve Puzzle (Grace)
Use the Blue Keycard to enter the filtration chambers. This is where the first major puzzle of the Water Treatment Plant begins. Three large filtration tanks dominate the room, each connected to a color-coded valve: red, blue, and yellow.
The goal is to drain Tank B to access a ladder inside it that leads to the pump control room. The valves must be turned in a specific sequence because the tanks are interconnected.
Inside the drained Tank B, find the Pump Room Keycard (Red) on a service platform and Shotgun Shells (x4) on the tank floor.
Step 3: Pump Control Room (Leon)
Leon uses the Red Keycard to enter the pump control room. This is both a puzzle area and a combat encounter. The pump console controls the blast door in the intake hall, but activating it triggers a defense system that also releases four infected from containment pods in the adjacent corridor.
⚠️Prepare Before Activating
Before interacting with the pump console, search the control room thoroughly. There is a typewriter save point, a storage chest, and supplies scattered around the room. Save and organize your inventory before triggering the combat encounter. Leon should have his shotgun loaded and at least one healing item ready.
After clearing the four infected, return to the pump console and complete the activation sequence. The blast door in the intake hall opens, and the storm drain tunnels become accessible.
Key items in the pump control room:
- Weapon Part: Handgun Laser Sight in the supervisor's locker (combination 19-45-72, found in File: Contamination Report)
- Red Herb + Green Herb on the shelf near the storage chest
- Antique Coin #7 inside the ventilation duct above the console (shoot the duct cover to open)
- File: Emergency Protocol on the pump console desk
Step 4: Storm Drain Tunnels to Raccoon City
The storm drain tunnels are the final section of the RE9 Water Treatment Plant walkthrough. Grace and Leon travel through the drains together, heading toward the Raccoon City outskirts. The tunnels are linear but feature several ambush points where enemies burst from side pipes.
Three combat encounters occur in the tunnels:
- Tunnel section 1: Two infected emerge from a side pipe. Leon handles them easily with shotgun blasts.
- Tunnel section 2: Four infected attack from both directions. Grace and Leon fight back-to-back. Use the tight corridor to funnel enemies.
- Tunnel section 3: One bloated infected blocks the exit. This enemy explodes when killed, so maintain distance and use handgun shots to detonate it safely.
At the tunnel exit, a cutscene plays as Grace and Leon emerge into the outskirts of Raccoon City. The atmosphere shifts dramatically as the familiar cityscape comes into view, setting up the next major arc of the game.
Water Treatment Plant Collectibles
Verify you have all collectibles before entering the storm drain tunnels. The Water Treatment Plant cannot be revisited after entering the drains.
- Mr. Raccoon #9 under the catwalk stairs in the intake hall
- Antique Coin #7 in the ventilation duct above the pump console
- File: Contamination Report in the foreman's office
- File: Emergency Protocol on the pump console desk
📝Last Chance for Rhodes Hill Items
Entering the storm drain tunnels is the final point of no return for the entire Rhodes Hill region. If you missed items in the Care Center, basement, or courtyard, you cannot retrieve them. The Water Treatment Plant itself also locks once you enter the drains.
Frequently Asked Questions
How do I solve the valve puzzle?
Turn the valves in this order: Red, Yellow, Blue. Wait for the water level indicator on Tank B to drop below the red line after turning the Yellow Valve before turning the Blue Valve. If you make a mistake, reset all three valves and start over.
What is the supervisor's locker combination?
The combination is 19-45-72. The code is written in the margin of the Contamination Report file found in the foreman's office in the intake hall.
Where is Mr. Raccoon #9?
Mr. Raccoon #9 is under the catwalk stairs in the intake hall, tucked behind a support beam. Crouch and look under the staircase from the south side to spot it.
Can I return to the Water Treatment Plant?
No. Once you enter the storm drain tunnels, the Water Treatment Plant and the entire Rhodes Hill region are sealed off permanently. You can only revisit these areas in New Game Plus.
Head to the RPD & Orphanage walkthrough for the next chapter, or go back to the Courtyard walkthrough to review what you might have missed.