Hydro‑Puzzle is a mid‑game side quest in Dying Light: The Beast that starts after helping Pietro in “Cable Guy.” The setup is simple: Town Hall’s taps have gone dry. Your job is to check the pumping station, trace the blockage through municipal infrastructure, and deal with what’s actually jamming the flow.

Start at the pumping station

Head to the pumping station and ignore the infected milling outside. Enter from the back through the broken window beside the parked truck. Inside, vault the railing and inspect the main pump to read the water pressure. The gauges are fine, which rules out a surface‑level failure and points you downstream.

Waterworks Repair Facility: get the Chief Engineer’s key

Travel to the Waterworks Repair Facility. On the building’s left side, climb the ladder and platforms to the roof, then crawl through the rooftop vent to get inside.

  • Drop into the upper offices and locate the Payroll Manager’s room adjacent to where you enter.
  • Open the desk safe to retrieve the Chief Engineer’s key. The safe’s combination is 27‑01‑15. Note: if that fails on your build, try 27‑01‑06.

With the key in hand, clear infected at the ground‑floor entrance, unlock the Chief Engineer’s office, and review the plans. The fault traces to a sewer maintenance point back in Old Town.

Sewer maintenance point: follow the pipes, not your instincts

Pick the lock on the maintenance door and listen for a clanging echo in the pipe runs. Drop through the open hatch and start tracking the sound by following the yellow‑painted pipes.

  • From the drop, take an immediate right along the yellow piping into a low crawlspace. Watch for an exploding infected in this stretch.
  • Optional loot room: look for a ground‑level vent leading to a locked room. Inside is a safe with a UV‑marked clue on nearby surfaces. The combination is 21‑69‑35.
  • Continue beneath the ceiling pipes and turn right at the corridor’s end to reach another crawlspace marked by yellow paint.

That crawlspace splits. The right path houses a Volatile. Take the left path instead to emerge into a safer hallway. Move to the open doorway stenciled with a large “4” and climb the ladder. You’re now close to the source.

Clear the chamber and make contact

The banging inside the pipes is coming from survivors barricaded above the chamber. Before you can reach them, you’ll need to thin the horde in this section.

  • Prioritize the Screamer on the upper level to stop the aggro loop.
  • If your Beast Mode is charged, spend it early to stabilize the fight.

Unlock the exit and disable the traps

Use the Chief Engineer’s key to open the exit for the survivors — they’re a family, and the father previously ran this site. Push forward and clear the next pocket of infected.

In the corridor ahead you’ll see electrified floor plates. Don’t sprint through them. Instead, enter the vent on the left and throw the switch inside to cut power safely. From there, guide the group upward through the stairwell to the offices.

Step outside to rendezvous with Elena and Nolan, who confirm water is flowing to Town Hall again and head back down to evac the family.

Rewards

  • 10,000 XP
  • Bruiser Arm Protectors
  • Beginner Training Manual ×2
  • Co‑Op Lootbox (only when playing in co‑op)

Safe combinations used in Hydro‑Puzzle

  • Payroll Manager’s desk safe (Chief Engineer’s key): 27‑01‑15 (try 27‑01‑06 if the first code doesn’t register)
  • Sewer stash safe (optional room via vent): 21‑69‑35

Tips

  • Controller method for safes: with vibration enabled, rotate the dial slowly and feel for a distinct rumble on correct numbers. Be aware the dial also buzzes at “50,” which is a common false positive.
  • UV checks: when you suspect a safe clue nearby, sweep walls, lockers, and notes with your UV light; some markings only reveal under UV.
  • Route discipline: stick to yellow‑marked pipes underground — they’re your breadcrumb trail and the fastest way to the objective.
  • Threat management: clear Screamers first; they extend fights and amplify risk. If you see a Volatile in the right‑hand crawlspace, backtrack and take the left path as intended.
  • Travel time: there’s a vehicle near the pumping station if you want a quicker hop between sites.

Fast checklist

  • Enter pumping station via rear window, verify pressure is normal.
  • Waterworks roof vent → Payroll Manager’s safe (27‑01‑15 → key) → unlock Chief Engineer’s office.
  • Old Town sewer maintenance point → follow yellow pipes → optional safe (21‑69‑35).
  • Door “4” ladder → clear chamber → use key on exit.
  • Vent left to disable electric plates → escort path to offices → meet Elena and Nolan.

Hydro‑Puzzle reads like busywork at first, but the route teaches the game’s visual language — painted navigational cues, UV‑only clues, and utility kill‑switches — in a tight loop. If you’re hunting XP and reliable gear mid‑campaign, it’s time well spent.