After you've dropped down into the underground Cistern area in Amnesia: Rebirth you'll be tasked with making your way down to the bottom of a giant well. Around halfway down you'll find two openings in the wall, and a large gap that you'll need to cross in order to proceed. There's a water tank nearby that can be positioned as a bridge of sorts, here's how to move it and solve the Cistern water tank puzzle.
Amnesia Rebirth Cistern water tank puzzle solution
To make your way down the Cistern area of Amnesia: Rebirth you'll need to cross a gap by moving a water tank. First, make your way down to the controls opposite the hatches. There are three wheels here that you can turn. One opens and closes the hatches, one moves the water tank left to right, and one moves it up and down. Start by positioning the water tank in between the hatches, as shown in the image below. Make sure the hatches are open and make your way to the nearest one.
Drop down to the first hatch and then use the water tank to reach the next one. Enter this second hatch and follow the path around to the left. You will find a corpse blocking the first hatch from opening. Clear the blockage and exit through the unlocked hatch.
Make your way back to the control wheels. Close the hatches and then move the water tank to the right and up. You can see marks in the walls where the tank can be moved. Move it up to the top of the rightmost vertical track. Let go and open the hatches, the water tank will fall onto the second hatch. The water tank should now be positioned like it is in the image below.
All you need to do now is head back through the first hatch and take a left, as the second hatch is now blocked. You'll make your way through a tunnel and end up at a hole in the wall. From here you can use the water tank to cross to the next platform and leave the area. You're now well on your way to the next area, which features a secret laboratory.
That's how to get through the Cistern section in Amnesia: Rebirth. For more on the game why not check out Alice Bell's review. Elsewhere there's our look at the increased level variety found in Amnesia: Rebirth.