TLDR: Follow the slices while constantly spamming attempts to build a well. "Water runs too deep" means there's nothing on that tile. Usually the rod points to nothing so if you're running in circles, move to a new area and start over. Sticking to low elevation might help.
The rod shows pie slices, which supposedly indicate direction and distance (the thinner, the closer?) of nearby source tiles. The rod's range feels like 10-20 tiles, so the readings are pretty much right next to you and you don't have to walk far.
By constantly moving in the direction of each slice you see, you will gravitate toward a possible source. You know you're in the middle of it when you see slices pointing in all directions. The rod seems to point to a random source tile every time, so it varies constantly.
Attempting to build a well seems to be the only way to check for a water source on a tile. So spam a lot of wells, constantly. Put the command to build a well on your hotbar - just drag it over. When you try to build it, it will probably fail for one of these reasons:
- "Can't build here" if it's on soft ground. Find a different biome.
- "Ground not flat enough" if it's too uneven.
- "Water runs too deep" if there's no water source.
Most of the time you will find nothing. Maybe 90% of the time the rod directs me to an area with zero source tiles. So don't spend too long on one spot. Spam a bunch of wells and if you don't find anything, move on.
I've only successfully found four sources so far. One was a tiny chain of three tiles. Another was maybe ten tiles long but only 1-2 tiles wide. Another was a large irregular shape, 10x10 or more in area. They're like streams with varying length and width. I suggest spamming a few wells around loosely in case it's a big one, then comb by checking every other tile, or every tile if you want to be thorough.
Elevation might be important. Two of the spots I found were close to shore and another was in a valley between two cliffs. After that I was exploring a cliffy area and found almost nothing on the whole biome. As an experiment, I raised a source tile that was close to shore by piling 1.4 meters of dirt, but I could still build a well on it.
Side note: Sometimes you can build a well on uneven ground by changing the way it's facing. The game checks two tiles for flatness: the tile the well is on PLUS the tile under the well's crank (to the right of the well, from your character's point of view).
Good luck, post your findings!
