Water sometimes flows in unexpected directions

Chunk Update?

Unable to reproduce. This does not occur for me. Might be a lag issue that slows or stops a block update causing it. When you place the block it makes the water blocks update finishing what it should have done. Weird though that it happened at ever corner of your golem farm.

@Th3F4114n0n3

I can't reproduce it consistently either. In some places it happens (every single time), in others it doesn't. It's random and unpredictable as far as I can tell.

I attached more screenshots of another example showing a similar glitched behavior but slightly different to the first example. As you can see it's again direction-independent, and it happens on every level of that tiered structure... except on the bottommost one, even though that one is as identical as any of the others.

(It's not a golem farm, by the way, it's going to be just a simple passive mob farm (zombies, skeletons, creepers & witches) when it's done.)

I don't think lag has anything to do with it because this is all in singleplayer and, like I said, it happens consistently (in certain places).

*Ah..!*

Signs have something to do with it. If I place signs in the empty 2x2 column in the center where the mobs are to fall down, the glitch disappears (after I remove the water and replace it, that is). In fact, this is why the bottommost layer, which had signs in the center, wasn't exhibiting the same behavior as the other layers before.

The flowing water "path-finding" logic sees signs as solid blocks so in this case it's as if the water is spreading across a completely even surface (ignoring the slabs) with no holes. *Without* signs it sees the 2x2 hole and "wants" to travel only along the shortest path(s) to the hole, leaving those weird gaps. It's slightly unintuitive because either way the water source blocks are 7 blocks away from the hole, so they can't reach it in any case.

Also, that sort of explains the second example but doesn't solve the mystery of why the water spreads so awkwardly in the first example.

I attached a world save and MCEdit schematic of the structure so anyone can test it for themselves. (Sorry, I don't have the structure from the first example anymore). ON/OFF switch for the water bucket dispensers is at the bottom.

Still in 07a

Is this still a concern in the current Minecraft version 1.7.9 / Launcher version 1.3.11 or later? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.

Is this still a concern in the current Minecraft version 14w30c or later? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.

Just tested this in 14w30c and it's still there. Attached a 6-second video.

I posted a similar response to a potential duplicate (MC-76857) of this bugreport, but this might clear up some things about this bug here too.

Expected behaviour:

Unwanted behaviour:

I've placed down lapis blocks where the water should have flowed, but because of the two holes in the back, the algorithm thinks water should go down there.

Confirm for 1.9.3 pre-2

Confirmed for 1.9.4

Confirmed for 16w20a

Is this still an issue with all the water changes?

Confirmed in 1.15.2 and 20w20b.

Also affects lava.

Can confirm in 20w48a.

This might be happening since water always flows to the nearest hole.

Can confirm in 21w05b.

Affects 1.21

I'd like to request ownership of this report, considering it has not been consistently maintained with new affected versions, and the original owner has not been active for 4 years.