Water will not work, sorry.. they will either die or tp away depending on existing damage.
but what is stopping you from going with the vine method? I know it can get a little tedious making all those circles, but it is totally worth it. Also gotta have sticky pistons..
It's a little lengthy but it's amazing.
You can get to 50 in about 5-10 minutes.
Basically, sticky pistons with a block on the end and pressure plates will push enderman off platforms down a circular ring that is bridged with 4 spaced "rings" that have vines on them. The vines, in turn reset the fall speed until they fall down into the next level
From a decompiled 1.7.10 a teleportRandomly function is present in in the Enderman defintion.
it is called if the Enderman is:
- wet
- on fire
- in daylight & not fighting
- is fighting & is closer than 16 blocks to their target
(in the last case there is a delay on how often this can be done).
The function generates an X, Y and Z coordinate and places the enderman to that location. The function calls rand.nextDouble() or rand.nextInt(64) to generate a value within ±32 of the original value for each of X,Y and Z. It then calls another function a teleportTo() using these values
(Alternatively if they are fighting and further away from their target, there is a teleport to entity function.)
Therefore, an enderman, without being aggressive, can teleport anywhere within a cube of 64 blocks of itself (subject to having a floor, head room and not ending up in a liquid).
So, to answer the question, no pathing is considered, this teleportation is based on moving directly to a random location.
TL;DR If the room is within 32 blocks of a liquid or daylight and the ceiling is atleast 3 blocks high, an enderman "could" get in randomly without you having any previous contact with it.
Best Answer
Endermen can pick up a limited number of blocks. They can also place these blocks in another location. They cannot, however, pick up any entities, including all items, such as tools or blocks that have already been broken.