Enderman will not be angry anymore if they go in water, they will instantly teleport out and they're jaw will go back to normal and they won't be angry at you unless you look at them again.

The best way is to sit on a pool of water then look at the Enderman,it will teleport to you and will repeat it until getting killed.

Actuly, you can kill enderman easly with no armor and stone sword. You just keep hitting its legs and now look in hes head or body, He won't teleport

You could... I don't know... Just keep hitting it?

acctually the best way to kill a enderman is a enchanted diamond sword and you could look at him when you are wering a pumpkin in your head or creative

true endermen dont like water but it only deals little damage, i say use a good knockback sword and knock him really hard, fire aspect also helps with finding him once it teleports away, as for location iknocking it down a hill, but endermen kill easily if you dont have good armor (diamond up) otherwise i wont hit a endermen, the water pouring thing is incase your low on health and the enderman is still annoying you.

so it wont tp away kill it by hiting its legs