[Boromir88]

Of The History of the Magic Filter drain and the Untold Story of Balin's reclaim of Moria:

The Magic Filter drain was installed by the Dwarves in some year way back a long time ago in Moria. It was encoded with protecting Runes engraved, for some unbeknownst (ya I made it up) reason by Celebrimbor. The inscription on the filter asked 3 randomized questions to a dwarf only and if he said the correct answer the filter was turned on, if not it imploded. After the Balrog had drove the dwarves out of Moria the Magic Filter went into lockdown and shut itself down. When Balin reclaims Moria for the dwarves, he goes to get the Magic Filter back on and running....unfortunately when he was asked the last question 'What is the average wingspan of a bee?' and he replied, 'Do you mean Bumble or Killer?' The filter was totally confused and imploded blowing a giant crater in the ground of what used to be Moria.