hi kaustubh , u hav got the rit person to ans this ques becuz this q is for aircrafts , well actually there r the seat toilletes as in or homes and there is a chamber beneath the aircraft/ ship where all the drainage is collectd , there is a network of pipes connected bet toilttes & chamber and the speacial thing is that these r not ordinary pipes but r vaccum pipes , i.e these pipes creates a vaccum due to which suction pressure generates and all the waste get squizzed to the chamber with a very high speed & during the maintanance of the crafts the waste is extracted

thats all buddy
well if u have any other question related to aircraft straight forward ask me ................

Answered by Hemant , an ibibo Citizen, at 11:51 AM on September 12, 2008