The toilets work on a Vacuum system so when there is no power on the ship the toilet vacuum system stops.
The toilet bowl won't open as there is no vacuum to whoosh it away so any No.1's & No.2's you do just sit in the bowl hence the cabins & toilets are full.
When you have 100's of people having a poo it doesn't take long for it to get out of hand.
Built in 1999 the Carnival Triumph is quite old - if you go Cruising stick with modern Tonnage which have 2 completely seperate Enginerooms which each can fully operate the ship if there is a problem.
Quote from the BBC -Carnival has cancelled more than a dozen planned voyages aboard the Triumph, while acknowledging that the crippled ship had other mechanical problems in the weeks before the fire.
You get what you pay for on Cruise's - cheap = old cheap ships
Saying that the Concordia was new & she went bump - strange run by same Company !