I am a bit paranoid about leaks, particularly as our C&C sits on the carpet in my girls playroom! In the corners that the boys like to spend most time in I put puppy pads in first and then on top of this I line the entire cage with a good layer of newspaper (the puppy pads last for ages because they rarely get wet as the paper is changed daily or at least every other day). On top of that I put some old towels, then fleece and just because I spoil the boys I also have some vetbed under their little hidey houses! Overkill or what! ;D ;D
The fleece is just a fleece blanket I got for next to nothing from Ikea, wash it in washing powder but no softener about three times before using and that way it draws all the wetness away from the pigs (in the same way as vetbed does). The towels and paper underneath soak up any moisture. You could probably get away without the towels if you plan on changing the paper daily - as I said I am just paranoid about leaks!
Hope that helps.