Definition of "seepage"

seepage

noun
countable and uncountable, plural seepages
1. The process by which something, especially a liquid, leaks through a porous substance; the process of seeping. (Also used figuratively: the process of diffusing.)
  Quotations
  […] while they all admit that the most serious losses occur by seepage of gas from, and oil into, the combustion-chamber and that this seepage is […]
  1922, S.A.E. Journal, page 262
  In the case of the Rio Blanco experiment, it is the seepage of gas which is considered to be the "worst possible situation" that might occur.
  1972, Rio Blanco Gas Stimulation Project: Environmental Impact Statement, page 42
  Despite some seepage of customs from north of the border, the Day of the Dead is not [widespread in the US].
  2014, Joe Nickell, Adventures in Paranormal Investigation, University Press of Kentucky
2. Water that has seeped or oozed through a porous soil.