The Collaborative International Dictionary of English v.0.48:

Seepage \Seep"age\, or Sipage \Sip"age\, n.
   Water that seeped or oozed through a porous soil. [Scot. & U.
   S.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Seepage \Seep"age\, n.
   1. The act or process of seeping; percolation.
      [Webster 1913 Suppl.]

   2. a fluid that seeps out of a container; as, seepage from a
      reservoir.
      [PJC] Seepy

WordNet (r) 3.0 (2006):

seepage
    n 1: the process of seeping [syn: seepage, ooze, oozing]