Here goes a rough calculation of how long it would take to saturate porus materials in the basin of a non-leaking pond.
Pond 1 acre. Porus material in basin 2 acres and dry. The porus material would hold almost the same amount of water as the pond.
So the pond fills, goes down to half full.
Pond fills again, goes down to 3/4.
Pond fills again, goes down to 7/8.
Pond fills again, goes down to 15/16.
Pond 1 acre. Porus material in basin 1/2 acre and dry. Porus material would hold almost 1/4 of the pond.
Pond fills, goes down to .765 full.
Pond fills again, goes down to about .95 full.
A new pond owner who watches his pond drop in days or months to 1/2 or 3/4 full is going to freak out some, and there may not be a problem.
