  A leak is a vertex that is not allowed to perform a force during the zero
forcing process.
  Leaky forcing was recently introduced as a new variation of zero forcing in
order to analyze how leaks in a network disrupt the zero forcing process. The
$\ell$-leaky forcing number of a graph is the size of the smallest zero forcing
set that can force a graph despite $\ell$ leaks. A graph $G$ is
$\ell$-resilient if its zero forcing number is the same as its $\ell$-leaky
forcing number. In this paper, we analyze $\ell$-leaky forcing and show that if
an $(\ell-1)$-leaky forcing set $B$ is robust enough, then $B$ is an
$\ell$-leaky forcing set. This provides the framework for characterizing
$\ell$-leaky forcing sets. Furthermore, we consider structural implications of
$\ell$-resilient graphs. We apply these results to bound the $\ell$-leaky
forcing number of several graph families including trees, supertriangles, and
grid graphs. In particular, we resolve a question posed by Dillman and Kenter
concerning the upper bound on the $1$-leaky forcing number of grid graphs.
