  We derive a continuity equation to study transport properties in a
$\mathcal{PT}$-symmetric tight-binding chain with gain and loss in symmetric
configurations. This allows us to identify the density fluxes in the system,
and to define a transport coefficient to characterize the efficiency of
transport of each state. These quantities are studied explicitly using
analytical expressions for the eigenvalues and eigenvectors of the system. We
find that in states with broken $\mathcal{PT}$-symmetry, transport is
inefficient, in the sense that either inflow exceeds outflow and density
accumulates within the system, or outflow exceeds inflow, and the system
becomes depleted. We also report the appearance of two subsets of interesting
eigenstates whose eigenvalues are independent on the strength of the coupling
to gain and loss. We call these opaque and transparent states. Opaque states
are decoupled from the contacts and there is no transport; transparent states
exhibit always efficient transport. Interestingly, the appearance of such
eigenstates is connected with the divisors of the length of the system plus one
and the position of the contacts. Thus the number of opaque and transparent
states varies very irregularly.
