  We show that the homology of ordered configuration spaces of finite trees
with loops is torsion free. We introduce configuration spaces with sinks, which
allow for taking quotients of the base space. Furthermore, we give a concrete
generating set for all homology groups of configuration spaces of trees with
loops and the first homology group of configuration spaces of general finite
graphs. An important technique in the paper is the identification of the
$E^1$-page and differentials of Mayer-Vietoris spectral sequences for
configuration spaces.
