police seized 20 kilograms of kava after pulling over an unregistered car .
a 39-year-old man and a 26-year-old woman have been charged .
police found the kava divided into 862 deal bags on sunday .
they also found a small quantity of cannabis and four unrestrained kids .
the pair will appear in katherine magistrates court on monday .
kava is a depressant drug made from the root or stump of the kava shrub .