[107.] In accordance with what is laid down by the canons, “one who throws away
the consecrated species or takes them away or keeps them for a sacrilegious purpose, incurs a latae sententiae excommunication reserved to the Apostolic See; a cleric, moreover, may be punished by another penalty, not excluding dismissal from the clerical state”. To be regarded as pertaining to this case is any action that is voluntarily and gravely disrespectful of the sacred species. Anyone, therefore, who acts contrary to these norms, for example casting the sacred species into the sacrarium or in an unworthy place or on the ground, incurs the penalties laid down. Furthermore all will remember that once the distribution of Holy Communion during the celebration of Mass has been completed, the prescriptions of the Roman Missal are to be observed, and in particular, whatever may remain of the Blood of Christ must be entirely and immediately consumed by the Priest or by another minister, according to the norms, while the consecrated hosts that are left are to be consumed by the Priest at the altar or carried to the place for the reservation of the Eucharist.
Coming From the Chatechism
Warning recieving communion unworthily is serious and has penalties.