Sacraria are used for a variety of purposes, including these:
- To dispose of ashes from objects that have been blessed and then destroyed by fire
- To dispose of the water that has been used to wash the altar linens
- To dispose of water that has been used to dissolve small particles of the host
- To dispose of water that has been used to clean up places where the Precious Blood has spilled
According to the Code of Canon Law,
Canon 1367 A person who throws away the consecrated species or who takes them or retains them for a sacrilegious purpose incurs an automatic (latae sententiae) excommunication reserved to the Apostolic See; if a cleric, he can be punished with another penalty including dismissal from the clerical state.
Pouring the Precious Blood into a sacrarium counts as throwing away the consecrated species, and so it cannot be done.