The Church's guidelines in this matter highlight the reality of Jesus' presence in the Eucharist.
On occasion during the distribution of Holy Communion at Mass, a host will fall to the ground or the precious blood will be accidentally spilled. Whenever this happens, the priest, deacon or extraordinary minister of Holy Communion is instructed to take care that the body and blood of Jesus is treated with the great reverence that it is due.
According to the General Instruction of the Roman Missal, “If a host or any particle should fall, it is to be picked up reverently; and if any of the Precious Blood is spilled, the area where the spill occurred should be washed with water, and this water should then be poured into the sacrarium in the sacristy” (GIRM, 280). The “sacrarium” is a special basin in the room next to the sanctuary that has a drain directly into the ground. In this way the natural elements are returned to the earth in a dignified manner.
This procedure is taken one step further in an older instruction from a document entitled De Defectibus, where it states, “If the consecrated host, or any particle of it, falls on the ground, it should be reverently taken up, and the place where it fell washed and slightly scraped, the dot or scraping being put into the sacrarium.”
The host that falls is normally consumed, though sometimes it is saved in the sacristy and put in a dish of water and once the host has dissolved enough, the water is poured down the sacrarium.
It is often not possible to complete all these steps during the celebration of Mass, so usually a priest will place a white cloth over the spot so that it can be properly cleaned up after Mass.
The reason why the Church goes at such great lengths to care for the proper handling of the Sacred Species at Mass is because the Church firmly believes in the words of Jesus, “this is my body, this is my blood.” As the Catechism of the Catholic Church explains, “By the consecration of the bread and wine there takes place a change of the whole substance of the bread into the substance of the body of Christ our Lord and of the whole substance of the wine into the substance of his blood” (CCC 1376).
With this reality in mind, it is not simply bread and wine that fall to the ground, but the body and blood of our Savior. This belief informs everything the Church does in connection to the Eucharist, recognizing that it is God himself who is present and our response to such accidents should be formed by our personal love of him who created us.
This is not a scrupulous activity, but one filed with tenderness, saddened that our Beloved has fallen to the ground. It is our duty to pick him back up and treat his body and blood with all due reverence.