It is not by accident that there is a great deal of reverence in the Divine Service associated with the celebration of the Lord’s Supper. The Words of our Lord are chanted deliberately and carefully, the body and blood of Christ are adored (e.g., genuflection and the elevation of the elements), and the Sacrament is distributed and received with reverent solemnity.
All of this is fitting, for the Sacrament of the Altar is the true body and blood of our Lord Jesus Christ. This is indicated by the Words of our Lord Himself: “Take, eat; this is my body; take drink, this is my blood.” But what about after the distribution, or even after the Divine Service? What happens to the remaining sacramental elements then? Consider this insightful observation from Pastor Larry Peters:
“Perhaps the most honest expression of what we believe about the Lord’s Supper comes from the way we treat the reliquae (that which remains after the distribution). For what we truly believe is often hidden in the way we handle the things of God when no one is looking, when the Divine Service is over, and we are left alone with our consciences.”
Far from being a trivial matter, a clear confession of the bodily presence of Christ in the Sacrament is at stake in how the reliquae is handled after distribution.
Luther, along with such notable Lutheran theologians as Martin Chemnitz and C.F.W. Walther, urged the consumption the reliquae so as not to “divide the Sacrament by a wicked example, or to handle the sacramental action irreverently.” Luther had a very high regard for the Sacrament, who, according to witnesses, once wept when some of the wine from the chalice was spilled during the celebration of the Lord’s Supper. Commenting on Luther’s Sacramental piety, Hermann Sasse writes, “Perhaps no catholic ever had such reverence for the miracle of the Real Presence as Luther did. No one could think more highly of the consecration, no one could treat the consecrated elements more reverently.” We do well to imitate Luther’s example.
So as to not make it impractical or impossible to consume the reliquae, my parishes do not set out more than we expect to use. Our average communion attendance is considered (which is generally consistent from week to week), along with the possibility of having visitors. If we run out (which has yet to happen), I can always consecrate additional elements.
Following the distribution, any remaining consecrated hosts are consumed. Any crumbs that remain in the paten are cleared into the chalice along with any remaining wine from the individual cups, and this is also then consumed.
While this can be done immediately following the service, it is preferable to consume the reliquae at the altar immediately following distribution. This has the advantage of keeping the entire celebration of the Sacrament in its proper context, the Divine Service. Also, the public consumption of the reliquae leaves no doubt as to what was done with it after the service. If it is consumed in private (which may be necessary in some settings), most of the congregation will not witness this and may have no idea how it was handled.
The practice of pouring the blood of our Lord into the ground after the celebration of the Sacrament, while being a common enough historical practice (and even appears in Reed’s rubrics in The Lutheran Liturgy), is without biblical warrant. While this practice is commendable in that it makes an effort to treat the blood of our Lord with reverence (as it is certainly preferable to pouring it down the sink or toilet), it is nevertheless a departure from “take, drink.” As to storing consecrated hosts for future use, this is also common (and endorsed by the likes of Walther and Reed), but it is better still to keep consecration, distribution, and reception together, as indicated by the following citation of Deyling by Walther:
“The elements consecrated by the pastor can neither be preserved nor sent to those who are absent, which was an evil custom of some in the ancient church. For the sacramental action, which consists of consecration, distribution, and reception, must be completely uninterrupted,” (Pastoral Theology, 144).
Whether or not something may be done is a different question than whether or not it should be done. Where consecration, distribution, and reception are kept together, there is no room for doubt or confusion. Additionally, as a public act, consuming the reliquae at the altar affords us another opportunity to teach what we believe, teach, and confess about the Lord’s Supper. Our communion practice ought to display our reverence for the body and blood of Christ when the elements are consecrated, when they are distributed, and after distribution. Our Lord Jesus Christ invites us to His table, saying, “Take, eat; take, drink;” and it is our great privilege to do so.
 For the Luther quote & the teachings of Chemnitz and Walther in this regard, see the excellent presentation “To Mix, or Not to Mix: The Sacramental Character of the Reliquiae” by Rev. Paul L. Beisel to the 2007 Iowa District East Fall Pastor’s conference at http://www.gloriachristi.org/sitebuildercontent/sitebuilderfiles/tomixornottomix.pdf
 Cited in Beisel, 7.
 Rev. David Jay Webber has complied a number of helpful quotations pertaining to the Sacrament, including Luther’s admonition that the remains of the Sacrament should be consumed with the rest of the communicants. They can be found at http://www.angelfire.com/ny4/djw/lutherantheology.consecration.html.
 Consider also the following quotation from Chemnitz, Kirchner, & Selneccer: “The Christian Concord goes no farther than the correct use instituted by Christ. And it does not say anywhere either that [the Sacrament] is to be placed in a pyx and locked up in the eucharistic tabernacle and, as previously stated, it speaks only about the use instituted by Christ Himself,” (Apologia oder Verantwortung des christlichen concordien Buchs, 157-158, as quoted by Murray; Logia 9 No 3, 2000:15).