Should the deacon purify the sacred vessels after Holy Communion at the altar or at the credence table?
The Pastoral Manual for the diocese provides that the deacon tends to the sacred vessels after Holy Communion as follows: “If not already placed on a side table by those distributing Holy Communion, the deacon of the altar takes the chalice and other vessels to the side table, where he purifies them and arranges them in the usual way. The presider returns to the chair.” (C-54)
The following explanation is a summary of a recent statement published by the Secretariat of Divine Worship with the USCCB in order to clarify similar questions.
The General Instruction of the Roman Missal (GIRM) states that the deacon "prepares the altar" for the Liturgy of the Eucharist; he may also remove the corporal and sacred vessels from the altar after Communion (GIRM 178). The deacon does not purify the sacred vessels at the altar, but at the credence table, perhaps to avoid the appearance of the deacon doing a ministry alone at the altar that is other than preparatory or in assistance to the priest.
Paragraph 163 of the GIRM, when describing the Mass without a deacon, provides that the priest purifies the vessels at the altar or the credence table. Whereas, Paragraph 183, when describing the Mass with a deacon, states that after Holy Communion, the deacon returns to the altar with the priest, collects the fragments, and carries the chalice and other sacred vessels to the credence table, where he purifies them and arranges them, while the priest returns to the chair. It is also permitted to leave vessels on a corporal, suitably covered, on the credence table and to purify them immediately after Mass.
Although the 2004 Instruction Redemptionis Sacramenlum might seem to confuse the rubrics of the GIRM when it states, "Where a Deacon is present, he returns with the priest to the altar and purifies the vessels" (no. 119), this actually coincides with GIRM 183, which similarly says that the priest and deacon return to the altar, and that the deacon purifies the vessels at the credence table. GIRM 183 makes clear what is left unstated by Redemptionis Sacramentum, that purification by the deacon takes place not at the altar, but at the credence table.
If, for expediency, the priest and deacon will both purify the vessels, the priest and deacon may both purify the vessels at the credence table or the altar; or the priest may purify some of the vessels at the altar and the deacon may purify some vessels at the credence table. The deacon should not purify the vessels at the altar alone.