- "Sacrarium" redirects here. For the sacrarium of ancient Roman religion, see Sacellum.
A piscina is a shallow basin placed near the altar of a church, or else in the vestry or sacristy, used for washing the communion vessels. The sacrarium is the drain itself. Anglicans usually refer to the basin, calling it a piscina. Roman Catholics usually refer to the drain, and by extension, the basin, as the sacrarium. They are often made of stone and fitted with a drain, and are in some cases used to dispose of materials used in the sacraments and water from liturgical ablutions. They are found in Roman Catholic, Anglican, and Lutheran churches, and a similar vessel is used in Eastern Orthodox churches.
The piscina is a Latin word originally applied to a fish-pond, and later used for natural or artificial pools for bathing, and also for a water tank or reservoir. In ecclesiastical usage it was applied to the basin used for ablutions and sometimes other sacraments.
They were originally named for the baptismal font. Piscinae seem at first to have been mere cups or small basins, supported on perforated stems, placed close to the wall, and afterwards to have been recessed therein and covered with niche heads, which often contained shelves to serve as ambries. They were rare in England until the 13th century, after which there is scarcely an altar without one. They frequently take the form of a double niche, with a shaft between the arched heads, which are often filled with elaborate tracing.
The purpose of the piscina or sacrarium is to dispose of water used sacramentally, by returning these particles directly to the earth. For this reason, it is connected by a pipe directly to the ground; otherwise presumably a basin was used.
Ordinarily the piscina is used in cleaning the sacred vessels after the Mass (see Ablution in Christianity). Cleaning the vessels in this basin ensures that any remaining consecrated particles are returned directly to the Earth. If the consecrated Hosts become unusable, the priest disposes of the hosts by placing them in the sacrarium. This is accomplished by breaking the hosts up into small pieces and washing them into the basin — which returns the consecrated hosts to the ground.
At times the piscina has been used for disposal of other items, such as old baptismal water, holy oils, and leftover ashes from Ash Wednesday. A common myth is that consecrated wine was also poured down the piscina. Actually, the rubrics stated that clearly any consecrated Blood of Christ that that is left over after communion is consumed either by the priest or by those who assist in the distribution of the Eucharist (the extraordinary ministers of Holy Communion), there has never been a time when the Precious Blood was officially poured down the drain. What caused this confusion is that in countries with plenty of cheap wine, if there was any unconsecrated wine left in a cruet, that wine was washed down the piscina.
In the Roman Catholic Church, pouring the consecrated wine, the Blood of Christ, or the Host down a sacrarium is never permitted. 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.” This applies to 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.
Eastern Christianity 
In the Eastern Orthodox and Eastern Catholic Churches the piscina is called a thalassidion, and is located in the diaconicon (sacristy). The thalassidion is a sink that drains into an honorable place in the ground where liquids such as the water used to wash holy things may be poured, and where the clergy may wash their hands before serving the Divine Liturgy. In Orthodoxy the Sacred Mysteries (consecrated elements) are never poured into the thalassidion, but must always be consumed by a deacon or priest.
In some ancient churches, the thalassidion was placed under the Holy Table (altar), though now it is almost always located in the diaconicon. At one time, before a monk or nun was tonsured, their religious habit would be placed on the thalassidion; now, since the separation of the thalassidion from the Holy Table, the habit is placed on the Holy Table. When a monk or nun is tonsured, if the hair must be disposed of, it is thrown into the thalassidion.
See also 
- "Piscina". Catholic Encyclopedia. New York: Robert Appleton Company. 1913.
- Redemptionis Sacramentum 107
- Redemptionis Sacramentum 194
- Cf. Pontifical Council for the Interpretation of Legislative Texts, Response to dubium, 3 July 1999: AAS 91 (1999) p. 918.
- Robinson, Nalbro' Frazier (1911), Monasticism in the Orthodox Churches, AMS Press, ISBN 978-0-404-05375-8
|Wikimedia Commons has media related to: Piscinas (architecture)|
- East Hoathly Parish Church building and contents, with a photograph and description of an 11th or 12th-century piscina