In a church near the altar, normally in the sacristy, one will find a basin that is used to clean sacred vessels after Mass. It is also used as the place in which to dispose of any materials that were used in the sacraments, including disposing of the water that was used for the liturgical ablutions.
The purpose of having a special basin is to ensure that the water and other materials used during Mass, for the consecration of the bread and wine and which are therefore linked in some way to the Blessed Sacrament, are returned directly to the earth as a sign of respect and not by just dumping them down into a normal everyday household drain.
The basin is known as piscine and the actual drain, in the piscine, is known as the sacrarium. Anglicans usually refer to the basin, calling it a piscina. Roman Catholics usually refer to the drain, and by extension, the basin, calling it a sacrarium.
The sacrarium can be found in Roman Catholic, Anglican, and Lutheran churches, and a similar vessel is used in Eastern Orthodox churches. At least it should still be found in all Roman Catholic churches, in my opinion.
With all the emphasis we place on love and adoration of the Blessed Sacrament, I would really like to believe that everything used in connection with the Blessed Sacrament will also portray our profound belief in the Real Presence, body, soul and divinity, of our Lord Jesus, in the consecrated bread and wine.