There are two containers, generally made of transparent glass, but also of other materials, of various sizes, with lids and placed on a plate or tray. The cruet set: one is for the wine and the other is for the water; it can be taken to the Altar during the offertory. 1*At the Altar the priest pour wine into the Chalice, and a few drops of water is also put into the chalice. (The Order of Mass 24)

The water in the cruet is also used after communion to purify the chalice, paten or ciborium.