<P> The sacristy is usually located inside the church, but in some cases it is an annex or separate building (as in some monasteries). In most older churches, a sacristy is near a side altar, or more usually behind or on a side of the main altar . </P> <P> In newer churches the sacristy is often in another location, such as near the entrances to the church . Some churches have more than one sacristy, each of which will have a specific function . Often additional sacristies are used for maintaining the church and its items--such as candles and other materials . </P> <P> The sacristy is also where the priest and attendants vest and prepare before the service . They will return there at the end of the service to remove their vestments and put away any of the vessels used during the service . The hangings and altar linens are stored there as well . The Parish registers may be kept in the sacristy and are administered by the parish clerk . </P> <P> Sacristies usually contain a special wash basin, called a piscina, the drain of which is properly called a "sacrarium" in which the drain flows directly into the ground to prevent sacred items such as used baptismal water from being washed into the sewers or septic tanks . The piscina is used to wash linens used during the celebration of the Mass and purificators used during Holy Communion . The cruets, chalice, ciborium, paten, altar linens and sometimes the Holy Oils are kept inside the sacristy . Sacristies are usually off limits to the general public . The word "sacristy" derives from the Latin sacristia, sometimes spelled sacrastia, which is in turn derived from sacrista ("sexton, sacristan"), from sacra ("holy"). </P>

Where does the priest get ready for mass