Initially, the piscina was a reservoir or basin for water, used in ancient Rome in the baths (thermae). In this way, artificial ponds built in the gardens of rich Romans, were also named. During the early Christian period, the piscina was a shallow basin, placed next to the church altar in the presbytery or in the sacristy. It was intended for washing communion vessels. Most often it was made of stone, sometimes it was equipped with a drain. In the Orthodox churches, the piscina is called thalassidion.
romanesque piscina in the church in Saint Vincent sur Yard, 12th century, France, photo Wikimedia Commons
piscina in the St Denys church in Northmoor, 13th century, England, photo Wikimedia Commons
gothic piscina crowned with a trefoil in the St Laurence’s church, Shotteswell, 14th century, England, photo Wikimedia Commons
piscina with a finial in the ogee arch in the Aghaboe Abbey, Ireland, 14th century, photo: A.Borchert, Wikimedia Commons
double piscina in Alte Kapelle, Mülheim Kärlich, 14th century, Germany, photo Wikimedia Commons
gothic piscina in the Notre Dame church in Rosenwiller, 15th century, France, photo: R.Hammann, Wikimedia Commons