The Impluvium (Lat. in - = in -, down -, pluvia = rain) is a pool of water in the Roman atrium, a centrally located room in a residential building of the Italic type.

The Impluvium is a rectangular, shallow catch basin in the middle of the atrium under the compluvium, the roof opening of the atrium. The Impluvium is usually deep about 30 cm and is used to collect the data collected by the surrounding roofs and passed through the compluvium down rainwater, which is collected in a cistern under the Impluvium, from where it of by a Puteal on the edge impluvium can be drawn. Most of the Impluvium is covered with marble.