For this answer, we look directly to the Constitution on the Sacred Liturgy #279:
“The sacred vessels are purified by the priest, the deacon or an instituted acolyte after Communion or after Mass, insofar as possible at the credence table. The purification of the chalice is done with water alone or with wine and water, which is then drunk by whoever does the purification. The paten is usually wiped clean with the purificator.”
In common English, when you go to purify the chalice, you’ll put a little bit of water in the chalice, swish it around and then drink whatever is left in the chalice.