NET
6 Now there were six stone water jars there for Jewish ceremonial washing, each holding twenty or thirty gallons.
Darby
6 Now there were standing there six stone water-vessels, according to the purification of the Jews, holding two or three measures each.
KJV
6 And there were set there six waterpots of stone, after the manner of the purifying of the Jews, containing two or three firkins apiece.