Palestine being a dry country, with few fountains or wells, they used to fill waterpots with water, to prevent the necessity of going to the river, if they were unclean, and to have materials for washing at hand. To prevent any unbeliever from suspecting that a very thin wine was made by the dregs having been left in the vessels, and water poured in upon them, He says expressly, According to the manner of the purifying of the Jews: which shews that those vessels were never used to hold wine.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: Hom. xxii. [al. xxi.] 2.