Tractate Makhshirin - Chapter 4 - Mishnah 1 מכשירין פרק ד׳ משנה א׳

If one bent down to drink, the water which came up on his mouth or on his moustache comes under the law of ‘if water be put’; But [what came up] on his nose or on his head or on his beard does not come under the law of ‘if water be put’. If one drew water with a jar, the water which came up on its outside, or on the rope which was wound round its neck, or on the rope which was needed for its use, comes under the law of ‘if water be put’. How much rope is needed for its use? Rabbi Shimon ben Eleazar says: a handbreadth. If he put the jar under the rain-pipe, it does not come under the law of ‘if water be put’.