Mishnayos Terumos Perek 8 Mishnah 5

שיעור המים – that it would be forbidden because of being uncovered.

כדי שתאבד בהןמרה – if here was such a great deal that the poison of the snake would deteriorate [its venom] and would be lost in them, there would be nothing of being uncovered, and they would know how much poison a snake it puts in at one time.

מרה – the poison that the snake puts in is called מרה/bitterness.

בכלים כל שהן – even if they are many, whatever the amount as they are, there is in them on account of be uncovered, when the water is in the utensils.

ובקרקעות עד מ' סאה – there is in them because of being uncovered, more than this, there is none because of uncovering, for the poison is abolished in them. But the Halakha is not according to Rabbi Yosi. But a spring that draws out even a bit, there is nothing in it of uncovering. And uncovered kwaters when they are prohibited to drink them, thusly there are forbidden to give to his cattle to drink and to wash in them his face, hands and feet, and to knead the plaster, and to use them in any manner of usage.