Terumos 8:4

If it was discovered that terumah wine had been left uncovered, it must be spilled out (for safety reasons, without concerns of wasting terumah); all the more so, chullin wine must be disposed of in such a case. Water, wine and milk must all be disposed of if they were left uncovered but other liquids remain permitted. The amount of time uncovered to prohibit a liquid is the amount of time that it would take a lizard to come from a place close by and drink from it.

Terumos 8:5

The amount of water forbidden by being uncovered is until a volume that would adequately dilute a snake’s venom. Rabbi Yosi says any amount in vessels is prohibited, and up to forty seah in the ground (around 140 gallons).