Mishnà su Genesi 38:78

Water which had become so unfit that it could not be drunk by a beast: If it was in a vessel it is invalid, But if it was in the ground it is valid. If there fell into [the water], dye, or gum or sulphate of copper and its color changed, it is invalid. If a person did any work with it or soaked his bread in it, it is invalid. Shimon of Teman says: even if he intended to soak his bread in one water and it fell into another water the water is valid.