What is the ruling on purifying water that exceeds two qullahs?

Primary text

Water exceeding two qullahs that is impure without physical change has no means of purification except augmentation. If the water exceeding two qullahs is changed by impurity, it is purified by one of three methods: augmentation to remove the change, letting the change dissipate over time, or bailing out enough water until the remaining volume is two qullahs or more, provided the change is removed. If the remaining volume is less than two qullahs before the change is removed, the change is not considered the effective cause of impurity because it became impure without the change, meaning the impurity does not cease just because the change disappears. This is why large volumes are purified by bailing and long stagnation, while small volumes are not purified simply by the removal of change, as the impurity in the large volume was caused by the change, whereas the impurity in the small volume was caused by direct contact (Mulaqah).