1. Stagnant water is affected by impurity, with a specific distant-side exception for very extensive ponds.
2. Flowing water is suitable when the impurity has left no relevant effect.
3. Impurity at one edge of an extensive pond does not necessarily reach the other.
4. The death in water of a creature without flowing blood does not itself spoil the water.
5. Death in water of a creature that normally lives there is a distinct exception.