Think about it. That little boy who's running back into his house, he may have a nice, clean fresh water supply, but he's got dirty hands that he's going to contaminate his water supply with.
Denken Sie darüber nach. Dieser kleine Junge, der zurück in sein Haus rennt, hat vielleicht angenehmes, sauberes Trinkwasser, aber seine schmutzigen Hände  kontaminieren sein Trinkwasser.