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.
Bayangkan. Anak kecil yang berlari pulang ke rumahnya tadi, mungkin memiliki pasokan air bersih yang baik, namun dia akan minum air itu dengan tangannya yang kotor.