The Waters of Life

 is a Fallout 3 quest. It is also an Xbox 360 achievement.

It might be connected to the water filtering facility set up in the Jefferson Memorial.

Dad quotes the following Bible passage in the tutorial: "I am Alpha and Omega, the beginning and the end. I will give unto him that is athirst of the fountain of the water of life freely.", which could simply be foreshadowing, or could mean that he has something to do with this quest.