You can pick the lock on the trapdoor behind him. Gerard won’t let you into the church if you aren’t irradiated. You need to get inside to figure this one out. Drink it to realize that it is badly irradiated Aqua Pura. He’ll give you a bottle of holy water and demand that you drink it first. Go into Springvale to find the new church set up in an old house. You can also find out about the new cult through pamphlets from the beggars, a note on your door, or general exploration. She’ll explain that it was supposed to be blessed water from a church in Springvale. You can watch a woman named Rosa accidentally kill a beggar by giving him a bottle of Aqua Pura. Go to Megaton and figure out the source of the water theft.
You obviously won’t have this quest if the town is destroyed. Go to the Jefferson Memorial and talk to Scribe Bigsley about his problems with Megaton. This one is a side quest of the water purification series.
