Holy Water ( quest ) Holy Water is a side quest in " Fallout 3 " that is added to the game with the " Broken Steel " add - on . Quick walkthrough . Detailed walkthrough . This quest will not be offered if Megaton was destroyed during The Power of the Atom . The Lone Wanderer picks up this quest from Scribe Bigsley after asking him what they can do to help . He asks them to investigate the area around Megaton to see why they need more water , after just being sent a week ' s shipment of Aqua Pura . Investigate the vicinity of Megaton . In front of the entrance to Megaton , the player character witnesses a ' cutscene ' of sorts . A non - player character named Rosa gives Micky a bottle of seemingly pure water . He drinks the water and dies . Rosa then approaches the Lone Wanderer , and after a short conversation she reveals that she received the water from a cult in Springvale . Alternatively , the player character can also receive various hints within Megaton , such as a note pinned to the door of the player character ' s Megaton House or a non - player character coming up to the player character and complaining about a cult stealing Megaton ' s water . Any Megaton settler will give the player character a holy water pamphlet if they interact with them . If the player character has very good Karma , then upon entering Megaton , a resident will run up and give them the pamphlet and complain about the cult . Ask about holy water in the Holy Light Monastery . After finding the Holy Light Monastery , the Lone Wanderer encounters Brother Gerard . After giving them some holy water , he refuses to speak to the player character further until they drink it . Once the player character has done that , he reveals that the leader of the church , Mother Curie III , has been " blessing " water so that wastelanders may " bask in Atom ' s Glow . " Gain entrance to the Monastery . There are five options on gaining access to the monastery . One can ask Gerard if they may meet Mother Curie III but they must either be irradiated ( equipping the ghoul mask can fulfill this option ) , pass a Speech check , pick the lock , kill Gerard and loot the key from his corpse or steal it from him via pickpocketing . After gaining entrance , the player character enters the basement of the church by means of a trap door . Mother Curie is giving a sermon to two ghouls as the player character enters . Once she finishes the sermon , she engages the player character in conversation . She tells them that she has been intercepting the Aqua Pura from the Brotherhood caravans ( whom she sees as " angels " ) and turning it into holy water by irradiating it . She does this because she wants to share Atom ' s gift with the people of the Capital Wasteland . This " gift " is ghoulification . Stop the Apostles of the Holy Light . From here on out , one has four options . The player character can convince Curie III to stop via a Speech challenge , a Charisma check or by convincing her that they are the Prophet of Atom ( with a radiation level above 800 rads ) . The Lone Wanderer can irradiate themself using the radiation trap s ( turned on with nearby switches ) , both in the basement and close to the entrance in Springvale . The fourth option is to kill everyone . But know that there is a feral ghoul reaver named Atom ' s Champion and a glowing one named Sun of Atom , both of which will turn hostile . Killing them does not take away Karma . The Power of The Atom . Should the Lone Wanderer destroy Megaton after undertaking the quest , Mother Curie III can be found outside of Megaton as a hostile feral ghoul reaver . Brother Gerard can also be found as a regular friendly ghoul , who will say that he has seen Atom and that he is going to stay at Megaton to wait for Atom ' s guidance . Scribe Bigsley will express shock at Megaton ' s destruction but will still give the player character the money for completing the quest .