When you ask Walter what needs to be done around here, he asks you to fix broken pipes around Megaton that are making the water pressure at the plant go wonky. When asked why he can't fix them, he says he hasn't got the time and has to maintain the plant. The three leaking pipes require a Repair of 30 to patch.
Location of pipes
The pipes that have to be fixed are leaking water. The locations are as follows:
On the hill where you enter. It is next to the staircase that leads to your Megaton house.
On the hill opposite of where you enter Megaton, near the path that leads to the common house.
When you return, Walter will pay you 200 caps for fixing the pipes and also offer to buyscrap metal from you to maintain the pipes and plant.
Walter's explanation for being unable to fix the repairs is that he can only get away from the plant during the night, when the water isn't running and the leaks aren't visible. However, not only does Walter walk around Megaton during the day sometimes, but all leaks are still flowing during the night.
PCPlayStation 3Xbox 360 When you finish fixing the pipes and have chosen to not sell scrap metal for caps, if you leave and come back it will give you the option to fix them again, but since you already fixed them you can chose the option again to get 400 caps instead of 200.
PCPlayStation 3Xbox 360 Walter has a tendency to vanish and doesn't return after he rewards you and you leave the water treatment plant. This caused by his irregular character movement path which does not prohibit him from walking off high structures and falling to his death.