Toilet

Drinking from a toilet in Fallout 3 can regenerate health but increases radiation at the same time. Toilets are generally a bad choice when trying to restore health, as the Rads:Health Points Ratio is quite poor. Some Toilets may be trapped, and have wires linking to 35 Microfusion Cells. If you attempt to Drink from these, your screen gets a small shake, and you lose health. To disarm the trap, target the Microfusion Cells and press the activate button. If your Repair skill is high enough, you can disarm it and retrieve the Cells.

However, the toilet in Tenpenny's room in Tenpenny Tower has 0 rads, one of the few (if not the only) 0 rad drinking water in the game.