In this glorious hadith, Muhammad, an expert hydrologist, explains that nothing makes water impure, that it’s safe and ideal to pour even the filthiest water over your face for ablution (wudu). There can be garbage in there. Menstrual rags. Rotting corpses. It doesn’t matter.
In Islam, Allah rejects your prayer unless you are ritually pure (tahir). If you urinate, defecate, fart, touch your penis, eat camel meat, sleep—all of that makes you impure (najis). To purify yourself and have your prayers accepted by Allah, you must perform wudu, which is to pour water over various parts of your body, also rinsing your mouth and nose.
Now just think of the preposterousness of this for a moment. You just had a nice dinner consisting of well-done, properly cooked camel meat. But per Islamic law, this has made you impure. And so to correct this, you take water steeped with a rotting dog corpse, with trillions of hazardous bacteria, and pour it on your face and, not only that, YOU RINSE YOUR MOUTH AND NOSE WITH IT.
So based on Muhammad’s wisdom, the residents of Fukushima, Japan can confidently rinse their mouths with local well water. And even if there were a radiation risk, would not the greater risk be that Allah rejects their prayers?