Purity: Purification by Rainwater and Required Number of Falls

Practical Laws of Islam as per the teachings of Ayatullah Sistani

Ruling 35

If rain falls once on an impure object that does not contain an intrinsic impurity, the area that comes into contact with the rain becomes pure. However, if a person’s body or some clothing has become impure by urine, then based on obligatory precaution, rain must fall on it twice for it to become pure. As for the impure inside of a utensil, rain must fall on it three times for it to become pure based on obligatory precaution. With carpets, clothing, and similar things, wringing out the rainwater is not necessary. Of course, a few drops of rainfall does not suffice; rather, it must be such that it can be commonly said to be raining.

-Ayatullah Sistani, Practical Laws of Islam, Purification (Taharah)