Purity: Purification of Wheat, Rice, and Similar Items with Water

Practical Laws of Islam as per the teachings of Ayatullah Sistani

Ruling 158

If the exterior of wheat, rice, and suchlike becomes impure and it is immersed in kurr or flowing water, it becomes pure. It is also possible to purify it with qalīl water. If their interior becomes impure, in the event that kurr or flowing water reaches the interior, it becomes pure.

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