Purity: Insufficient Sidr or Camphor

Practical Laws of Islam as per the teachings of Ayatullah Sistani

Ruling 540:

If the necessary amount of sidr leaves and camphor cannot be found, then based on recommended precaution, the amount to which one has access should be mixed in the water.

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