tamei tahor ritual purity - The amount of Parah Adumah ashes and water ("mei chatas") required to purify a person

This week's parsha teaches us all about the Parah Adumah and how it can purify a person.

Namely, that in order for a person who was ritually impure via a dead body to become pure, said person would have to have to be sprinkled with mei chatas- ie water with Parah Adumah ashes in it (Rambam Sefer HaMitzvot, Positive Commandment #113).

A couple questions:

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  1) Is there a minimum requirement for the amount of Parah Adumah ashes that must be in the mei chatas?

  
  


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  2) What's the minimum requirement for the amount of water sprinkled that will purify a person?

  
  
  
  
  
  • What's the d'oraisa source for #1 and #2? (ie gezeiras hakasuv, drasha, halacha l'moshe misinai etc)