In Jainism, the practice of consuming boiled water instead of simply filtered water is rooted in the principle of ahimsa (non-violence). According to Jain teachings:

• Boiling water is believed to kill the tiny microorganisms (jiva) present in the water, thereby preventing harm to them during consumption. After boiling, the water is allowed to cool and is typically consumed within a limited time (often within 24 hours), as new life forms (microorganisms) can develop if left for longer.
• Filtered water, even though it removes visible impurities, may still contain countless microscopic living beings that are not eliminated by filtration alone. Consuming such water is seen as causing more himsa (violence) because it leads to the ingestion and potential destruction of more jiva.

Therefore, in strict Jain tradition, especially among monks (sadhus and sadhvis) and devout laypersons, boiled water is preferred over filtered water to reduce violence towards microscopic life forms, in line with Jain vows and ethical conduct.