Answer

In Jain practice, boiled water is generally the proper and accepted choice for reducing harm to living beings in water.

Water with ash is not a standard substitute for boiled water in common Jain Dharma practice.

Explanation

In Jain tradition, water may contain countless subtle living beings. Boiling water is practiced because heat destroys many microorganisms, and after boiling, the water is usually used within a prescribed time limit according to one’s tradition.

Adding ash to water may be used in some local or practical contexts for cleaning or settling impurities, but it is not generally considered equivalent to boiling water from the Jain religious viewpoint.

Spiritual Understanding

The purpose is not only physical cleanliness, but ahimsa—carefulness to avoid harming living beings as much as possible.

So, from a Jain Dharma perspective:

• Boiled water is spiritually preferred and traditionally accepted.
• Water with ash should not replace boiled water unless one is following a specific traditional instruction from a knowledgeable Jain guru.

Takeaway

For Jain practice, choose boiled water. If unsure about details like timing or method, follow the guidance of your Jain sadhu, sadhvi, or learned shravak/shravika.