Short answer: No. During ekasana you should not take bhasma mixed water.

• What is allowed: plain, boiled water (shuddh/ukāḍu pānī) within the permitted time.
• What is not allowed: any mixed or flavored water—such as bhasma water, lemon water, saline/sugar water, herbal infusions—because it becomes a “mixture” or “aushadhi” rather than plain water.

Tradition notes:

• Shvetāmbara practice: only plain boiled water during the day’s allowed window; mixtures are avoided.
• Digambara practice: eka-bhukti with strict simplicity; tonics or medicinal mixes are not taken as part of the vow.

Health exception: If a doctor prescribes bhasma as medicine and it is genuinely needed, treat it as aushadhi: take it separately with proper pratyākhyān/permission from your guru or as per your sampradāy’s guidance, even if that means relaxing the ekasana for that period. Health takes precedence, but do not count the mixture as part of ekasana.