Here is the simple Sthānakvāsī (Shvetāmbara) maryādā generally followed for water during Ekāśan:

• What to drink

- Only properly boiled and well‑filtered water (ubālu/ushṇodaka). - No juices, milk, tea, etc. during Ekāśan.

• Day–night rule

- Daytime only. - After local sunset: no water at all (Chauvihār). Resume only after sunrise.

• When to start in the morning

- Begin drinking only after Navkārsī (about 48 minutes after sunrise).

• During Ekāśan

- Strict Ekāśan: water is taken only in the same sitting as the one meal. - Many Sthānakvāsī saṅghs allow minimal sips of boiled water in the daytime (for dryness/medicine), but still avoid any water at night. Follow your local maryādā given by your guru/saṅgh.

• Paryūṣaṇ/saṅyam days (stricter practice)

- Finish the last water before sunset; best is to stop at least one antar‑muhūrta (about 48 minutes) before sunset. - Use only same‑day boiled, properly filtered water.

• Practical care

- Keep boiled water covered in a clean vessel; strain before use. - Take the least number of sips needed to reduce hiṃsā. - If you need water for medicine, take proper pachchakkhān as per your tradition.

For quick references:

• Navkārsī and daytime-only water for Ekāśan
• “Only daytime, no water after sunset” (Chauvihār)
• “When to drink during Ekāśan” (strict vs. relaxed lay practice)
• Paryūṣaṇ: last water timing guidance