Short answer

• During Paryushan, the last water should be taken before sunset. Best practice is to finish at least one antarmuhurt (about 48 minutes) before sunset. After sunset, do not drink water.

Details (kept simple)

• What to drink: Only boiled and properly filtered water.
• When to drink: Daytime only (from after sunrise until before sunset).
• Stricter observance: Many devotees stop both food and water 48 minutes before sunset (Chauvihar).
• If doing Tivihar: Some allow only water at night on ordinary days, but during Paryushan the encouraged practice is Chauvihar (nothing after sunset).
• Fasting types:

- Upvaas with water: Only boiled, filtered water in daytime; none after sunset. - Nirjal upvaas: No water for the whole day.

• Tradition notes:

- Shwetambar and Digambar lay practice during Paryushan/Dashlakshan both uphold no water after sunset; the 48‑minute caution is widely observed.

• Practical tip: Sunset time changes daily—plan to take your last sips a little earlier to be safe.