In Jainism there isn’t a single universal fixed time for stopping water after performing Navkarshi Pachkan in the morning. The exact rule depends on which tradition you follow (Digambar or Shwetambar) and on your guru or local community.

• In many followers’ practice, after sunset (or after the day’s Pachkan begins) people refrain from eating, and often also from drinking, until the next morning. In these cases, water intake is stopped once night begins.
• Some traditions (especially among Shwetambar communities or under certain gurus) allow a small amount of water or liquid up to a specified time at night, while still maintaining the vow of Pachkan.
• Digambar practices tend to be more stringent in many places, with stricter limits on consumption after sunset.

Because these timings vary by lineage and guidance, the safest and most accurate answer for you is to check with your local guru or the specific Jain tradition you follow. They can give you the exact cut-off time that applies to your community.