Answer

For Upwas tomorrow, you may drink water only before the time your Upwas begins.

In the common Jain practice:

• If your Upwas begins from sunrise, then you should stop drinking water before sunrise.
• If you follow the stricter practice of starting from the previous evening, then you should stop after Chovihar/Pachkhan time today.

Explanation

In Jain Dharma, the exact rule depends on the Pachkhan you take:

• Upwas with water allowed before sunrise: Water can be taken before sunrise, then complete fasting begins.
• Chovihar Upwas: No food or water after sunset/Chovihar time.
• Tivihar Upwas: Food is avoided, but boiled water may be allowed during permitted daytime hours, depending on your Pachkhan.

So, the safest answer is: follow the exact Pachkhan given by your guru, elder, or temple practice.

Takeaway

If you are unsure, ask your local Jain elder or guru before taking Pachkhan. Upwas should be done with clarity, devotion, and proper understanding.