In Jainism, "chovihar" (also spelled "chauvihar") refers to the practice of abstaining from both food and water after sunset (specifically after dusk or, in some traditions, after four prahar—about three hours before sunrise). According to Jain discipline, once chovihar is observed, you should not drink water or consume any food until the next day after sunrise.

So, during chovihar, you can only drink water before sunset (or before your set time for chovihar begins). After that, you must refrain from drinking water until morning, when the vow is completed and you can resume drinking after sunrise and before resuming any other activities.

This practice is observed to maintain purity, discipline, and non-violence (ahimsa), as microbes and living beings in water increase at night.