In Jainism, "Chauvihar" refers to the practice of not consuming any food or water after sunset, and specifically, refraining from eating and drinking after a designated time in the evening. The exact Chauvihar time varies daily, depending on the local sunset time.

For Mumbai, Chauvihar time generally begins about 48 minutes after sunset (which is the time of "Porshi" or nightfall as per Jain tradition). The sunset time in Mumbai today can be checked using a reliable local calendar, Jain Panchang, or trusted Jain apps/websites such as Jain Calendar or Tithi.com.

To find the precise Chauvihar time for today in Mumbai:

1. Find today’s sunset time for Mumbai.
2. Add about 48 minutes to the sunset time.
3. The time immediately after that is when Chauvihar should begin.

For the most accurate and updated Chauvihar timing, please refer to your local Jain Panchang, Jain temple notice board, or Jain community app specific to Mumbai, as this is the traditional and community-accepted source.