Paryushan (or Pajushan) is one of the most important religious festivals in Jainism. During this period, Jains observe strict rules regarding ahimsa (non-violence), self-restraint, and austerity. The use of "garam pani" (hot/warm water) during Paryushan is a matter of discipline and tradition within Jain practices.

According to Jain traditions:

• During Paryushan, especially among the Shwetambar sect, it is customary to avoid using hot water for bathing or drinking. The primary reason is to minimize violence (himsa) towards microorganisms, which proliferate more in warm water.
• The use of boiled water for drinking is allowed, as it is considered to reduce the number of microorganisms consumed. However, the water should be boiled and cooled before Paryushan each day, and some sects have specific timings for when this water must be used.
• For bathing, cold water is preferred during Paryushan to further minimize himsa.

In summary: During Paryushan, the use of hot water is generally avoided for bathing, and boiled (then cooled) water is used for drinking. Always follow the guidance of your local Jain sangh or spiritual leader for specific practices, as customs can vary between communities and sects.

If you want more detailed information about Paryushan practices or their significance, feel free to ask!