Yes, your understanding aligns with Jain practices during Paryushan Mahaparv, especially in the monsoon period (Chaturmas).

Jain scriptures and traditions prescribe:

• During ekasana (one meal a day) or upvas (fasting), particularly in Chaturmas, boiled water (ukāḷūṁ pāṇī) is to be used.
• Boiled water should ideally be used within one prahar (approximately 3 hours) after boiling.
• This restriction is because, after 3 hours, the possibility of new micro-organisms (jiva) being generated in the water increases, and consuming such water could violate the principle of ahimsa (non-violence).
• Therefore, Jains prepare fresh boiled water every 3 hours and avoid consuming water that is older than one prahar.

References:

• Jain Agamas (Scriptures) — especially in the conduct literature (Ācārāṅga Sūtra, Dasavaikālika Sūtra)
• Jain Upadhyays and Acharyas' pravachans during Paryushan

Summary: Yes, during Paryushan and Chaturmas, Jains are instructed to use once-boiled water within 3 hours (one prahar) to minimize himsa (violence to micro-organisms), especially during ekasana or upvas.