Matsya Purana — Cosmic Architecture of Sun–Moon and the ‘Houses of the Gods’
तासां चतुःशतं नाड्यो वर्षन्ते चित्रमूर्तयः चन्दनाश्चैव मेध्याश्च केतनाश् चेतनास्तथा //
tāsāṃ catuḥśataṃ nāḍyo varṣante citramūrtayaḥ candanāścaiva medhyāśca ketanāś cetanāstathā //
Of these, four hundred channels (nāḍīs) pour forth, of wondrous forms: some are fragrant like sandalwood, some are purifying and fit for rites, and others are also named Ketanā and Cetanā.
This verse is not about Pralaya; it classifies sacred ‘nāḍīs’ (channels) and their qualities, emphasizing auspicious, purifying waters used in religious contexts.
It supports dharmic practice by identifying waters considered medhya (ritually pure), guiding householders and rulers in selecting proper water sources for rites, consecrations, and public religious works.
Ritually, it highlights ‘medhya’ waters suitable for ceremonies; in Vastu/temple practice, it implies that the presence and quality of water-channels near a site can be auspicious and relevant for consecration and daily worship.