Matsya Purana — Rite and Layout for Consecrating Ponds
प्रावृट्काले स्थिते तोये ह्य् अग्निष्टोमफलं स्मृतम् शरत्काले स्थितं यत्स्यात् तदुक्तफलदायकम् वाजपेयातिरात्राभ्यां हेमन्ते शिशिरे स्थितम् //
prāvṛṭkāle sthite toye hy agniṣṭomaphalaṃ smṛtam śaratkāle sthitaṃ yatsyāt taduktaphaladāyakam vājapeyātirātrābhyāṃ hemante śiśire sthitam //
Standing in water during the rainy season (prāvṛṭ) is said to yield the fruit of the Agniṣṭoma sacrifice. If done in autumn (śarat), it grants the fruit previously stated. And when performed in hemanta and śiśira (early and late winter), it yields the merit of the Vājapeya and Atirātra sacrifices.
This verse is not about pralaya; it teaches ritual discipline (tapas) whose merit is equated with major Vedic sacrifices depending on the season.
It offers a practicable austerity—standing in water seasonally—by which householders (and kings) can gain the merit of costly śrauta yajñas, aligning personal discipline with dharma when full-scale sacrifices are difficult.
The significance is ritual, not architectural: a seasonal water-austerity is presented as a substitute/parallel for Agniṣṭoma, Vājapeya, and Atirātra, emphasizing correct timing (ṛtu) as a key factor in religious efficacy.