पादावनेजनपवित्रतया नरेन्द्र ।
स्वर्धुन्यभून्नभसि सा पतती निमार्ष्टि
लोकत्रयं भगवतो विशदेव कीर्ति: ॥ ४ ॥
svardhuny abhūn nabhasi sā patatī nimārṣṭi
loka-trayaṁ bhagavato viśadeva kīrtiḥ
dhātuḥ — of Lord Brahmā; kamaṇḍalu-jalam — water from the kamaṇḍalu; tat — that; urukramasya — of Lord Viṣṇu; pāda-avanejana-pavitratayā — because of washing the lotus feet of Lord Viṣṇu and thus being transcendentally pure; nara-indra — O King; svardhunī — the river named Svardhunī of the celestial world; abhūt — so became; nabhasi — in outer space; sā — that water; patatī — flowing down; nimārṣṭi — purifying; loka-trayam — the three worlds; bhagavataḥ — of the Supreme Personality of Godhead; viśadā — so purified; iva — just like; kīrtiḥ — the fame or the glorious activities.
O King, the water from Lord Brahmā’s kamaṇḍalu washed the lotus feet of Lord Vāmanadeva, who is known as Urukrama, the wonderful actor. Thus that water became so pure that it was transformed into the water of the Ganges, which went flowing down from the sky, purifying the three worlds like the pure fame of the Supreme Personality of Godhead.
Here we understand that the Ganges began when the water from Lord Brahmā’s kamaṇḍalu washed the lotus feet of Lord Vāmanadeva. But in the Fifth Canto it is stated that the Ganges began when Vāmanadeva’s left foot pierced the covering of the universe so that the transcendental water of the Causal Ocean leaked through. And elsewhere it is also stated that Lord Nārāyaṇa appeared as the water of the Ganges. The water of the Ganges, therefore, is a combination of three transcendental waters, and thus the Ganges is able to purify the three worlds. This is the description given by Śrīla Viśvanātha Cakravartī Ṭhākura.