Sva-dhuni - the celestial stream whose touch purifies
Saints at His feet purify by touch like her waters: 'svar-dhuny apah anusevaya' (SB 1.1.15).
River
Ganga
गंगा
Also known as विष्णुपदी · अमर्त्यनदी · स्वर्धुनी · Sva-dhuni (the celestial Ganga)
The Ganga (sva-dhuni, 'the celestial stream') is India's holiest river, rising in the Himalaya (Gaumukh/Gangotri) and meeting the Yamuna at Prayaga; puranic tradition remembers her as the heaven-descended, liberation-granting current. In the processed verses: the sages sheltered at the Lord's feet purify others by their touch, just as the Ganga's waters sanctify those who follow and touch her (SB 1.1.15).
Śrīmad Bhāgavata Mahāpurāṇa 1.1.15 — Sanskrit Wikisource (pinned oldid=110172)
Bank of Parikshit's final vigil
'Prayopavistam gangayam' (SB 1.3.43).
Water purified by the dust of Hari's lotus feet
'apluta hari-padabja-rajah-puta-sarij-jale' (SB 1.8.2) — the Ganga's purity derives from Hari's feet.
Divided into seven streams for the pleasure of the seven sages
'srotobhih saptabhir ya vai svardhuni saptadha vyadhat saptanam pritaye' (SB 1.13.52) — the place is called Saptasrota.
Bears water sacred with the dust of Krishna's feet mingled with tulasi, purifying both worlds
'ya vai lasac-chri-tulasi-vimishra-krishnanghri-renv-abhyadhikambu-netri punati lokan ubhayatra seshan' (SB 1.19.6).