Where should we immerse the ashes — does it have to be the Gaṅgā?

the Gaṅgā is most cherished, but any sacred river, confluence or the sea is fully valid.

Immersing the asthi in the Gaṅgā — at Haridvāra, Prayāga or Kāśī — is the most loved choice, because Gaṅgā is seen as the river that carries souls towards liberation. But tradition also honours many other waters: the Narmadā, Godāvarī, Kāverī, Kṛṣṇā, the Triveṇī saṅgam, Nāsik's Rāmakuṇḍa, Rāmeśvaram's sea, and local holy rivers your family has always used.

What is commonly done: a priest at the ghāṭ performs a short pūjā and piṇḍa offering, then the kartā lets the ashes go into flowing water while chanting God's name. Many pilgrimage priests (paṇḍās) also record the death in the family's genealogy register.

If you cannot travel soon, you may immerse in a nearby river or the sea now, or keep the ashes respectfully until a planned visit. Please also avoid plastic, and put flowers and the earthen pot in the water only where this is allowed.

Source: Garuḍa Purāṇa; tīrtha tradition · Pilgrimage priests keep family genealogy records

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