Why do Hindus immerse ashes of the dead in holy rivers like the Ganga?
The remnant of the dead body after burning is left behind in the form of ashes. Hindus respectfully call these ashes phool - literally flowers - to express devotion and respect for the departed soul When children are symbolically referred to as 'fruit', it is appropriate to refer to the ashes of forefathers as 'flowers'.
It is customary to gather the ashes on the fourth day after death. They are then immersed in sacred rivers like the Ganga. If it is not possible to immerse them immediately, they are kept in a locker in the crematorium and immersed as soon as possible.
In the Shankhsmriti, the consigning of ashes to the Ganga is explained:
As long as the ashes of the deceased person remain in the Ganga, the person continues to enjoy happiness in worthy places for thousands of years.