Lord Siva is known as Ganga-dhara, or one who carries the water of the Ganges on his head
"Lord Siva is known as Ganga-dhara, or one who carries the water of the Ganges on his head"
SB Canto 8
Lord Śiva, the best of demigods, who carries on his forehead the emblem of the moon, receives on his head with great devotion the Ganges water emanating from the toe of Viṣṇu. Being aware of religious principles, Bali Mahārāja knew this. Consequently, following in the footsteps of Lord Śiva, he also placed on his head the water that had washed the Lord's lotus feet.
Lord Śiva is known as Gaṅgā-dhara, or one who carries the water of the Ganges on his head. On Lord Śiva's forehead is the emblem of the half-moon, yet to give supreme respect to the Supreme Personality of Godhead, Lord Śiva placed the water of the Ganges above this emblem. This example should be followed by everyone, or at least by every devotee, because Lord Śiva is one of the mahājanas. Similarly, Mahārāja Bali also later became a mahājana. One mahājana follows another mahājana, and by following the paramparā system of mahājana activities one can become advanced in spiritual consciousness. The water of the Ganges is sanctified because it emanates from the toe of Lord Viṣṇu. Bali Mahārāja washed the lotus feet of Vāmanadeva, and the water with which he did so became equal to the Ganges. Bali Mahārāja, who perfectly knew all religious principles, therefore took that water on his head, following in the footsteps of Lord Śiva.