Yes bathing-at-pilgrimages-like-ganga-yamuna-etc-helps-clear-sins-is-the -Universal Hindu Concept. As the Holiness of sacred River Ganga ji is mentioned in Various Hindu Scriptures.
Even Lord in Shreemad Bhagvat Gita is saying that he himself is Ganga among Rivers.
पवनः पवतामस्मि रामः शस्त्रभृतामहम्।
स्रोतसामस्मि जाह्नवी।। BG 10.31।।
pavanaḥ pavatām asmi rāmaḥ śastra-bhṛtām aham
cāsmi srotasām asmi jāhnavī
10.31 Of the purifiers I am air; among the wielders of weapons I am Rama. Among fishes, too, I am the shark; I am Ganga among rivers.
Mahabharata - Anushasan Parva -Section 27 -P 135 ,136 - is praising Ganga as-
udhishthira said, 'Which countries, which provinces, which retreats,
which mountains, and which rivers, O grandsire, are the foremost in
point of sanctity?'
Brahma said - Even those men who, having committed diverse kinds of
sinful deeds in the first part of their lives, betake themselves in
after years to a residing by the side of Ganga, succeed in attaining
to a very superior end. Hundreds of sacrifices cannot produce that
merit which men of restrained souls are capable of acquiring by
bathing in the sacred waters of Ganga. A person is treated with
respect and worshipped in heaven for as long a period as his bones lie
in the channel of the Ganga.
The entire body of creatures in the three worlds, if served with the
auspicious waters of Ganga,
The Narada Purana The Narada Purana -
The most holy of tirthas is the confluence of the rivers Ganga and
Yamuna. Someone who bathes there attains perpetual good health,
prospers, lives to a ripe old age and is pardoned all his sins. Even
the gods and the sages are fond of the waters at this sacred
In fact, the Ganga is so sacred that even if one just thinks of her,
all pain is relieved and all sins are pardoned. Along the banks of the
Ganga is a remarkable tirtha known as Prayaga. Brahma himself peformed
a yajna there. You can bathe in the waters of all the tirthas if you
so desire. But the punya (store of merit) that you will acquire from
this is only a sixteenth of the punya you will acquire from touching a
few drops of water from the Ganga.
There are some other rivers also in which the Ganga is always present.
Their names are Godavari, Sarasvati, Kalindi, Kaveri, Krishna, Reva,
Vahuda, Tungabhadra, Bhimarathi, Vetravati, Tamraparni and Shatadru.
Conclusion - Shreemad Bhagvat Gita - Mahabharata - Puranas are core universal Hindu scriptures . The Holiness of Ganga and the merits one gets by Bathing in Pilgrimage places from where the Sacred Ganga flows is present in most of the other scriptures also. So Yes this is universal strong Hindu belief.