It is spoken highly of. But what is its significance? What are the benefits? Does it wash away all sins?
SIVAPURANA: VIDYESVARA SAMHITA: Chapter 12 mentions the fruits of bathing in different rivers in different solar months. Here is the relevant verse for bathing in Kaveri in the Tulā month:
The great river Kaveri flowing from the mountain Sahya is very holy and is said to have twenty-seven mouths. It accords all cherished desires. Its banks are the bestowers of heaven and the regions of Brahma and Visnu.
When the Sun and the Jupiter are in Tulā, the devotee shall take bath in the Kaveri, the fruit whereof is the attainment of all cherished desires as stated by Visnu Himself.