Here's a 10-point lowdown on this developing story:
Schools and colleges in Bengaluru have declared a holiday and a number of exams have been rescheduled. Bangalore University has rescheduled Thursday's undergraduate and post-graduate exams to February 6.
Even as buses remain off the roads, Metro services and private taxis like Ola and Uber are running as usual. Traffic is thin as compared to the usual weekday rush.
A spokesperson of Namma Metro said, "If and only if there is a hindrance to the safety of the passengers, we will inform police and stop services."
Emergency services are functioning and the Bruhat Bengaluru Chemists and Druggists' Association said though it supports the bandh, medical shop owners will wear black bands in solidarity.
Around 15,000 police personnel have been deployed across the city. Karnataka Chief Minister Siddaramaiah has urged people to maintain peace.
The BJP calls the bandh "politically motivated" as it was advanced by a few days to coincide with BJP chief Amit Shah's visit to Mysuru to mark the culmination of the statewide Parivartana Rally of BS Yeddyurappa, the BJP's presumptive chief minister in the assembly elections and state BJP chief.
The BJP has accused the ruling Congress of being behind the change of date of the first bandh from the January 27 to the 25th. The Congress has denied the allegation.
Another bandh has been called on February 4 when Prime Minister Modi is scheduled to address a rally in Bengaluru. The BJP has in turn called for bandhs in districts when Congress President, Rahul Gandhi visits the state next month.
The BJP has been at the receiving end of protests on the Mahadayi issue. Farmers earlier had protested outside the party's office in Bengaluru in December claiming that Mr Yeddyurappa had not lived up to his promise to resolve the water sharing issue by December.
Karnataka and Goa are locked in a tussle over the sharing of Mahadayi river waters. The river originates in Karnataka but largely flows through Goa before emptying into the Arabian Sea. The dispute grew over the last two decades after Karnataka's bid to construct dams and canals to divert the waters for parched Gadag, Bagalkot, Dharwad, Belagavi and Gadag districts in north Karnataka.