Information technology majors Infosys and Wipro are among those suspending operations on Thursday in view of the Karnataka bandh call.
Infosys Development Centre said its Bengaluru offices would remain closed on January 25, while Wipro said it was shutting down for a day as a precautionary measure.
Banks said they would remain open, and their bosses would decide about suspending work if violence is reported.
Called by a network of Kannada organisations, the bandh's objective is to highlight Karnataka's case in the Mahadayi river water dispute with neighbouring Goa.
Politics is in the air, too. The bandh coincides with BJP national president Amit Shah's public rally in Mysuru, causing anxious moments to his party. The ruling Congress is backing the protests.
Deputy commissioners in the districts will decide on whether to allow educational institutions to remain open on Thursday.
The Associated Managements of Primary and Secondary Schools in Karnataka (KAMS) said its member-schools would be closed.
Managements of Independent CBSE School Association (MICSA) has also decided its member-schools will remain closed.
Mansoor A Khan, the general secretary of the association, said the schools might work on a Saturday to compensate for the holiday.
If any pre-university practical exam can't be held on Thursday, it will be held on February 21, an official note said.
Ahead of the second PU exams in March, practical exams are being held from January 22 to February 20.
Visvesvaraya Technological University (VTU) has rescheduled the postgraduate theory examination from Thursday to February 5. Timings remain unchanged.
The police have deployed additional forces in Dharwad and Koppal, major hubs for Mahadayi protesters.
Additional Director General of Police Kamal Pant told DH 170 Karnataka State Reserve Police (KSRP) battalions, 220 City Armed Reserve (CAR) platoons and 63,000 law and order police personnel would be on duty from early morning till late in the evening.
About 120 habitual trouble-makers have been taken into preventive custody across the state, he said.
The Kannada film industry has extended its support to the bandh. All theatres across Karnataka will be closed.
Malls and multiplexes will remain closed across the state till 6 pm.
Government offices in Bengaluru and across the state may see thin attendance as the bandh is backed by the Karnataka Government Employees Association.
Educational institutions have been told to remain closed on Thursday by the deputy commissioner of Bengaluru (Urban) district.
State-run transport corporations said their services would not be disrupted as long as the situation was peaceful.
Namma Metro said its schedule would remain unchanged. Its PRO U A Vasanth Rao said operations would continue as usual.
"Any decision otherwise will be made depending on the situation," he told DH.
"Since petrol bunks come under essential services, it is mandatory to provide services. Any disruption will affect not only members of the public but also ambulance and other emergency services," said Sanaulla Anees, vice president of Karnataka State Federation of Petroleum Dealers.
What's the cause?
Karnataka wants to build barrages across Kalasa and Banduri, two tributaries of Mahadayi, to supply drinking water to 180 villages, besides the twin cities of Hubballi and Dharwad.
15K cops in Bengaluru
Police have made elaborate security arrangements for the bandh. City police commissioner T Suneel Kumar said 15,000 personnel would be on duty across the city.
Speaking at a press conference, he said, "There were violent incidents reported during the Cauvery protest last year, but this time we have taken all precautionary measures."
Apart from 15,000 policemen, 50 battalions of KSRP and 15 CAR platoons will be deployed on Thursday.
Police have also installed CCTV cameras in violence-prone areas and detained habitual offenders, he said.