To complete your civil enginnering in a reputed NIT colleges and in any top colleges in india so you have to definetly get qualified in the JEE mains but there are state level colleges and some of the universities in which in order to complete civil enginnering you need not to qualify the JEE mains exam they have seperate entrances and state level entrance exama and some local colleges there is no need of entrances too so that you can complete ypur civil engineering but try to complete your civil engineering in a reputed college so that you can definetly get succeded in life and that would give a lot of value to you 

JEE Mains is compulsory for Civil Engineering or not depends upon the college you want admission in. 

If a student wants to take admission in NITs (National Institute of Technology) ,IIITs (Indian Institute of Information Technology) then he/she has to clear JEE Mains and score high rank in the entrance exam. 

If a student wants to take admission in private institutes then he/she must give the entrance exam conducted by that respective institute. (Only few private institutes in India give admission in engineering on the basis of JEE Marks)

If a student wants to take admission in IIT (Indian Institute of Technology) then he/she must qualify JEE Mains and achieve high rank in JEE Advance. 

If a student wants to take admission in State Government Colleges then he/she must give entrance exam conducted by that particular State. 

If you still have any queries feel free to ask in the comment section down below.