Can a builder build a swimming pool in karab land

Dear sir , This is venkatesh from Bengaluru , we recently shifted to an apartment , on sarjapur road building have 1 gunta B karab land , so builder saying that land belongs to owner of land he trying to build a swimming pool on B karab land , on survey sketch its clearly shows that road is passing on karab land , i would like now that can builder build a swimming pool how it can effect to the flat owners, thank you