The decision was taken at a Cabinet meeting presided over by Chief Minister Sheila Dikshit.
The revenue department has been tasked to conduct the survey and prepare a list of all such structures.
Officials said the city government decided to carry out the survey following a Supreme Court directive.
"This will give us clear picture on the total number of such structures. Revenue department has been asked to coordinate with all the other departments and file a report," they said.
The government is also likely to fix responsibilities on officials as they are often found to turn a blind eye to