Dispute about waterline leak. Need legal protection from City of NYC's DEP .

Water line from water main to house leaking on patch of grass near curb. I called DEP. DEP representatives came by and said you got 3 days to fix it or off with your water. I say your contractor did put in a new main in two years ago and it could be inferior workmanship that is causing the leak. Water line markings on my sidewalk are far away from leak and my water pressure is normal. DEP placed the job of digging out the street and replacing over 30 feet of new water line falls on me. with a cost between $6500 to $10000. I say it is city's responsibility. I need protection from the City of New York placing repair cost on me in a short 72 hr time frame and cutting off water.