Forget about what the NYC DEP tells you-they don't want you to get scared. There's a building on Bushwick Ave, the water smell like gas for more than a year but DEP never answered what would be the cause nor the quality of the water. Couple years later, the company who owns gas tank around there announced they did experience petroluem leak which traped in the neighbouring area. I do believe the DEP know what the hack is going on at the time but don't want you to get scared. If all neighbours can smell it, I don't think DEP water test would indicate otherwise.
Last year, NY State found NYC DEP guilty of not announcing the failure of a water processing plant. The letter to me from the State told me that even though the situation is not health threathening but according to the NY State Law, NYC DEP has to announce situation like that to NY residents and report it to the State. As a result, the court fined NYC DEP including fees to pay for the letters mailed to us annoucing the situtation by the State.