Hi, I had an new septic tank and drain field installed (to replace a failed system) the 1st week in June. About 3 weeks ago I occaisionally caught whiffs of sewer smell outside. It was always in the morning and around the area where the new tank was put in. as it's getting colder, I'm noticing it more frequently. Yonight it's in the upper 30"s and I just opened my back door and the outside air odor is quite strong. I never had this experience with the old system. BBefore call the contractor, any common reason why? Any info will be greatly appreciated. Thanks.

Eamille,
This link will explain what causes the smell, why it's so bad in colder weather and what to do about it. Cold Weather & Wet Weather Septic Tank Odors Sewer Odors - how to diagnose, find, and cure wet or cold weather-related sewer gas odors or smells - Diagnosing and Repairing Septic Odors Sewer Odors Sewage Odors
Good luck, Tom