I have a newly constructed home (1 yr old). When the shower is running or the toilet is flushed (or a combination of the two), there is a gurgling noise from the kitchen sink followed by a strong septic odor. This has recently happened 3-4 times. Nothing like this has happened in the last year of living in the house. The original plan calls for three full baths, but only one is hooked up. The kitchen sink is approximately 30 feet from the bath and has no separate vent pipe. The bath vent stack goes up into the attic but is not extended through the roof. Could this be caused by improper venting? I have a drilled well and our water table is lower than normal. Could this be part of the problem? The odor goes away when water is run in the kitchen sink. How can I correct this?

Your sink is losing its water seal in the trap due to siphoning. Two things catch my eye, the vent must not stop in the attic, it must extend out through the roof. Whoever did this install was ignoring codes so what else did they skip? Follow that vent back down from the attic to insure it is actually venting your system and not part of the unfinished bathrooms. If the vent is intact then it is clogged and is best rodded from the roof with a sewer rodder