We installed a new mounded septic system in the back yard of our church parsonage this past June. Since then, significant rainfall causes odor to back up into the house. There are two bathrooms in the house, one in the basement, and one on the second floor. The problem seems to originate when the second floor bathroom gets used.
Is this a design problem, or something that will improve with time as the system matures?
Should the designing engineer be called in? How should it be tested?
Scout33, the sewer gas odors eminating into the second floor bathroom are probably not coming from the mounded leach field in the back yard.
The sewer gas odors are created by microbial digestion of the organic matter in the septic tank, and by microbial digestion of the scum and other residue in the plumbing system in the parsonage. The odorous gasses rise through the vent system in the house, and are discharged into the air above the roof. If there is a leak in the vent system, or if a trap in the plumbing system loses the water seal, then the gasses will enter the house. I recommend that you call a Licensed Master Plumber to investigate the origin of the odors. JWA