Three years ago we had our house remodeled. We have a well and septic system and our house is near 100 years old. There was a rain drain at the front of the house which was buried because it was no longer going to be used. Two months after the house was completed, we started getting sewer odors in the basement every time we take a shower. In the summer the odor stays outside, but as soon as the ground freezes its back in the basement. How do we fix this? No one can figure it out. There is now a deck over the old rain drain site.