We recently had to replace a valve under the kitchen sink which goes from the cold water line to the ice maker in the refrigerator. Since this minor work was done, we have had a sewer gas odor in or around the area of the sink and under the cabinet where the valve is located. Previously I've had this odor in rarely used areas such as the drain in the basement floor and I know that adding water to the drain helps, but this one stumps us because it is used frequently. Can you advise?