Our house is 67 years old. We are on well and septic. We have a water softener, iron filter and a new hot water heater. We have lived here for 2 years. We have an obnoxious sulfur/sewer smell when we use water. The water coming out of the spouts smell normal. When we use water, a gaseous smell comes from the basement. We tried breaking up the concrete in the basement to seal off the floor drain and re-route the floor drain to the sump pump that we installed ourselves. We don't know if the gases are coming back from the septic field or tank. Can you please offer some suggestions? We are at a complete loss. We did not have a bad smell in the Summer, but we are smelling it more now in the winter. Could it be climate related? Please help!