My son bought a small one story house. When the washer drains the toilet which is about 30 feet away will expel air (gurgle). The air that gurgles out of the toilet smells like sewer. If 2 to 3 loads of laundry are done, the toilet will not flush for several hours. Any ideas on what to do. Thanks so much for any help. They live in the country so have a septic system...

Is this house on a septic system or city sewer. The washer is trying to vent out the toilet. Have him rod the vent from the roof. Use enough rod to reach peak to basement floor plus 10'.