We just returned home after being away for 6 months. Friends frequently came over and flushed toilets. As soon as we ran the washing machine we got a really bad sewer smell. Have been running taps and flushing toilets. Is this enough?

Your traps under sinks and tubs likely dried up and allowed sewer gas into the home. Run water at every fixture and ventilate, you should be good.

We just returned home after being away for 6 months. Friends frequently came over and flushed toilets. As soon as we ran the washing machine we got a really bad sewer smell. Have been running taps and flushing toilets. Is this enough?
Follow Bobs advice and run water in all traps including the floor drain in the basement. Good luck, Tom