I bought a new construction home last November that was on the market for over two years. When you first run water in the morning in both the upstairs and downstairs bathroom sinks a horrible sewer smell comes out of the drain but eventually goes away. The plumber was not able to determine the cause. He said he checked the traps under the sink, the vent on the roof and also ran a camera down the sink but couldn't find anything. Any other suggestions. Not a pleasant odor when trying to brush your teeth.

Try this. Tonight, before bedtime pour a 1/2 gallon of bleach down both drains and let it set overnight. Next morning take a pan of boiling water and flush out the drains, Smell better now? Let me know. Tom

IT WORKED! After 2 months, still no odor. Thanks!!