The $5 Plumbing Shortcut Filling Bathrooms with Sewer Gas You step into your bathroom expecting the fresh scent of soap, but instead, you are greeted by a foul, sulfurous stench akin to rotten eggs. You scrub the porcelain, bleach the grout, and run the exhaust fan for hours—yet the sewer gas smell in bathroom sink drains keeps coming back. If this sounds familiar, the issue