Suddenly you detect an awful odor emanating from your sink, and you can't figure out why. All plumbing fixtures in the home are connected to the same waste system. Sewer gasses are prevented from backing up into the house by p-traps. A p-trap (the curved drain pipe under your sink) traps water between the fixture and the sewer line -- it's a water door. A p-trap can become filled with so much hair and grease that water is displaced and sewer gas is allowed to escape into the house. Keep p-traps clean and clear using a mild acid or caustic. Vinegar works well if used regularly -- weekly is super. Your house soon will stop smelling like my brother's socks. And that's the On The House tip for today.