Why Plumbing Drains Smell And What You Can Do About It

Nobody wants to have a home that smells like sewage or rotting food. If you keep your house clean but discover that the putrid smells are coming from at least one of the drains, it can be vexing. There are several reasons why plumbing drains smell and solving the problem can be easy—or require the services of a professional plumber. Below are some of the reasons why your plumbing drain smells.

Dried Out P-trap

The p-trap is the curved pipe set under a drain. The goal of the curved pipe is to trap water creating a barrier between the sewer system and your home. This blocks the sewer gas; in case it flows the wrong way up the pipe. If your plumbing drain is only used on occasions, the water in the p-trap can dry up allowing the sewer gasses to pass through and will make your drain smell. You should let water flow down the drain for one minute to trap some water in the p-trap.

Clogged Vents

Your plumbing system has vents inside to prevent pressure build up between the drains and sewer because of sewer gasses. These vents let the gas escape upwards through the roof of your property. If the vents become clogged for any reason, it is going to push the gas towards the easiest escape path it can discover, which will push it upward through the water in the p-trap of a sink, or a toilet causing the drain to smell. In this case you will hear air gurgling in the water coming from the drains. Professional plumbers can help locate where the vents are blocked and unclog them.

Broken Sewer Line

A broken sewer line can be the most pressing issue since a damaged sewer line will ultimately cause sewage and sewer gas to backup into your property. If more than one drain is emanating putrid odors, then it’s most likely a sewer line problem that is causing the drain to smell. You should call a professional plumber immediately. Repairing or changing a broken sewer line is a highly technical job, and should not be attempted as a DIY project.

If the drain smell is not coming from sewer gasses, it may just be some type of buildup on the inside of the drain pipes. Follow the steps below to help disinfect and clean the pipes.

If the smell is specifically coming from the garbage disposal see our article “Garbage Disposal Maintenance Tips: Keep It Clean, Running, And Odor Free“.

What You Can Do About a Smelly Drain:

  • Pour some white vinegar down the drain.
  • Pour in a quarter cup of baking soda.
  • Let this mixture stand for about 2 hours.
  • After the wait, pour in about a gallon of hot water. Water that is too hot may affect PVC drain pipes.
  • Wait for 15 minutes, and pour some cold water down the drain for another 5 minutes; to rinse off the vinegar. Please don’t skip this step it is very crucial that the vinegar is washed off.

Don’t mix the bleach and the vinegar, or you’ll create a toxic chlorine gas.

  • Follow this by pouring a half cup of chlorine bleach and letting it sit for 2 hours.
  • Rinse off with a gallon of hot water.
  • Turn on the tap and let the cold water run for 2 minutes. By now the p-trap will have trapped enough water.