Drains carry smelly waste and gases, although the smell doesn't normally foul up the house. Therefore, you know something is wrong with your plumbing or drainage system if your drains are causing your house to smell. Below are some of the ways drain odor can foul up your house.

Waste Leaks or Backups

Drains carry waste that should flow out of the house for safe treatment at either the septic drain field or municipal waste treatment center. Your house will be smelly if the waste leaks or backs up into the house. For example, septic waste can back up into the house if you don't pump the tank frequently enough and the tank overflows.

Mold and Mildew

Mold and mildew have a distinctive smell that some people describe as decay. Mold and mildew thrive in moist areas. The presence of organic debris also encourages mold growth. Your drains can make your house smell if the drains leak and trigger mold growth. For example, a leaking toilet can trigger mold growth in the bathroom.

Slow or Blockade Drains

Drains carry organic waste and bacteria. The bacteria feed on and break down the waste into different compounds — the decomposition process. The decomposition process releases gases, but you normally don't sense the smell since the decomposition occurs away from the house.

The situation changes if something blocks your drainage pipes and waste doesn't flow as usual. Tree roots, solid waste, and FOG (fats, oils, and grease) can block waste flow. The blockage allows waste to decompose within your house and release smelly gases.

Clogged Vents

Your drainage system always has some waste — the waste cannot flow out of the house a hundred percent. Fortunately, good ventilation allows odors from the drainage waste to safely flow out of the house. However, vent blockages prevent waste from escaping and allow it to accumulate inside the house, causing your house to smell.

Dry P-trap

The P-trap is a U-shaped plumbing pipe near fixtures that handles the waste. You can see P-traps under sinks or behind toilets. The P-trap contains water that prevents sewer gases from flowing back into the house. The P-trap can dry, for example, if you don't use your plumbing system for a long time. The dry P-trap allows drain gases to flow back into the house.

Contact a plumbing contractor for a diagnosis and repair if you cannot diagnose or deal with your smelly drains. The contractor can also help you regularly maintain your plumbing system to prevent such occurrences in the future.