Man holding his nose to guard against sewer smellWhy do I smell sewer gas in my house?
Rancid. Noxious. Revolting. Repugnant. Stinky.

There are several reasons your plumbing systems are designed to seal out and vent the gases that come from your sewer lines, the first among them being the fact that sewer smell is quite unpleasant. If you notice a sulfur-like smell in your home, act immediately. Besides the offensive odors, the gases pose a serious threat to you and your family. Sewer gas is often composed of methane and hydrogen sulfide, which can cause headaches or other physical ailments. Even more daunting is the possibility of explosion, as high concentrations of methane are highly combustible.

There are two main causes of sewer smell in your home: open sewer traps and clogged drain vents. Let’s take them one at a time. 

What is a sewer trap?
A sewer trap, also called a P-trap, is a U-shaped bend in the pipes leading from all drains in the house. The curved portion “traps” water after it stops flowing, thereby forming a seal against gases that remain in your plumbing. Take a look in the cabinet under one of your sinks; you’ll see the curve there.

How do sewer traps open?
The most likely explanation is underuse. If a shower, sink, or toilet isn’t used very often, the water in the trap (or in the toilet bowl) can evaporate over time, breaking the seal against the harmful fumes and allowing them to enter your home.

What do I do to get rid of the smell caused by a dry trap?
Follow the steps in this simple process, using common household products, to eliminate odors from a shower or sink drain that is not often used:

  1. Ventilate the room by opening all available windows.
  2. Pour one cup of white vinegar into the drain, then ¼ cup of baking soda. Let it sit for two hours. You will probably want to close the bathroom door and put rolled-up towels against the outside bottom of the door to prevent the gases from leaking into other rooms.
  3. Pour one gallon of very hot water into the drain, followed by ½ cup chlorine bleach. Let this sit for another two hours.
  4. Turn on the shower and let the hot water run for about ten minutes. This should rinse the drain and allow the trap to fill with water again.
  5. Pour ½ c of mineral oil or cooking oil down the drain. This will slow evaporation, preventing future episodes.
  6. Leave the windows open and seal off the room overnight. The smells should subside by morning.
  7. Continue to perform simple weekly maintenance to keep the gases at bay. Simply pour a cup of vinegar down the drain and let the water run for ten minutes each week. For a rarely used toilet, regular flushing should avert any problems.
  8. If, by the next morning, the odors have not diminished, give us a call. We’re here to help. 

What is a drain vent?
A drain vent is a pipe leading away from your drain that serves as an exhaust system for sewer gases and helps maintain equal pressure within the plumbing system. You can see the top of the vent by looking at your roof – you’ll see a number of small pipes (or “stacks”) protruding several inches above the roof line.

How does a drain vent become clogged?
There are many different ways: birds may have dropped debris down the stack; trees may have shed leaves into the stack; the stack may become frozen over in the wintertime; materials from the gases can build up and clog the pipes over time. If the flow of gases is blocked in any way, they can back up into your home.

How do I clear a clogged vent?

  1. Locate the vent in question on your roof.
  2. Climb up to the roof using a roof ladder placed as close to the vent as possible. Hook the roof ladder over the ridge of the roof, taking care to secure it well. Bring a flashlight, a drain snake, and a garden hose up top with you. Bring a bucket of hot water if you suspect the stack may be frozen over.
  3. Access the vent and shine your flashlight into it, checking for any blockage that may be visible.
  4. If the stack is frozen, pour the hot water into the pipe to melt the ice. If your clog is not caused by ice, carefully feed the snake into the stack. When you encounter resistance, turn the handle counterclockwise so the snake can wind around the debris. Pull it up.
  5. Repeat step 4 as needed.
  6. If you were able to remove the clog, flush the line with the garden hose inserted two or three feet into the stack.
  7. If you were not able to remove the clog, do not attempt to push it out with water, as this could simply force the debris into a worse location. Give us a call. We’re here to help.