Sewer Gas Smell?

How to Fix It Yourself

Have you ever walked into your home and been slapped in the face with a methane smell that at first you couldn’t quite place?  What’s that rotten egg smell?  It’s sewer gas!

Not to be confused with natural gas which smells more like skunk and is very dangerous, methane gas is usually quite easily fixable, if you can figure out where the smell is coming from.

Here are some helpful hints on tracking down the sewer gas leak.

Dry Drain

Dry drain occurs when the water in your plumbing trap evaporates and allows the gas to escape.  Traps are designed to hold water in place thereby blocking any offensive gas from escaping the system.  If a sink, toilet, or floor drain is not used regularly, the water in the trap will evaporate.
Fixing this problem is simple; just pour some water down the drain to refill the trap!  If this situation seems to be recurring in the same trap over and over again, a plumber’s trick is to pour vegetable oil in the trap instead of water because it won’t evaporate.  This is usually done in unused floor drains versus sinks or toilets.

Cracked Pipe

A plumbing pipe that is cracked can be another culprit.  The hard part is to find the crack.  Look at all the plumbing lines carefully, paying special attention to fitting joints.  Once a crack is found, contact your local plumber to properly repair the crack.  Duct tape is not a proper fix for this one!

Dirty Pipes

Recently I heard an interesting sewer gas story.  The offender?  A pipe that recently had a sewer back-up.  The dirty sewer water coated the entire surface of the pipe and once the water receded, the exposed inside top of the pipe began to smell.  The owners scrubbed the pipe with some bleach and voila! Problem solved!

Blocked Roof Vent

Often, in the winter, snow and ice can build up on the roof vent creating pressure in the system which forces the sewer gas into the house.  A quick trip onto the roof to remove the offending build up will immediately fix the problem.  However, sometimes it is much trickier than that.  In other times of the year, the blockage can be inside the pipe and range from leaves and branches to birds and squirrels, oh my!  To check if the vent is blocked, use a hose to run water through the vent.  Listen closely as you run the water to hear if the water is going down or being ‘diverted’ to another part of the system.  NOTE: Running the water through the vent will not flood the system or your home.  If it does, you have a much bigger problem!

If none of these solve your sewer gas mystery it’s time to involve a professional.  The pros have years of experience diagnosing these problems as well as cool devices like gas ‘sniffers’ (no they’re not specially trained dogs).  Good luck!

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