If your smelling sewer gas or a methane gas in a room, ceiling, wall, or any room for that matter you can trouble shoot the leak by using peppermint oil.
You can purchase peppermint oil at some plumbing supply houses and on Amazon.com.
The reason for Methane gas odors are a variety of reasons.
1.) Poor plumbing installations.
2.) No plumbing test
3. Poorly manufactured piping material. The thickness of the pipe might not of been the same the entire length of pipe even after a proper plumbing test. It may take a few years but that piece of pipe weakens and you get a pin hole leak.
4.) Plastic pipe was installed either a chemical pipe for commercial buildings or the plastic pipe used in homes was not properly installed with enough room for expansion and contraction and the pipe separated, split, or cracked.
5. ) Old pipes 30-50 years old are leaking at joints of galvanized pipe, cast iron, lead, durion, etc.
6.) During the course of a new remodel job a piece of lath or drywall was removed and pulled a screw out of a piece of pipe that was lodged in it for years and know leaks during the remodel.
7.) If I left out anything out than it was because it was probably caused vandalism, or revenge by someone.
Testing for leaks:
The first step is trying to determine where the odor is coming from. Is it in the ceiling, wall , floor, or a particular room.
Use the buddy system which is two individuals, one on the roof and the other in the room or area of the sewer smells.
The person on the roof will put two ounces of peppermint with one quart of very hot water down a vent. The other person try’s to locate the odor using his nose and eye’s. If you have a leak you will be able to locate it pretty easy because you will find the odor to be very strong and come from the area where the hole is.
Take a look at this picture.
The picture shows how a cloths washer is piped behind the wall or similar fixture.
You have a clean out on the left lower bottom. The clean-out has a screw plug.
When testing the sewer and vent lines on new installations you remove the screw cover and plug off the sewer with a plug, chernie, or cap and run a water or air test. ( see pictures of plugs and caps below).
Follow the vent upward and out the roof to see how it is piped. See next picture.
This is the vent line running out of the roof. When you the peppermint drops with water these are the pipes your checking for leaks. You could have a leak in a 90 degree elbow or a piece of pipe leaking.
Granted the walls and drywall is in place and it’s not this simple, but you get the picture.
You would do the same test if you have a variety of vents and fixtures. Always keeping the guy away from you who smells like peppermint.
If you cannot locate a leak with this method, the next step would require you to disconnect the sewer at a low point and and cap the sewer off. If you need to do this I suggest you hire a plumber. See picture of caps and plugs to put in sewer.
I have another method of testing for methane gas leaks on Bukisa using the smoke test. Check it out.
Amazon.com has my new book for sale and you can look through it by going to there web site. The book is called “Flush Your Plumbing Troubles Down The Toilet’.