Sewer gas & methane gas questions & answers:

This article answers commonly-asked questions about methane gas hazards: dangers of explosion or asphytxiation from methane gas from various sources such as septic tanks and sewers.

This article series explains Methane Gas & Septic System Dangers from Gases, gives basic advice, and cites additional reference material.

This article is part of our Septic Safety article series that outlines safety warnings & procedures for septic systems and cesspools, and provides safety suggestions for septic system inspectors, septic system inspections, septic pumping contractors, and home owners.

Methane Gas Hazard Q&A

These questions & answers about dangerous methane gases, septic gases, sewer gases were posted originally at METHANE & SEWER GAS HAZARDS - be sure to see the advice given there.

Watch out: as we report at SEWER GAS ODORS, potentially explosive levels of gases can accumulate in a building from several sources including explosive levels of sewer gas, swamp gas, or fuel gas from a variety of possible sources including plumbing leaks, improper plumbing venting, LP or natural gas piping leaks or errors, or even swamp gas accumulation under a building.

On 2018-10-24 by (mod) - explosion a few weeks ago outside my house

PCH

You need an on-site engineer or safety expert to track down the explosion and explosive gas leak you cite immediately. This is not something that's safe to try to debug by e-text.

On 2018-10-24 by PCH

There was an explosion a few weeks ago outside my house. The after shock was so strong it shook the no trespassing sign and stick proped in the window to the floor. There is sometimes a strong toxic smell in and outside the house. One morning God woke me about 430 am, my lips were numb and tongue felt like I had been eating hot sauce and the house was full of a toxic smell. Once outside a few minutes...the lip and tongue sensation went away. Is it possible that my problem could be meth dumping in a shared drain field or is it methane? Help??

On 2018-09-27 - by (mod) -

Larry,

That seems unlikely, but heck I have no idea, as I have no information about the site, soil, and possible gas passages.

For example a septic or sewer line itself could transport sewer gas underground.

Still, more likely if there were a sewer gas explosion from gases originating at the tank, we might expect the explosion to have included the tank itself.

Did you look at the construction of the fire pit, thermal expansion?

Are you in an area where there are natural methane gas sources underground, such as in a coal mining area?>

On 2018-09-27 by Larry Olson

I am the Park Manager of a campground. The bottom of a fire pit (concrete bottom, iron metal interior ring, exterior stone) recently "popped". Is it possible that the adjacent (50' away) buried septic tank
could have produced methane gas that traveled underground this far? There were no odors or other indications of gas present. This scenario seems unlikely to me, but I wanted to cover all possibilities.
Thanks

On 2018-04-12 - by (mod) -

Gee

I'd expect a building inspector, even though their scope is more-narrow, to notice a vent into an attic.

It's not a big deal to fix, and not a big deal as long as nothing happens.

If every stupid thing we do in construction resulted in a dramatic explosion we'd do it less often.

Don't argue about it with anyone, just fix it and move on.

On 2018-04-12 by Crystal

It wasn't the insurance inspector. It was a building inspector, we have to get permits from local government to do any building,local government sends government inspectors throughout the build to make sure all trades are doing things to code,with a final inspection at the end. I think venting would be at the top of this code,lol.There is nothing coming out of the roof to take a pic of,just the hole were the old stink pipe was,which the roofer shingled over,till they can fix it. The attic just a pipe coming out of floor about 6 inches with duct tape over top, roof hole about 20 inches away from duct tape,so they just forgot that finishing pipe that goes through roof. Thank you for the info, I know it's not safe thing, but talking to the contracter and the plumber who did it,there acting like it's not that big of a deal.ive been living here for the past 3 years not knowing but now that I know I don't feel safe anymore.. Not to mention there's been a hole in my roof for the past 3 years open to the elements.. I haven't talked to the inspector who did it,I do tomorrow,l'm sure he will just blow it off too. No one wants to take responsibility.

On 2018-04-12 - by (mod) -

Crystal / Anon:

Sorry to say I can't guess at just what topics the insurance company's inspector or other inspector was good-at and which left her stumbling in the dark.
What you describes sounds pretty obvious to me but then all I can see from here in Mexico is text.

Perhaps you could use the picture frame icon next to the Comment button below to attach a photo of the vent pipe in your attic as well as the roof surfaces from outside.

It's possible that insurance company inspectors are asked to focus only on specific items that the insurance company worries about: things that they think they'd have to pay for in a claim. Of course if the home blew up from a methane explosion that'd be embarrassing for the insurer.

Certainly if you hire a licensed home inspector, one who's experienced, not in a rush, and who works for you directly, you might get a more-comprehensive inspection.

On 2018-04-12 by Anonymous

This was a insurance gut job on my house. So it was inspected throughout the job. Wouldn't one of the top things on the inspectors list be looking for a stink pipe? They are coming to fix tomorrow. It could have been worse, my roof wasn't covered by insurance so I decided to do the roof,the roofer finds the empty roof hole and tells me no stink pipe,so it's a good thing I didn't wait another 5 more years to do the roof,or longer.

Do you know if I should make them look for other damage in house that could have been created by the no venting

On 2018-04-12 - by (mod) -

Crystal

What you describe is potentially unsafe - sewer gases that leak into an attic can cause a methane gas explosion.

In addition un-wanted moisture from a plumbing vent that leaks into the space can cause damage in an attic, including rot, mold contamination or bacterial contamination.

And of course taping over a vent means it's not venting that can in turn mean slow, clog-prone drains.

Your sewer won't have three years of gases accumulated: at least not at any significant pressure, since the drain waste vent system is not a high pressure system. Any pressure accumulated would burp out of the taped over upper vent end or out of a sink or tub or shower trap.

THis is an improper installation: the vent pipe needs to be extended through the roof to the outdoors.

On 2018-04-12 by Crystal

We just found in our newly rebuilt house,that the stink pipe is going in the attic with duct tape covering top. So pretty much not doing anything because it's sealed with duct tape. It's been that way 3 years now. So what happens? is my sewer now backed up with 3 years of gases? On if so is that a harmless thing?

On 2018-02-22 by (mod) -

You need to discuss these concerns with your doctor first and then if she agrees your health department. Just hiring someone to do non specific test is actually a bit risky.

On 2018-02-22 by (mod) -

AUTHOR:Jessica Perry (no email)

COMMENT:Hi, at my apartment in Providence- 810 Douglas Ave Providence RI 3rd floor with electrical and furnace involvement consisting of multiple valves with gas black piping, it has lead me to multiple hospital admissions with MS symptoms as presentation along with headache, dizziness, and altered thought process due to inhalation of toxic gases too

Presently I believe there is a dangerous situation with the HVAC AC system and with the air quality of such pertzining to. I reside at Millenium house in Hollywood FL currently. Please call me to set up testing. 401 636 8322

. Thanks, Jess Perry.

https://inspectapedia.com/noise_diagnosis/Hissing_HVAC_Noise_Diagnosis.php

On 2018-01-31 by (mod) -

The suitability of a respirator as opposed to an actual Air Supply would depend on your actual environment -

Some respirators can handle low levels of gases safely but at high levels there's no doubt that a respirator would not be adequate.

On 2018-01-30 by Carl

Can I get respirator

On 2017-04-25 by (mod) -

Ed,

Yes you raise an excellent safety question. Indeed a spark at the septic tank can cause a methane gas explosion. We've had several reports of just that sort of thing happening: explosions when a septic worker standing by an open septic tank lit a cigarette and a big explosion when a homeowner burned brush over the septic tank.

A fire expert can probably list steps to minimize the hazard. I'm no expert but I'd imagine you'd both ventilate the tank and area and perhaps keep the cutting location wet enough to avoid sparks.

Watch out: even leaning over an open septic tank can cause fatal asphyxiation.

On 2017-04-25 by Ed

We are needing to cut a hole in the lid of our septic tank lid for a cleanout, question is if by chance we hit a piece of rebar and get a spark is there a chance of exploding?

On 2017-04-06 by (mod) - toilet wax ring leak fiasco

Geri

I'm sorry to hear of such terrible plumbing work.

We should focus first on making the home sanitary and safe. That means more than just making a proper plumbing drain connection. THe sewage under the floor needs to be removed and the area disinfected / sanitized.

In addition you will want to describe these conditions to your doctor.

I don't know what . who is "mediawavier" but before considering legal actions let's focus on health and sanitation as the immediate concerns.

On 2017-04-06 by Geri

I have been noticing a smell coming from a bathroom that was remodeled by a contractor that mediwavier hired to make handicapped shower and bathroom.. This had been done years ago.. 5-7 years ago.. I have no way of knowing the contractor he was hired by the state. Well today I had a son in law come and check wax ring to the toilet.. What we found was unbelieveable...

The wax ring that was placed under the toilet was not even connected to the sewage drain.. there was fecies and tissue everywhere under the flooring...

My daughter and I have both have major illness.. I have cancer and also heart issues and my daughter has liver problems... My son in law fixed the problem but what are if any actions that I could take .

On 2017-04-02 by (mod) -

Katherine

While no one can assess the safety of your home by a text, it is my opinion that if you smell sewer gas in a building there could be methane gas hazards as we described in this article series.

On 2017-04-02 by Katherine E

For the last three months we have had a nightmare trying to locate the sewer pipe that leads from our property to the main sewage on the street.

We are quite a distance off the street. Luckily we have an overflow tank that any excess sewage not being pumped into the street is currently being held in. There is now a very strong smell of sewage in the house which has built up over the last two months

. I am still having to live in the property whilst they continue to try to locate the pipe. We have had three contractors out and no one has found it yet. I am concerned reading your articles that I could be at danger of explosion or suffocation.

There is a gas central heating unit in the same room as the sewage tank, but we are not using that at present because of the smell that it circulates. Can you tell me if I am at risk in the property whilst they fix it.

On 2017-02-19 by (mod) -

Karyn, I cannot guess what may be making the sounds you describe. A methane gas explosion would be dramatic and would require both an accumulation of methane gas and a source of ignition - a spark or flame.

Before testing for methane I think an on-site inspection by an expert, or if you think there are actually explosions occurring, vacate the property and call emergency services immediately.

On 2017-02-19 by Karyn

I keep hearing explosion like sounds outside my house. My septic system is outside and last year I had work done on it could this be related? Is there a test I can have done for gases to conclude that this is the reason for the noise?

 

On 2017-02-19 by (mod) - explosion sounds from yard

Karyn, I cannot guess what may be making the sounds you describe. A methane gas explosion would be dramatic and would require both an accumulation of methane gas and a source of ignition - a spark or flame.

Before testing for methane I think an on-site inspection by an expert, or if you think there are actually explosions occurring, vacate the property and call emergency services immediately.

On 2017-02-19 by Karyn

I keep hearing explosion like sounds outside my house. My septic system is outside and last year I had work done on it could this be related? Is there a test I can have done for gases to conclude that this is the reason for the noise?

On 2016-11-08 by (mod) - building a block patio over the septic tank

The dangers I can suggest are outlined in the article above: creating a spark - and thus an explosion are immediate risks; I'd also want to be sure that not only is there easy access to all of the cleanout openings (there may be 3) but also to the tank ends and entire cover should later repair be needed.

If your "block" patio means simply dry-laid concrete blocks, and IF the septic tank cover is one rated as strong enough to support the weight and traffic involved you may be OK.

Be sure to avoid heavy traffic including machinery running over septic lines, tank, or over the drainfield.

On 2016-11-08 by Bryan

I have a new house with a septic system. I want to build a block patio over the tank leaving access to the cover and use the patio for a fire pit area. Any dangers of gasses from the septic tank?

On 2016-07-31 by (mod) - lingering methane gas problems

Interesting question and not one for which I've found expert advice. Perhaps if your outhouse floor plan includes a durable impermeable vapor barrier you'll avoid a potential methane hazard. In any event a generator cannot be safely run inside an enclosed space without fresh air and combustion air.

On 2016-07-30 by Diane

I have a question about filling in an old outhouse. After we fill it in, we would like to convert the outhouse to our generator "doghouse." That would involve filling in the hole, covering the hole, insulating the room (to cut down noise), and adding some vents in the walls.

I'm wondering if there's any problem with potential lingering methane gas and using a gas-powered generator. Anyone have ideas/experience we should consider? Thanks!

On 2016-01-22 by (mod)

Gene

It is common in many countries and communities to install plumbing that does not meet North American or European standards, including missing or inadequate venting; the risks are just what we think: poor drainage, sewer gas backup into the building, odors, and in some cases even an explosion risk.

Venting into an attic is also a bad idea: the vent needs to extend to outdoors not to dump sewer gas and moisture into an enclosed space.

I'd prefer to vent fixtures to the outdoors.

On 2016-01-22 by Gene Pothier - methane gas hazards in the Philippines

Hello,

I recently retired to the Philippines and purchased a home here and is under construction. During one of my routine inspections I noticed a few things that just did not seem correct to me with the plumbing.

Listed as follows (Please note: all homes here use a septic tank):

1) Sinks, toilets and shower drains have no vents.

2) Only source of venting is through the main drainage system which vents into the attic. Attic has no source of ventilation except from soffit openings at the 4 corners of the roof. There is no way for the heat to escape or any form of proper ventilation to take place and it does get hot here.

My question(s) is/are simple; as follows:

1) Does this pose a hazard of any kind? If so what are they?

2) Any suggestions as to a "fix" of improper plumbing?

My 1st question is the more important of the two as your reply will probably answer question 2.

Thank you in advance for any help/suggestions.

Gene Pothier
Gene56_2006@yahoo.ca

On 2016-01-09 1 by (mod) fuel cell energy park.

Brian you ask an important question, not to mention the un-mentioned one of the very large volume of water being wasted daily.

One cannot answer the question without knowing not just what contaminants may be in the waste-water stream but also what pre-release treatment is going to be done to the wastewater before it is released to the environment.

Surely a project such as this one had to file an environmental impact statement - if you're in the U.S. - and that's a public document. Check with your local building authorities to ask where you can obtain a copy. Keep me posted.

Also see

• Liu, Hong, Ramanathan Ramnarayanan, and Bruce E. Logan. "Production of electricity during wastewater treatment using a single chamber microbial fuel cell." Environmental science & technology 38, no. 7 (2004): 2281-2285.
• Sharma, Yogesh, and Baikun Li. "Optimizing energy harvest in wastewater treatment by combining anaerobic hydrogen producing biofermentor (HPB) and microbial fuel cell (MFC)." International Journal of Hydrogen Energy 35, no. 8 (2010): 3789-3797.
• Spiegel, Ronald J., and J. L. Preston. "Technical assessment of fuel cell operation on anaerobic digester gas at the Yonkers, NY, wastewater treatment plant." Waste Management 23, no. 8 (2003): 709-717.

On 2016-01-09 by Brian

I live near a proposed fuel cell energy park. To convert the natural gas into hydrogen, the process will consume 300,000 gallons of water a day and discharge 150,000 gallons of wastewater to its wastewater infiltration system. Is this wastewater toxic? Will it give off any smell? Will it seep into our groundwater? I have a well; will it contaminate it?

At OUTHOUSE / LATRINE FIRE & EXPLOSION we describe a methane gas explosion in an outhouse - admittedly an unusual event.

Also see BACKDRAFTING & SEWER/SEPTIC ODORS

On 2013-02-08 by Rick

We use porta-potties in the mine where I work, we are a kilometer deep and have a cascading airflow that follows one path throughout the entire mine before being vented to surface. On a bi-weekly basis our company has an outside contractor come in and empty these porta-potties, using a small trailer mounted vac-truck.

The smell that comes from this truck is absolutely horrendous for anyone working downwind of it. Is this vented gas and particulate matter dangerous, if so what can be done in the way of filters to protect our workers?

On 2012-10-18 by Robin

This is the second year I have taught in a school close to 11 years old. We've had a septic smell and/or mildewy smell in different parts of the building coming out of the ceiling. Less than two weeks ago most of us experienced what truly felt like an explosion. (It was not an earthquake, lightning, trucks going by,etc.

) It seemed to be moving through the building and we felt it in our feet as well as hearing it. A few days latter we had a staff meeting.

The principal addressed the smell we were all having in our rooms at a meeting a couple of days later. He explained to us that when the building was built the stink pipes do not go up out of the roof.

They are vented between the ceilings and roof. The pipes have to be kept wet inside and some had become dry, due to new people on the job not being "sure" how to take care of them.

I thought it all sounded " far fetched" I asked point blank if the sense of an explosion that many of us had could have been a methane gas explosion. His response was to mostly diminish it. How can stink pipes be vented between the ceiling and the roof in a fairly large building without causing problems.

Don't all "stink pipes" have be to be vented to the outside? Can little rumbles like we heard and felt be an indicator that something it wrong and might even get worse?

On 2012-10-07 1 by (mod) -

Lisa Karen,

I'm unclear if the plumbing vent you describe is terminating indoors or outside; if outside and if it meets horizontal clearance distance from windows, it may comply, though if you're in a freezing climate there may be trouble nonetheless. If it's indoors the installation would not comply with building codes and standards.

Steve,
I have not encountered and am doubtful that gas pressures in a septic tank would explain concrete septic tank wall movement of any kind.

First, concrete walls don't bend and displace -the concrete would fracture or break; second, before gas pressure in a septic tank would exert significant pressure on the tank structure enough to break the wall, it would be expected to move the top and vent, or well before either of those, it would be expected to bent out through the inlet our outlet piping to the septic tank itself.

On 2012-10-06 by Lisa Karen

We have a newly built log house, 3 floors, 2 1/2 bath.The plumber did not run the pipe out the roof, like I have been familiar with. He stopped it just above our shower, left open

and I can here it when we flush, the swoosh and water gurgle.Is it dangerous for escaping gasses.It is on the 3rd floor which is an open plan, 1/2 is bathroom ,other 1/2 is bedroom so the air flows freely.

On 2011-11-14 by steve asks:

Considering a tank with concrete walls and flat concrets slab roof, is it possible for pent up gas to displace a side wall outward...such that gap opens that, to greater or lesser degree, permits soil to enter the tank...in particular, at times that the soil overburden has been removed/disturbed during pumping procedures?

What can be done to repair/prevent recurrence? I'm thinking about filling gaps with expanding foam.

Then providing overpressure relief in the form of some kind of pressure relief valving/venting setup. The the vent would consist of pipe connected to knockouts in newly installed risers, said pipe(s) leading to a non-mown area where they could emerge above grade level and release any released gas through a filter of some kind and then into the air. You thoughts on these questions and design approaches, please.

On 2011-10-03 by (mod) -

Dustawaits

this doesn't sound right - cisterns are used to store drinking water; probably you meant a "cesspool" - SEPTIC & CESSPOOL SAFETY in the ARTICLE INDEX is where you can find more about cesspools and their hazards.

On 2011-09-24 by Dustawaits

I have just found out that the sewage from at least part of the house is going into a cistern. The cistern is not vented and I do not know how it even empties, do not know the size of the cistern or anything about it. There are extremely strong gas smells and my health is going downhill rapidly. I am now carrying a headache that will not quit. I just learned this info on the cistern 2 days ago and and am working on leaving the place. But packing and such still leaves me in contact- Any suggestions?

On 2011-09-14 by Seabreeze

My home has been having an odor in spots around an old septic tank that has not been filled in .What does methane gas smell like? This odor takes my breath away. It is kind of bleachy .

On 2011-08-24 by (mod) -

Anon We're not lawyers, but I'm doubtful that a local building department or health department would agree that it's safe for sewer gases to be leaking into a building. Not only are there sanitary and odor issues, methane gas is explosive. And the case you describe sounds quite unsanitary too.

Notify the landlord in writing of unsafe unsanitary conditions and ask that they be repaired immediately. If the landlord refuses to respond and presuming your description is accurate, you may have no choice but to ask for help from your local health department or building department.

On 2011-08-22 by Anonymous

our home has a drain from toilet that is exposed and leaking gas into our house. The smell is rotten egg smelly and seems to cause headaches. the landlords say it is legal, is this legal. We can flush our toilet and literally see the waste floating down the pipe from an open hole.

On 2011-07-18 by (mod) -

Jim: the concern for septic smells in your office is not just an unpleasant odor but also there could be the risk of a methane explosion. You need expert advice from your local board of health and building department.

On 2011-07-14 by Jim

My office sit on top of septic tank. For the last few years we have had issues with smells and they now have the tank empty every 3 weeks. Also they put up a flow vent out the wall since there is now were else for the smells to go. They don't have a leak field. I have been having issues with sinuses for about 3 years and gettng worse. Should I be concerned?

On 2011-05-20 by (mod) -

This is too risky a question for me to offer a confident answer with so little information, but in general, if septic effluent itself is leaking into the structure that is certainly unsanitary and unsafe, and even if no septic effluent leaks into the building itself, if septic gases are entering the building those too could be unsafe, risking a methane gas explosion.

You need to find and fix the effluent leak.

You might need to have the basement or crawl space floors sanitized and sealed.

You could have an expert take bacterial swab samples from home surfaces, including the lowest floor where leakage may be at greatest risk. If lab analysis of those samples shows coliform or fecal coliform bacteria at abnormal levels then it would confirm that there has been leakage and that cleaning and sanitizing are certainly needed.

See our article titled SEWAGE CONTAMINATION in BUILDINGS for which you'll find a link at page left.

On 2011-05-20 12:55:32.684170 by Tammie

I was told that since our septic system has been slowly leaking under my home It would put my family at risk for staff and other deases. Is this true and what do i do

...

Continue reading  at METHANE & SEWER GAS HAZARDS - topic home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Methane Gas Hazard Articles

• BACKDRAFTING & SEWER/SEPTIC ODORS
• METHANE GAS EXPOSURE LIMITS
• METHANE & SEWER GAS HAZARDS
• METHANE GAS HAZARD FAQs
• METHANE GAS SOURCES
• PLUMBING S-TRAP CODES & HAZARDS
• PLUMBING DRAIN NOISES how errors cause trap siphonage, odors, and noises
• PLUMBING SYSTEM ODORS - home for guidance in tracking down plumbing smells
• SEPTIC & CESSPOOL SAFETY
• SEWER GAS ODORS
• TESTS for SEWER GAS INDOORS
• TOXIC GAS TESTING - Methane Gas Hazards

• TESTS for SEWER GAS INDOORS

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METHANE GAS HAZARD FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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INDEX to RELATED ARTICLES: ARTICLE INDEX to GAS HAZARDS in BUILDINGS

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