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Photograph of melting snow indicating septic tank locationFind & Fix Cold Weather Septic / Sewage Odors

Sewage odor tracing procedures:

Tracing odors occurring in cold weather.

This article describes approaches to track down the actual sources of sewer gases in or around buildings when those are observed principally in cold or freezing weather.

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How to Find & Fix Sources of Septic Odors that Occur in Cold Weather

Plumbing vent beginning to clog with snow (C) Daniel FriedmanSome of the diagnostic steps given here pertain to all seasons. But here we focus on cold-weather-related sewer and septic odors in or around buildings.

At left is a plumbing vent that was almost entirely blocked by frost.

[Click to enlarge any image]

Smelling sewage odors inside only, or mostly inside

Here are some places to look and perhaps to fix if you're smelling sewage or septic like odors inside of a building:

You can usually spot inadequate or blocked plumbing venting

by noticing, for example, that tub, shower, or sink drain makes a gurgling or "glub glub" sound when a nearby toilet is flushed or when a full fixture is being drained. Inadequate or blocked plumbing venting can also mean that a plumbing fixture does not drain well (even though the drain line is not blocked). Inadequate venting produces a glub glub sound as water passes down a drain and cannot draw air in after itself through a plumbing vent stack.

Photograph of melting snow indicating septic tank location

Instead the drain has to draw air in to itself through various plumbing traps which, as they normally contain water, produces the glub glub sound as air passes through the trap. This defect can siphon water out of traps and let sewer gases back into a home - smelly and potentially dangerous (methane gas).

Also see PLUMBING DRAIN NOISE DIAGNOSIS: that may indicate defective or clogged plumbing: how to diagnose and cure drain sounds.

Photograph of melting snow indicating septic tank location

How to improve sewer or septic gas or methane gas smell source location by considering the effects of weather conditions or season. Causes and cures for sewer gas odors related to wet or cold weather. How to find and cure bad smells in buildings using site and outdoor conditions as diagnostic

Some of the diagnostic steps pertain to all seasons. The photograph provides a lot of septic odor diagnostic information if you look closely: there is a home made septic tank nearly touching the building wall (by those steps), and in the foreground is a pony pump that the owner was using to try to move septic effluent uphill to his drainfield.

This system would not work reliably: the tank is too small for normal use and the pump is exposed to freezing.

Cold Weather Sewer/Septic Odor Clues that Do Not Point to a Frozen Drainfield

If you're using the building plumbing, drain, and septic system and it's not backing up it's not so likely that the problem is a frozen septic field.

There could be a drain vent line problem such as a frozen vent line (frost from moisture moving up the vent line above the roof from use of that drain for laundry or showering).

Be sure the traps in the lower bath are not dry as a dry trap will often send sewer gases into a building.

Cold Weather Sewer or Septic Gas Odor Sources

Check out the above items first. But take a look at these cold weather sewer gas or septic gas sources that may show up more noticeably when temperatures outside are falling or when the outdoor air is still such as in evenings.

Photograph of red septic dye staining snow over a failed septic system in winter.

See PLUMBING VENT DEFECTS & NOISESfor diagnostic details of venting problems

and see PLUMBING FIXTURE TRAPS for fixture trap inspection and defect diagnosis.

Also see METHANE GAS SOURCES and

See our broad-scope article on diagnosis and cure of sewer gas and septic odors:

SEWER GAS ODORS diagnosing, finding, and curing septic tank and sewer line smells.

 




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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Reader Question: septic issues in Connecticut during cold weather

Do you know of someone in the southern Connecticut area that has extensive knowledge about troubleshooting septic issues?

I have had 3 different septic companies and 3 plumbers to my house and no one seems to be able to troubleshoot the problem.

Cold weather sewer odor symptoms:

For example, when the shower is used for more than about 3 minutes.

When the toilet is flushed several times and the sink is used to wash hands within a short period of time.

This ONLY happens when it is cold outside (below 40 degrees or so).

There is no smell when the temperature outside is above 40 degrees or so.

One of the septic companies removed the toilet and ran a camera and checked the structural integrity of the line.

He also dug to inspect the dry well and said that there were no issues that he could see.

He then had the dry well cleaned out. Since I didn't even know that this dry well existed, it had been 8+ years at least since the dry well had last been cleaned out. The clean out was performed in August 2013 and the gas odor returned in October 2013.

Since all the basement utilities are used daily, lack of water in the traps has been ruled out as an issue.

I have not been able to identify if there is a vent for the basement.

The rest of the house is on a separate septic tank and there are no issues with that. - C.E.T. 12/10/2013

Reply:

At https://InspectAPedia.com/home_inspection/Home_Inspectors_Directory.php you might find an experienced home inspector who has septic system expertise too, or who may be able to make a competent suggestion - offer to pay them for a brief consult if necessary. I presume you've checked out the cold weather septic odor article beginning above

at SEWER GAS ODORS in COLD / WET WEATHER  ?

It's too bad but true that often to get competent help we have to learn something about the problem ourselves.

I'd be sure to rule out the obvious (loose toilet, slow drains, frost-clogged plumbing vent) before doing anything expensive.

If there are un-vented plumbing fixtures in the basement that's certainly likely to be a year-round problem not just a winter problem;

Ask yourself what's different in winter - not just that it's cold outside, but that the heating system is on, windows are shut, in sum: the air flow patterns in the building change, and there may even be backdrafting due to closed house plus operation of heating equipment (which would be unsafe).

And re "Since all the basement utilities are used daily, lack of water in the traps has been ruled out as an issue."

If there is a basement floor drain that connects to the sewer or other drain line, it can indeed run dry any time, or may not even be properly trapped. Try to narrow down the odor source by odor strength, time of day, equipment on or off, doors open or shut, etc. 

Reader follow-up:

Sewer gas odors at washing machine drain hookup (C) InspectApediaI was able to find the source of the smell by running the shower for a long period of time and then seeing where the odor was coming from first.

The odor is coming from the hole where the white tube that is running from the washing machine goes into. I imagine that the hole, which I am sure leads to the dry well, is not trapped or not trapped properly. I attached a picture.

[Click to enlarge any image]

Reply:

Indeed it is not uncommon for an installer to fail to properly trap and vent a washing machine drain, and drywells, while not usually as smelly as septic tanks, can send odors back into a building.

Pending opening the wall to inspect the piping and install a proper trap on the washer drain you could stop odors from entering at the washer drain hose connection by makeshift-sealing the connection between the flexible washer drain and the pre-fab drain connection shown in your photo.

Reader followup:

Thanks, I was wondering if there was a way to seal it instead of opening the wall.  I will call a plumber and see what he can do to make the seal. 

Reply:

First try a simple DIY project - you can use a bit of insulation and duct tape - just be sure you don't drop insulation or crud into the drain as you may block it if you do.

As a seal in this location is non-standard, your plumber won't be any smarter than you are. And I would NOT use caulk or something that would glue the washer drain hose to the connection or it'll be hell to remove it later.

Reader follow-up:

Ok, thanks for the tip.  I will give it a try.

and see PLUMBING FIXTURE TRAPS for fixture trap inspection and defect diagnosis.

Also see METHANE GAS SOURCES and

See our broad-scope article on diagnosis and cure of sewer gas and septic odors:

SEWER GAS ODORS diagnosing, finding, and curing septic tank and sewer line smells.

 

On 2018-12-18 by Kim

Thank you

On 2018-12-17 by (mod) - smell sewer gases at the outlet opening of a plumbing vent pipe.

Kim

Yes it's normal to smell sewer gases at the outlet opening of a plumbing vent pipe. That's in fact why proper installation requires the pipes to place their final vent opening above the roofline.

However it's quite abnormal to find the vent line full of water. Unless you could actually see all the way down a vent to a plumbing trap that suggests to me that there's a blockage or something is wrong and you need a plumber to investigate further.

On 2018-12-17 by Kim

Greetings - Is it normal to smell sewer odors at the top of a sewer vent pipe? I feel like this is a really stupid question because common sense tells me that, yes, if you stick your nose into a sewer vent pipe you will smell sewage gases.

Background: Just had roof repair done and roofer raised concern that the sewer vent pipe might be blocked because he could smell sewer gas in the sewer vent pipe. He also said he looked inside the pipe and it was "full of water".

I went on the roof after he left. I saw no standing water in the pipe, though there was some condensate since we do live in a cold climate. I sent a 16 foot plastic pole down the vent pipe (used for apple picking) and detected no obstructions all the way down to the point where the vent originates in the basement

I did, though, smell sewer gases if I literally stuck my nose over the end of the vent pipe.... Thanks for reading!

On 2018-01-27 by (mod) - ice is forming from sewage effluent on a septic mound

Anon

If the ice is forming from sewage effluent that suggests that the mound is no longer working acceptably.

You may need to wait for better weather to get more detailed diagnosis and a bid on repair or rebuild; an inspection in the septic tank or D box can tell you if the system is also backing up - risking a sewage backup indoors.

On 2018-01-27 by Anonymous

I have ice formations on 2 sides of my septic mound

On 2018-01-08 by (mod) - using root killers in the drainfield

No, Cindy. See ROOT KILLERS in SEWER LINES or SEPTIC PIPES https://inspectapedia.com/septic/Root_Killer_for_Soakaway_Beds.php for details about products like the one you named.

My diagnostic and thus repair suggestions for cold weather septic gas problems are in the article above.

On 2018-01-08 by Cindy

Will rid x get rid of septic gassed during the extreme cold weather ? If not what will ? This only happens during cold snaps when below 30 degrees

On 2017-12-30 by (mod) - sewer smell from air ducts on cold nights

Have the duct interiors been inspected for leaks or animals?

On 2017-12-29 by r cook

We have been experiencing a sewer like smell for two years now, only on very cold nights (never during daytime even if it is very cold and heat is pumping). And only coming from certain heat ducts in the house

On 2017-09-09 by Barb

We've been experiencing an ongoing nasty sewer gas smell whenever our toilet is flushed - moreso in the cold/wet/winter weather than in the warm summer. The vent pipe on the roof is not blocked. We replaced the toilet seal a couple of times, the last time with a wax ring.

We did have a plumber out and he added another wax ring to the one one we had recently installed. After he left, the smell was GONE, (this was in cold January) but it only lasted for 2 weeks, after which the smell returned. It seems like the problem is the toilet seal - we're just not getting a good seal....

can anyone recommend a product, or procedure, that will work? We have also tried the rubber/vinyl type gasket seal, which didn't work either. Cold weather is coming and we're starting to get a hint of the bad smell again....need to fix this before it comes! Thanks.

On 2017-06-01 by (mod) - occasional odor with from an aerobic septic system may be normal

From our readers who use aerobic septic systems, and from the manufacturers literature, I have learned that an occasional odor with from an aerobic system May in fact be normal. I do not recommend using any septic additives such as the one that you named.

There are some Aerobic System designs that do require specific additives named by the manufacturer. So we would need to know the manufacturer and type of your system to research further.

On 2017-06-01 by Greg

I have an aerator septic system and at times I can smell a wisp of the septic tank. After opening the cover the system looked normal except the waste looked thicker than normal even though the air was pumping through as normal.

The discharge water looked clean as always. I just had it pumped off last year. Is there something else I should be doing. I haven't used any Rid X or anything like it.


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COLD WEATHER SEWER ODOR SOURCES at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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