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ODORS GASES SMELLS, DIAGNOSIS & CURE
AIR POLLUTANTS, COMMON INDOOR
AIR QUALITY IMPROVEMENT STRATEGIES
ALLERGEN TESTS for BUILDINGS
ANIMAL ODORS IN BUILDINGS
BACKDRAFTING HEATING EQUIPMENTAQ
BIOGAS PRODUCTION & USE
BOOKSTORE - ENVIRONMENTAL
CARPETING & INDOOR AIR QUALITY
CHINESE DRYWALL HAZARDS
CHEMICAL CONTAMINANTS in WATER
COMBUSTION GASES & PARTICLE HAZARDS
DIRECTORY of MOLD / ENVIRONMENTAL EXPERTS
Disinfecting Buildings with Bleach
DUCT SYSTEM & DUCT DEFECTS
DUST SAMPLING PROCEDURE
EMERGENCY RESPONSE, IAQ, GAS, MOLD
FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
GASES, EXPOSURE, TESTING
GAS DETECTION INSTRUMENTS
GAS EXPOSURE LIMITS & STANDARDS
INDOOR AIR QUALITY & HOUSE TIGHTNESS
INDOOR AIR QUALITY IMPROVEMENT GUIDE
INDOOR AIR QUALITY METHODS COMPARED
LIGHT, GUIDE to FORENSIC USE
LP & Natural Gas Safety Hazards
Legionella Legionnaires' Disease
METHANE GAS SOURCES
MILDEW in BUILDINGS ?
MOISTURE CONTROL in BUILDINGS
MOLD: A COMPLETE GUIDE to TEST CLEAN PREVENT
MOLD ACTION GUIDE - WHAT TO DO ABOUT MOLD
MOLD EXPERT, WHEN TO HIRE
MOLD or INDOOR AIR EMERGENCY RESPONSE
TEST KITS for DUST, MOLD, PARTICLE TESTS
MVOCs & MOLDY MUSTY ODORS
ODORS GASES SMELLS, DIAGNOSIS & CURE
OUTHOUSES & LATRINES
OZONE for MOLD OR ODORS
PLUMBING SYSTEM ODORS
SEPTIC & CESSPOOL SAFETY
SEPTIC SYSTEM ODORS
SEPTIC TREATMENTS & CHEMICALS
SEWAGE & SEPTIC CONTAMINANTS
SEWAGE CONTAMINATION in BUILDINGS
SEWAGE EJECTOR / GRINDER PUMPS
SEWAGE PATHOGENS in SEPTIC SLUDGE
SEWAGE BACKUP, WHAT TO DO
SEWAGE BACKUP TEST & CLEANUP
SEWER GAS ODORS
SEWER LINE REPLACEMENT
SMELL PATCH TEST to Track Down Odors
STAIN & BIODETERIORATION AGENT CATALOG
STAINS on & in BUILDINGS, CAUSES & CURES
SULPHUR & SEWER GAS SMELL SOURCES
THERMAL IMAGING MOLD SCANS
UV LIGHT BLACK LIGHT USES
VENTILATION in BUILDINGS
Volatile Organic Compounds VOCs
WASTEWATER TREATMENT BASICS
WATER ODORS, CAUSE CURE
WATER TESTS, CONTAMINANTS, TREATMENT
WATER TEST CHOICES & WATER TEST FEES
WATER TREATMENT EQUIPMENT CHOICES
WATER, WELLS, WATER TANKS: TESTING GUIDE
WETLAND SEPTIC SYSTEMS
Cold-weather-related sewer or septic system odors: this article describes how to diagnose and correct sewer gas or septic odors (and other building smells and odors with focus on diagnosing odor sources and causes in cold weather. This article on diagnosing sewer gas or septic odors is a special cold-weather edition of our more general advice on finding and curing sewage odor problems. Here we focus on sewage or septic odor problems that occur during cold weather or wet weather. Also see Backdrafting & Sewer/Septic Odors This article describes sewer odors due to a combination of wet weather and building back-drafting. Also 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. Citation of this article by reference to this website and brief quotation for the sole purpose of review are permitted.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
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. Our sewer gas odor diagnosis articles are grouped into SEWER GAS ODORS and SEWER GAS ODORS in COLD WEATHER - the article found below on this page
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.
Tips for Tracking Down Hard-to-Find Sewer Gas Odors in buildings
Other Sources of Sewer Gas or Methane Gas Odors in buildings
Others with whom we have worked on tracking down sewer gas odor problems have
Frequently Asked Questions (FAQs) on tracking down cool weather and night time sewer gas / septic tank smells
Question: on cool summer nights we smell septic gas, always at the same place, how do we fix this odor?
But in the cool of evening not only do temperatures fall, but typically wind velocity falls as well. Under those conditions even a modest smell problem can become more noticeable because the gases are not being dissipated by air movement, and may even be falling towards ground level as escaping plumbing gases are cooled in the night air and, counter intuitively, might even ride descending air currents that during warmer daylight hours, would instead be rising air currents.
Your suggestion of adding a filter to try to reduce odors is a band-aid approach that has some risks: you might be better off to track down the odor source to see what it means. For example, improper plumbing venting can be unsanitary or even dangerous; and obtaining an early warning that the septic drainfield is failing may be useful in planning for repair or replacement of the system.
Tracking Down Sewer Odors Outside
Because you notice the odor at a particular location - at the rear of the house, and at a particular time - in evenings, that's a good time and place to start tracking the odor to its source.
If by "rear of the house" you mean outdoors, sniff towards the septic tank, drainfield, or any sewer line vents (see our photo at above left) or sewer line cleanouts that might be installed between house and septic tank.
Tracking Down Sewer Odors Inside
Question: neighborhood sewer gas smells
our whole section of town often smells of sewer gas! it is noticible for 2 or 3 blocks. what's up with that? p.s. - most often is worse when it cools down after a warm day or during the monsoons.. - Sharon 7/22/11
Sharon when there is a sewer odor in the neighborhood, if your homes are on private septic systems I suspect someone's drainfield is in failure. If we're talking about a community where every home is connected to a municipal sewer, there could be a burst line, effluent breakout, a problem with a pumping station, or the odor could be from something else.
Question: cesspool odors that stop when the rain stops - smells during heavy rains
I would like an opinion. I have a cesspool, it has been pumped out even though the gentlement said it did not need it. Everytime we have heavy rains in our area I get a foul smell inside my home;. when the rain stops the odor goes away. I had it poumped thinking that was it but the cesspool man said it was not Can you give me any ide of what it might be the system was installed in 1964 and even though old still works perfectly whith this one exception. Thank you - Carol 8/15/11
Question: bad sewer smell early in the morning - landlord says system needs to be broken in
We moved into a doublewide in western NC last March. We noticed, mostly late evenings and early mornings, a really bad sewer smell. Our landlords said that sometimes, as a system gets used to new people and new system uses, it can be a little smelly. Anyway, soon, spring and then summer arrived and the smell had gone away completely. At the very first sign of fall, however, the smell has returned. Now that all of our nights are in the 40's or below, we are smelling it again every morning and evening, but not during the heat of the day when temps reach the 70's. There is no smell coming from inside the house, only what drifts in through open windows. Everything seems to drain fine in the house. Totally clueless and really frustrated at this point. - Jeff 10/6/11
Question: smell in unfinished bathroom
I hope that some help be given as we are at our wits end. I have and unfinished bathroom in the basement
Question: sewer odors coming out of interior perimeter drain in dry basement
Ok I have an issue... I own a bi-level home. One of the bedrooms is in the lower level. The entire lower level is finished. There is a french drain that run around the entire basement, however most of it is covered. There is no water, nor has there ever been any water in the drain. Over the past week, out of the blue the odor that is coming from the drain is mind blowing. It smells like ammonia and other things. The room that smells is closest to the septic tank. Thinking that there might be a problem I had the tank emptied and still no releif from the smell... When it rains the smell only gets worse... Any suggestions on what I might be looking at. - Brian D 11/29/11
Brian, on occasion I've found that a leak in the sewer line or even at the tank itself it it's near the house can leak into the foundation drain or perimeter drain and even enter the basement. As you've not seen a problem at the tank itself I'd check the condition of the sewer line between the house and the septic tank next.
Question: raw sewage odors in very cold weather
I read your article and I would like to explain my problem to see if I have come up with the problem. I live in Cheyenne Wyoming and when it is very cold (below 25 degrees Far.) we get a very strong raw sewage odor from our basement bathroom. I have narrowed it down to the bathtub. We did not finish the basment, it was finished when we moved in. The odor was not disclosed to us when we moved in 3 years ago and this winter it is worse but it is colder. We have smelled it every winter since we moved in. Now tonight I decided to try an experiment. I closed the drain on the tub and put water in the tub and this seemed to fix the problem. So my opinion is that they did not put a "P" trap on the tub. So what do you think?
There may be a corroded leaky P-trap that thus doesn't maintain its water seal. Try pouring water into the trap and inspect with a good light to see if it remains in the drain; Unfortuately some demo and digging may be in order to fix this odor source.
Question: septic tank under the garage
OUR SEPTIC TANK IS LOCATED UNDER OUR GARAGE WE HAVE A SEALED HOLE WITH A CAP ON IT DURING THE COLD MONTHS WE GET A SEWER SMELL IN SPECIFICALLY ONE PART OF OUR BATHROOM ITS THE AREA WHERE ALL THE PIPES ARE LOCATED THE TOILET SHOWER AND SINK WATER ALL GO INTO THE SEPTIC TANK WE TORE UP OUR FLOOR AND REPLACED ALL THE PIPES WE HAD OUR TANK CHECKED ITS WORKING FINE NOT MUCH IN IT BUT AS SOON AS IT GOT COLD IT STARTED TO SMELL DO YOU HAVE ANY IDEAS WHAT WE COULD DO - Cheri 1/14/12
oh why do people type in all caps.
A septic tank under a garage floor sounds like a bad idea to start with - but in any case if it smells the system may be backing up; check for drainfield flooding;
Watch out: accumlated sewer gases indoors (in your garage) can cause an explosion or can be an asphyxiation hazard - i.e. fatal
Question: septic works but smells when it's cold and damp outside
I have a septic system that works fine, however I have an unpleasant odor...usually when its cold and/or damp outside. I originally had a single wide mobile home then moved it out and put in a double wide....thats when the problems started. I've tried everything with no luck. I've tried suggestions from plumbers, had plumbers out and no one can narrow down what the problem is.
When the double wide was installed the plumber put in a clean out trap....could that be part of the problem? I had the tank pumped in the summer and it seemed to help....but not get rid of the problem. I'm now trying to sell my house, but can't sell til this issue is resolved. Please can you offer any suggestions for me.?
When you changed your mobile home, is it possible that someone drove across and crushed a septic drain line or damaged the drainfield?
Question: sewer gases when weather turns cool
After a change in weather to cooler temperatures, we are smelling sewer gas which we believe are coming from both bathrooms. My husband says the bathrooms are on separate ends of the house. The smell of gas is throughout the house. - Gail Gilbert 9/10/12
Gail, check the odor track down suggestions above
Question: odors from mobile home worse when furnace is running
My furnace in my mobile home sits in front of a lot of my plumbing in the bathroom. i believe because as the weather gets colder, we use the furnace, and then thats when it smells the worst. i have also noticed that while the furnace is running and then run water in the kitchen, its the worst! - Anon 10/31/12
Look for a blocked or missing plumbing vent that is causing drain gases to back up out of a drain near the furnace return air intake
Question: sewer smells near washer during heavy rain
Last may I installed a washer in the basement. Everything has been fine until we had over 6 inches of rain during a 24 hour period back in September - at that time, I noticed a septic odor in the basement and also in the cabin. Since then, the odor has appeared during cold damp weather, but only in the basement. I don't smell anything outside, just in the basement. My tank was cleaned out four years ago and I live alone, so I would think the tank is fine. Before calling the septic service and spending money I don't have to spare, I would appreciate your opinion and suggestions. - Diane 10/31/12
Check our suggestions about bad plumbing vents as well as flooding septic systems in the sewer gas odor article links found at page top
Question: sewer gases picked up by furnace during cool weather
Now that the weather has turned cooler and the furnace is on, we are experience sewer smells thru the heating floor vents on the upper levels of the house. We also have smelled the same odor from the drain in the basement bathtub. There was no odor throughout the summer or spring months. Can't figure it out so far. - Deborah 11/17/12
Reply: check for sewer gas draw into cold air returns; try using a sniffer person or a TIF8800 combustible gas detector
Deborah, if sewer gas odors come out of heating supply registers I suspect that sewer gas is being drawn in at a cold air return. That may help you start looking.
Last winter we had $10,000 worth of drain work done to replace the old clay ones under out house. They put in all new clean outs to meet regulations. This was done in December and we survived the winter season without any problem with sewage smells, although it was fairly mild. Prior to this work being done our daughter lived in the basement for at least 10 years without problem.
We called the drainage company who did the work back and he checked all the drains for P traps and dry/wetness. He claimed all was fine. Could it be the old city pipes coming into our new connection that might be a problem? Thanks for any and all help. We are in the process of getting someone to climb our roof to check the stack for some kind of animal blockage (nest) perhaps. It's driving us crazy. The contractor said to call him back if the smell still persists which we will do. - Deborah 12/5/12
Questions & answers or comments about diagnosing the source of septic or sewer odors in cold weather
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