Question? Just ask us!
Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair
InspectAPedia ® Home
ODORS GASES SMELLS, DIAGNOSIS & CURE
AIR POLLUTANTS, COMMON INDOOR
AIR QUALITY IMPROVEMENT STRATEGIES
ALLERGEN TESTS for BUILDINGS
ANIMAL or URINE ODOR SOURCE DETECTION
BACKDRAFTING HEATING EQUIPMENT AQ
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
DRYWALL MOLD TESTING
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
GAS 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 MOLD / ODOR TREATMENT WARNINGS
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
VOCs VOLATILE ORGANIC COMPOUNDS
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
This sewer gas smell article describes how to get rid of or cure odors in buildings including septic or sewage or sewer gas smells or "gas odors" in buildings with a focus on homes with a private onsite septic tank but including tips for owners whose home is connected to a sewer system as well.
Citation of this article by reference to this website and brief quotation for the sole purpose of review are permitted. Use of this information at other websites, in books or pamphlets for sale is reserved to the author.
Green links show where you are. © Copyright 2014 InspectApedia.com, All Rights Reserved.
In a properly constructed drain-waste-vent system and septic tank installation, sewer gases produced in the septic tank find their easiest escape path back up through the scum layer and into the septic tank inlet tee and from there up the drain waste vent (DWV) system to the building plumbing vent stack system where gases are vented above the building roof.
More septic or sewer gases may escape and make their way through the tank's outlet tee top into the soil absorption system where the gases are distributed over a larger (leachfield) area and further filtered and deodorized by the soil.
Where a building is connected to a municipal sewer, the building drain-waste-vent system (DWV) includes traps and vents to be sure that any sewer gases passing back up waste lines are vented safely above the building roof.
Watch out: as we warn in all of our sewer gas articles, because sewer gas contains methane gas (CH4) there is a risk of an explosion hazard or even fatal asphyxiation. Sewer gases also probably contain hydrogen sulfide gas (H2S) In addition some writers opine that there are possible health hazards from sewer gas exposure, such as a bacterial infection of the sinuses (which can occur due to any sinus irritation).
Depending on the sewer gas source and other factors such as humidity and building and weather conditions, mold spores may also be present in sewer gases.
Also see Wet Weather or Cold Weather Septic Odors or Sewage Odor Diagnosis & Repair Guide for additional odor tracing and cure advice for odors occurring during wet or cold weather.
A variety of mistakes or just plain bad luck about site terrain shape and prevailing wind, or something more serious like a failing septic system can, however, produce sewer odors at a property.
Here are some steps to diagnose and correct gas odors at properties served by septic systems. Some of these steps also apply to homes connected to a municipal sewer as well.
What Gases Form in the Septic Tank
At SEPTIC & CESSPOOL SAFETY we've already explained that gases produced in a septic tank are dangerous, as a potential source of explosion and as a cause of death by asphyxiation if someone falls into or deliberately enters a septic tank.
The gases that form in septic tanks are primarily two, methane, CH4, and hydrogen sulfide H2S. It's the H2S (a "rotten egg" smell) that people mostly notice if gases from a sewage system are not properly vented at a building. Other gases produced by the decaying organic matter in the tank are also mixed into this brew as well.
Septic Tank Gas Leak Points Outside
Experts [Burks/Minnis, Kahn et als, Jantrania] will tell readers that septic tanks and their covers and access covers and piping fittings should all be sealed air-tight with proper rubber gaskets.
In nearly 50 years of looking at septic tanks and systems, I've rarely seen a conventional concrete tank which was sealed with gaskets.
Some steel and certainly some of the newer fiberglass septic tanks may be in fact more precisely designed and built, but concrete septic tanks and covers are a bit rough and will be leaky in most installations.
Septic Tank Acidity can Cause Odors
Acidic Septic Tank Problems can also cause odors: See Acidic septic tanks
Septic System Maintenance vs Septic Odors: sewer gas, sulphur odors, rotten egg smells
A review of septic system maintenance advice, particularly from aerobic treatment unit or ATU septic designs makes clear that a system that is not properly maintained may be a source of troubling smells, while a properly operating and maintainted system is not normally a source of complaints. Some examples of septic system maintenance snafus that can result in sewer gas odors at the site or backing up into the building include at least these:
Septic Tank Gases Back Up Into Building
Sewer gases formed in the septic tank can return to a building interior by backing up from the septic tank inlet baffle and pipe to the building drain-waste-vent piping. Inside the building sewer gas (rotten egg or methane) smells may be observed:
Continue reading at SEPTIC / SEWER ODOR SOURCE TABLE or select a topic from the More Reading links shown below.
Suggested citation for this web page
Green link shows where you are in this article series.
Frequently Asked Questions (FAQs)
Question: rotten egg sulfur smell from septic system while aerator is off
My septic has an aerator and pumps that move water to an above ground sand pit. The aerator has been off while I wait on a pump float repair. Been a few weeks.When I turn on the pump manually(float broke) I noticed the sulfur smell today.Water never smelled great,but the sulfur is much more intense now.
Can I flush something to lessen the stink,or just run the aerator manually too? I had the aerator off because the back up in water due to broken pump makes the aerator alarm go off.That switch is outside.
This is a newer 2005 singular septic.County required it.Now they require UV light systems.I miss the septics with NO electrical hook ups.Thank you for any suggestions. E.W. 1/1/2014
I don't have a full understanding of the design and operation of your septic system, but can offer these general comments: I would hesitate to add typical chemicals or additives used for sulphur odors to a septic system as you risk killing off bacteria; and it is not normally necessary nor even useful, and in some jurisdictions illegal to use septic system additives or treatments. You might reduce odors by running the aereator manually as you suggest.
If by "singular septic" you are referring to an aerobic system designed and sold by Norweco / Singulair - www.norweco.com then you might contact the company for other suggestions. You can also contact the company at 800-NORWECO, Norwalk Wastewater Equipment Company, Inc. 220 Republic Street Norwalk, Ohio U.S.A. 44857-1196 Phone: (419) 668-4471
It is not a good idea to leave the aerator of an aerobic septic treatment system off for weeks or longer. The risk is not only the discharge of inadequately treated effluent and thus environmental contamination, but possibly system clogging and failiure. I'd want to get that pump going with proper repair parts promptly or if that is not easy, then to ask the manufacturer for suggestions for a substitute pump or part that can be used.
Details about aerobic septic system maintenance, treatments, chemicals and suppliers are
(Sept 14, 2012) jennifer said:
i just moved into a house i am renting, and the smell from the upstairs bathroom when you drain the tube water and the most horrific rotten egg smell comes up too. i have 5 children and i brought it up to my landlord and she said there is nothing she can do. please help tell me what to do thank you.
If the water supply is not itself smelly then I don't suspect sulphur in the water but instead a sewer gas problem, perhaps due to a blocked drain or improper or inadequate venting. Inadequate or malfunctioning sewer drain venting is unsafe, risking both methane gas leak explosions and potentially gas exposure or pathogen hazards. I'd ask the landlord, in writing, to address the concern as one of health and safety.
(Dec 19, 2012) Jim said:
I have a walkout home with a septic system. To get rid of grey water and sewage from the basement there is a lift pump.When the lift pushes the waste out to the septic system it sucks the water out of the trap at the upstairs bathtub. It doesn't affect the kitchen sink or any other fixtures. I believe that the venting through the roof is probably to small. I was told by another person that I should install a "Air admittance valve" in my system. Would I install this at the lift in the basement or at the bathtub? If it goes on the line to the bathtub would it go downstream of the trap? Thanks for any help! Jim
(Feb 9, 2013) joe said:
hello i have an overactive sewer smell coming from the roof vent on the roof; not all the time. it's an in-ground septic system. will extending the vent a couple of feet higher help? thanks
9/19/2014 Brent said:
I live in a home that is on pier & beam foundation. Recently we had a sewer line break that we were unaware of for about a week. It was repaired but naturally very damp. I put a strong fan under the house to dry out the soil. It has been about a week and we re now getting a smell in the house naturally the reeks of dried sewage. What can I do to rid of the smell?
Unfortunately you'll need to remove contaminated soil, possibly treat what remains with a sanitizer or disinfectant, and you may need to add a plastic ground cover as well.
Comment-Opinion: recommends filters atop plumbing vents
(Mar 7, 2013) Rod Pennington said:
The well known rain storm term "it was a gully washer" comes from the fact that sewer vent pipes all used to exist at ground level by design. Because of odors the "gully vent" was moved to the roof in the US and worldwide almost a century ago. Moving them to the roof allowed the wind to dissapate some of the smell, but they still stink, now refered to using a newer plumbing term "stink to high heaven." The only way to "Stop the Stink," is by using a vent stack filter. Initially these filters were simple activated carbon, but because activated carbon allows a pugging type of slime growth newer carbons such as Zeocarbon and Chemically treated carbon to prevent growth are now more effective
Thanks for the comment Rod.
Watch out: adding filters atop a plumbing vent may risk vent clogging and thus poor drain performance or sewer gas entry into a building.
Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.
Search the InspectApedia website
HTML Comment Box is loading comments...
Technical Reviewers & References