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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 sewer or septic odor troubleshooting: this article series discusses the diagnosis and correction of sewer gas or septic odors (and other building smells and odors with focus on diagnosing odor sources and causes in cold weather.
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. Also see METHANE GAS SOURCES and see our broad-scope article on diagnosis and cure of sewer gas and septic odors: SEWER GAS ODORSdiagnosing, finding, and curing septic tank and sewer line smells. For more general guides see ODORS & SMELLS DIAGNOSIS & CURE for procedures to diagnose and cure all kinds of odors in and around buildings.
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.
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 Drain Noises: may indicate defective or clogged plumbing: how to diagnose and cure drain sounds
Cold Weather and Plumbing Vent Blockage Problems as a Source of Building Smells, Septic or Sewage Odors
What's different in cold weather that could cause indoor sewer gas odors only during freezing weather?
If in cold weather a plumbing vent pipe is frosting up, sewer gases may vent backwards out through building drains. In that case, even re-priming building drain traps won't prevent sewer gas entry as flushing a toilet or running a nearby drain can siphon water out of a nearby trap.
A thoughtful reader, Jill Elwert, suggested insulating the vent piping to try to delay vent pipe blockage by freezing moisture. We are afraid that even if you insulate the vent line in a cold attic, it'll freeze above the roof surface outdoors. You could try it but if that proves the problem, ultimately you'll want to have a plumber or handyman install a 2" or larger diameter vent from the attic floor up through the roof. See Remedies for Sewer Odors.
Diagnosing frozen plumbing vent lines:
See Plumbing Vent Defects for diagnostic details.
Freezing weather can cause a complete blockage of a plumbing vent stack by frost. For example steam from long showers moves up the vent pipe where it freezes in the pipe section extending above the building roof.
The absence of venting (missing or blocked) causes plumbing trap siphonage and loss of water in building traps. (Water flowing down a drain line without a nearby supply of makeup air to follow the water creates a vacuum that pulls water out of nearby plumbing traps. Flushing a toilet can siphon out a nearby sink or tub trap.)
What happens when the water seal is lost from a plumbing trap?
When the water seal is lost from a plumbing trap sewer gases can back up out of that fixture and not just smell bad. Sewer gases contain methane which is an explosive gas - possibly quite dangerous. In addition to occasional methane gas explosions inside buildings, I've had a report of an outdoor septic tank explosion too when an owner built a brush fire atop the tank.
In sum, dry plumbing traps are caused by evaporation at an unused fixture, leaks at the trap, or siphonage due to improper plumbing vent line installation. Dry traps can leak smelly or dangerous sewer gases into a building.
Check for dry plumbing traps, particularly at un-used basement or lower floor fixtures and at floor drains which might be connected to the sewer line. "Dry trap" means that there is no water in the trap bend or weir.
Frequently Asked Questions (FAQs)
Questions & answers or comments about troubleshooting and fixing septic or sewer odors in and around buildings when the odors appear mostly in wet or cold weather.
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Technical Reviewers & References
Use links just below at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.
Diagnosing Sewer Odors - see detailed links at page top & left
Design Manuals for Septic Systems
Onsite Wastewater Disposal Books