Aerobic septic system odor problem diagnosis:

This article series discusses problems that occur in aerobic septic systems, also known as aeration septic systems or fine-bubble septic aerators. We identify things that cause problems with or harm aerobic septic systems.

Odor & Smell Complaints at an Aerobic Septic System ATU

9 Steps to Diagnose & Fix Aerobic Septic System Smells

Start diagnosing the cause of aerobic septic system odors by following these steps

1. Check that the aerator pump is running
   
   and if your system is not designed to run the aerator pump continuously, check the timer settings and review those with the aerobic septic manufacturer of your system
   
   Watch out: the most-common cause of abnormal odors or smells from aerobic septic treatment units or ATUs is insufficient oxygen in the septic treatment tanks.
   
   That in turn can be caused by any problem with the aerobic septic system's aerator pump or distribution tubing: a failed pump, improper aerobic pump timer settings, disconnected, leaky or kinked aerator tubing tubing, or a clogged air outlet in the septic tank.
   
   See details at AEROBIC SEPTIC AERATOR PUMP PROBLEMS
2. Check the aerator pump tubing
   
   for kinks and leaks
3. Check the diffuser in the septic tank
   
   to be sure it is not clogged - this check should be performed at least once a year
4. Determine the time & conditions under which odors appear:
   
   if the system has smelled since installation there may be an installation or operation-set-up error; if the aerobic system smells only in wet weather there may be a flooding or effluent distribution failure
5. Review the septic system loading
   
   in gallons of wastewater per day versus its design. A surge of wastewater caused by multiple guests or many loads of laundry may be overloading your aerobic septic treatment unit.
   
   If your aerobic septic treatment unit is overloaded by wastewater volume it may be unable to aerate the sewage enough to prevent odors.
   
   See details at AEROBIC SEPTIC OVERLOADING
   
   Check for subtle septic overload sources such as a running toilet.
   
   See TOILET RUNS CONTINUOUSLY
6. Check the location at which septic odors are most-apparent:
   
   Septic odors apparent indoors?
   
   Odors in the bathroom may be due to a plumbing vent defect (dry drain traps) or caused by leaks at a toilet base.
   
   Odors at a sewage ejector pump could be from a leak, improper vent, a bad check valve. Those are not aerobic treatment unit defects.
   
   We provide a complete list of causes & cures for plumbing system odors starting
   
   at PLUMBING SYSTEM ODORS - home
   
   Septic odors most-apparent outdoors? let's be more-accurate.
   
   Odors wafting down from a rooftop plumbing vent may be a result of site conditions, roof height, slope, wind direction, nearby trees, etc. or the odor may indicate that treatment in the septic system is inadequate and that odors are back-venting up through the building vent system.
   
   Extending the plumbing vent height, adding a rotating top that keeps the vent facing down-wind, or adding a carbon filter may help,
   
   Watch out: adding an odor filter to a rooftop plumbing vent can cause slow fixture draining and even loss of the water seal in sink, tub, shower traps if the filter blocks adequate air movement in the vent system.
   
   Odors around the septic tank, if intermittent and mild, may be normal for your septic system. But if odors are constant and strong, check for a leak at the septic tank cover and its access openings. Aerobic septic tanks and tanks that use an effluent distribution or removal pump will usually have a bolted-on plastic access lid whose seal may need replacement.
   
   Watch out: leaks at a septic tank over may also permit ground-water entry that can flood and damage any septic systems.
   
   While you're inspecting the septic tank cover and access openings be sure that they are strong, sound, and secure against removal by a child or against someone falling into the septic tank.
   
   Details are at SEPTIC & CESSPOOL SAFETY
   
   Odors over the effluent distribution field or drainfield, particularly if strong and constant, may indicate that the level of treatment in the aerobic tank is inadequate. Go back to steps 1 - 5 above.
   
   A failed septic field due to flooding or soil-clogging will need repair or replacement. Repair could be as limited as finding and fixing a broken pipe or as extensive as complete field replacement.
   
   Details are at SEPTIC DRAINFIELD FAILURE DIAGNOSIS
   
   
7. Does your aerobic septic system require chemicals or a disinfection step?
   
   Some septic system manufacturers specify regular use of an additive or disinfectant. Check with your septic system manufacturer.
   
   Watch out: if septic treatment or disinfection are not specified by your system's manufacturer, do not rely on "treatments" to cure septic system odors.
   
   Most septic systems do not require septic system treatment or additive chemicals or products and in fact some of those products (for example harsh chemicals or yeast) are harmful to the septic system and some are prohibited by your state or provincial codes.
   
   See details at CHEMICALS & TREATMENTS for SEPTICS
8. Other causes of septic system odors
   
   include effluent distribution failure or leaks or septic disposal field flooding.
   
   See SEPTIC SYSTEM ODOR CURES - our home page for causes & cures of odors from septic systems
9. Other cures for septic system odors:
   
   See REMEDIES for SEPTIC SYSTEM ODORS

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Question: my sewer smells really bad, it was pumped, I put in new yeast and chlorine, and my air pump is running

My sewer smell really bad i have had it pump out about 1 1/2 years ago new yeast chorine and my air pump is working what can i do - Mark 1/23/12

Reply:

Mark, yeast is not a normal septic system. I would contact the manufacturer of your system and ask for their advice and for a copy of the instruction manual.

According to some expert sources [3] a slight odour from an aerobic septic system is normal but strong, persistent odors indicate that the system is not working normally.

I agree that a strong odor problem is unacceptable, not normal, and can be corrected.

Question:

(Aug 10, 2015) Sandy MacDonald said:
What can be done about fairly strong odors coming from an ATU system. Are chlorine tablets recommended? Any suggestion would be appreciated

Reply:

Sandy

You need an aerobic septic system service company to take a look at your system. I would not amend the normal disinfection treatment specified for your particular system design before determining what's the actual problem. More speculation on my part, with no data about your system, would be mere arm-waving. Do keep us posted as we may be able to comment on what you're told or to suggest things to ask.

Other than an occasional mild odor right at the ATU, the system should not be stinking up the yard.

 

On 2020-12-23 by (mod) - Aerobic septic odor complaint

Has anyone confirmed that the aerator is properly installed and working correctly?

About running the aerator only part time rather than full time you might want to check with the manufacturer to be sure they think that's a reasonable step and that it won't interfere with the effectiveness of the treatment.

Some aerobic systems expect the aerator to run full time and may fail otherwise.

On 2020-12-22 by Alyssa

I have a Cajun Aire aerator. A few months ago, we noticed a very strong odor when it was running. Our septic company has been out multiple times in the past few weeks attempting to figure out why there is such a strong smell.

The company suggested we put it on a timer, which we have, so it's only running at night so we avoid the smell during the day. The septic company vented our septic system years ago as well. Neither we nor the company can figure out why the smell is starting now, after 16 years.

On 2020-06-04 by (mod) - diagnose and fix aerobic septic odors that occur after showering or running the washing machine

Ben: if your wastewater volume exceeds the daily limit designed into your particular aerobic septic treatment unit then the system may not be able to provide sufficient aeration and oxygen to speed the breakdown of sewage in the aerobic treatment unit tank.

The result can be odors near the septic tank or in the disposal field.

Some aerobic manufacturers specifically recommend limiting the number of washing machine loads you run per day, but of course there are also high efficiency clothes washers and dishwashers as well as low-flow toilets and shower and faucet heads, all of which can make a big reduction in your daily wastewater volume - another approach to solving the ATU odor problem.

Check with your specific aerobic septic manufacturer about the daily wastewater volume that your ATU can handle, and then estimate your actual daily wastewater flow for comparison.

WATER QUANTITY USAGE TABLES may help you make that comparison.

Also double check that you're not un-knowingly overloading your aerobic septic by a less -obvious cause such as a running toilet.

Finally: see if you can track the odor to a specific fixture drain: inadequate plumbing vents or clogged vents can cause loss of the water seal in a plumbing trap - another cause of sewage odors indoors.

See details at PLUMBING VENT BLOCKAGE ODORS

On 2020-06-04 by Ben

I get a slight odor in the house and sometimes it gets stronger after taking a shower or running the washer Machine

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Continue reading  at AEROBIC ATU SEPTIC PROBLEMS - home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• AEROBIC SEPTIC SYSTEMS, ATUs - home page for Aerobic Septic Systems
• AEROBIC SEPTIC SYSTEM ATU SUPPLIERS & MANUALS
• AEROBIC ATU SEPTIC PROBLEMS
  • DONT FLUSH DRUGS & DISINFECTANTS
  • AEROBIC SEPTIC AERATOR PUMP PROBLEMS
  • AEROBIC SEPTIC ALARM SYSTEMS - how to silence & troubleshoot
  • AEROBIC SEPTIC EFFLUENT SPRAY HEAD REPAIR
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  • AEROBIC SEPTIC LIFE EXPECTANCY
  • AEROBIC SEPTIC MAINTENANCE: Clearstream ATUs
  • AEROBIC SEPTIC MAINTENANCE PROCEDURES
  • AEROBIC SEPTIC ODORS & SMELLS
  • AEROBIC SEPTIC OVERLOADING
  • AEROBIC SEPTIC PIPING & BLOCKAGES
  • AEROBIC SEPTIC SALT IMPACT on
  • AEROBIC SEPTIC WINTERIZING
  • FROZEN AEROBIC SEPTIC or WATER SUPPLY SYSTEM
  • HOOT AEROBIC SEPTIC TROUBLESHOOTING
• AEROBIC ATU SEPTIC MAINTENANCE PROCEDURES
• SEPTIC SYSTEM ODOR CURES

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INDEX to RELATED ARTICLES: ARTICLE INDEX to SEPTIC SYSTEMS

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