BHT Revised: 09 Sep 2013

Septic system odor tip

A simple tip to help with septic system odor.  My home is in a location where the normal breezes tend to swoop over the roof of the house.  This seems to act like a wing or airfoil and draw the air that flows over the house down and into my deck and backyard area.  I believe these septic system odors are normal in our case.  If the wind is striking the front of my home I smell the septic tank odor in back, likewise with the wind hitting the back I get septic system odor in front, but this only seems to be a problem when special wind conditions are present and someone is using the bathroom or taking a shower, anything that forces water through the septic system.  Obviously for a short period of time, adding water to the system will cause septic system smell to be forced up the vent pipes and with the right winds down onto our deck.

When they install chimneys they make sure that the stack is sufficiently high that the smoke will be carried away by the wind regardless of its direction.  However if you look at the waste and septic system vent pipes coming out of the roof of your home you will see they only typically extend about 1 1/2 feet above your roof, perhaps less!  My septic tank vents are even shorter.  If the wind is flowing over your home it just carries the septic system odors right down into your yard with it.

Septic System Odor solution 

Noting all this I put 2 1/2 foot PVC extensions on all four of my septic system vent pipes.  These pipes are typically 3 inch PVC pipes and it is very easy to get an extender and more 3 inch pipe at your local building supplier.  This pipe is very easy to cut with a hack saw, table saw, or circular saw.   I did not fasten or cement these septic system vent pipes in place in any way, just a press fit.  The 2 1/2 foot extensions have been up for 3/4's of year through very high winds without a problem.

The 2 1/2 foot pipe did help, but still there was frequent septic smell. So I looked at how high my chimney stack was and decided to try five foot extensions, replacing the 2 1/2 foot extensions.  This made a big improvement, reducing the septic system odors substantially, but, it is not very pretty!  Also I am concerned that a five foot extension may be just a little too long in high winds.
This is a shot of the house with 4, 5 foot extensions.  As you can see the extensions now reach above the roof line, but still are not quite as high as the chimney stack.  I think I can get away with cutting these down to 4 foot extensions, improving the appearance but still getting the benefits of sufficient height so septic system odors are not drawn down, but away from the house.  I have also capped one pipe with a vented cap to solve a plumbing error discovered after construction.

Very infrequently (twice in 3 years) I would get septic system odors in my basement, this could be dangerous!  I had learned early on that the builder of my home had made a mistake.  I had asked for provisions for a bathroom in one corner of my basement, but I believe the builder of my manufactured home provided a spare vent pipe, but it was in the wrong location for the bathroom. So I have an open pipe from the basement to a header in the attic  where several septic system vent pipes are joined to one vent on the roof.  With just the right wind conditions, septic system smell that should have exited through the roof vent, actually down drafted into the basement.  So I had septic system odors in my basement.  I have plugged the pipe for now, but condensation forms in this pipe and does accumulate at the bottom, another problem to solve!

Sensible Septic Tank care and septic system odor problems

I am also going to try the Arm & Hammer suggestions in their "Sensible Septic Tank care" document.  Their discussion seems sound, a quote (from a page I cannot find anymore!):

"Also, at this pH level, hydrogen sulfide is fixed in solution so that it cannot escape as an offensive gas. This greatly reduces the characteristic septic smell escaping from the drainage field in the lawn or from the vent in the roof. "

Here is a link to an Arm & Hammer Microsoft Word Doc file with the complete information:
....armhammer.com/brochure/documents/septic.doc

Sorry even the above document is gone!  Below is all that is left:

Flush our product down your toilet!

Please see the page above for more document links:
! BobsHowTo.com - Do It Yourself Tips and Tricks !

Septic System Odor, pipe extension findings.

I have move the ongoing status reports to my Septic tank odor status page.

Septic system smell and additives

I have and am still using a septic system additive product (biological).  I found this product had no impact on my septic system odors.  I will continue to use this product until I run out of it and then I will probably never use an additive other than baking soda.  It does not seem there is enough evidence to justify the cost of these products.

So if you have odor from your septic system, longer vent pipes do help significantly, I hope they will in your case.  If you still have problems I would suggest trying the Activated Charcoal filters.  I have not tried them personally, but they certainly look promising for septic system odors;  Activated Charcoal Filters.

I hope these septic system odor tips help.

Thanks,
Bob

Some additional information

The Soap and Detergent Association home page.  They provide information regarding antibacterial and antimicrobial agents and their impact on your septic system and septic system odors.  It appears they have some research to back up their statements.
The Soap And Detergent Association

The abstract of one of the papers the SDA references from the ETC Environmental Toxicology and Chemistry society
FATE OF ADSORBABLE ORGANIC HALIDES FROM BLEACHED LAUNDERING IN SEPTIC TANK SYSTEMS

Worried about detergents look up "linear alkylbenzene sulfonate (LAS)", we septic owners seem to be lucky!  Those little bacteria just about eat anything.
CLER Fact Sheet LAS BIODEGRADATION AND SAFETY