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Odors from Septic Tanks

Odor from the tank of a septic system; an ongoing status report of my solution to one type of septic tank odor problem.  To clarify my septic odor solution report, I have moved the status update information to this page, removing clutter from the original page.  Please click here, septic odor solution, for the original article.  I will post any new status information here about my efforts to reduce septic tank odors occurring in my yard or on my property in general.

Septic Tank Odor references

Montana State University.
Septic Tank and Drainfield Operation and Maintenance, from the MSU Extension Service
University of Maryland
Septic Systems Maintenance

Septic Tank Odor statuses

(10/02/2005) Septic tank pump out

We had our septic tank pumped.  No, at this time there was no odor from the tank, or system, or any problems.

We have a sand mound system.  This means you will usually have a tank at the sand mound and one near your house.  And the tank near our house had two chambers!  We have lived in the house 3 years and had used it as a vacation home for 2 years before that.  I do not want any problems, ever, in the winter so I was very conservative with this first pumping.  Both tanks and the two chambers were pumped at a cost of $250.  $20 discount since I helped with the digging!  We had to dig about a foot down to the two chambers near the house.  Topsoil and stone had been piled on top of the chamber plugs (1.5 foot round concrete plugs).

The tank near the sand mound was pumped first.  This tank has a simple manhole access.  There was probably about 2 inches of sludge.  This meant there was 6 inches of head room remaining.  So conceivably we could go 3 * 4 years without a pumping of this tank.  And in fact the fellow that did the pumping said maybe only do the lower tank every other pumping of the upper tanks.  The electric pump in this lower tank is mounted about 8 inches above the bottom of the tank.  The pump is there to force the water into the sand mound piping and distribution system.  This tank is as big as the tank at the house, 1000 gallon, but normally only 8 inches is used.  If the pump fails an alarm will sound in the house.  The tank does provide a large buffer volume for water should the pump fail.

Septic Odor Filters


Septic Odor

Wolverine Vent Filter

The wolvering vent filter

Residential & Industrial Odor Control


The upper tanks were in good shape also.  You could see the outline of the septic tank in the grass.  Even though the tank is a foot down I am guessing the concrete still affects the soil ph (acidity/alkalinity), perhaps retarding the grass growth.  The upper tanks had more sludge and scum.  Surprisingly there was not much odor, no toilet paper build up either.  If there is a lot of undigested material (toilet paper) perhaps you have used too much chlorine bleach or other harsh chemicals.  The fellow who pumped my tank did not seem very concerned about feminine products either.

We opened one chamber and pumped it dry first.  I noticed backflow at what should have been the outlet of the tank, making me believe there was a second chamber.  And unfortunately for us that meant digging a second hole one foot down to the second chamber.  The concrete plugs usually have two loops of steel rebar, and we had two hooks to pull the plug.  The plug had no wax sealer as I have read about in the past Both chambers had a good bit of sludge and scum, but there was also plenty of capacity left.  I can easily go five years between pumpings, it appears.  This is comfortable to know and one reason to pay to have the tank pumped after 3 years of actual use.  The entire pump out process probably took 3 hours, I did the backfill later.

I back filled the two holes removing all stone to facilitate the next pump out and digging.  I came up slightly short of topsoil.  Even with a foot of dirt I could see after the first rain, water may have leached through the soil and into one of the chambers.  This is not good, and is why they probably do use wax seals on the septic tank plugs.  I added a little more topsoil to make sure there was no potential for water to pool above the tank area.

One big problem for us is soft soil, many years our field where the lower tank is located is very soft and would not support the pumper truck.  This year was dry and the truck had no problem.  Yet another reason for this conservative pump out.  All to avoid odors and problems from the tanks in the septic system!

(2/22/2009) Pipes are still in place after many very high winds.  In most cases odors are reduced, but unfortunately not always gone.

(4/27/2005) We do have occasional odors on days where the air is stagnant.  Always when we get up, just after showers, etc, anytime you put a substantial amount of the water into the system.  I have been forgetting the Baking Soda.  Remember baking soda is just sodium bicarbonate, your local swimming pool supplier will carry it in tubs as "Alkalinity Up".  The large baking soda boxes in the super market may still be cheaper, but a large tub is sure more convenient for regular, weekly, application. 

Septic Tank Odor, Vents on the house(10/20/2004) The A & H septic care documents are back in Word format!  Here is a link to an Arm & Hammer Microsoft Word Doc file with the complete information regarding a partial septic odor preventative:
A & H septic.doc  NO Sorry gone again 02/08/2013

(10/18/04) Continuing success with the 4 ft extensions!  This in conjunction with my wasp reduction effort has made our deck a much more pleasant place to be.  I continue to add the two additives.

(6/27/04) The four foot extensions seem to be doing quite well.  They just clear the roof line of the house.  We have had no problem with septic system odors with these extensions.  I continue to add baking soda weekly.

Septic Odor Filters

Septic Odor

Wolverine Vent Filter

Septic vent filter

Residential & Industrial Odor Control


(10/27/03) Since I have written this article I have had some very high winds with no problems for the five foot pipe extensions.  However I am shortening the pipes to 4 feet for aesthetics.  I will report back about how 4 feet extensions do next spring and summer.

(10/27/03)  I now have been using a cup of baking soda on a weekly basis for several months. I flush it down the toilet.  There was a period when I had the pipe extensions off and during this period while I still smelled septic system odors they did seem reduced, a subjective conclusion but I will still continue the baking soda.  But, it is weird when you think about it, that a manufacturer has convinced me to buy their product and flush it down the toilet!  As above I will be sticking with 4 foot vent pipe extensions.








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BHT Revised: 22 Oct 2016


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