How & why to convert a septic tank and drainfield system to an aerobic septic system:

What is required to convert a conventional septic tank and soakbed system to an aerobic treatment system or ATU? Is it possible to change over a regular septic tank and drainfield to an aerobic treatment unit design?

Will that cure a failed drainfield? Will that conversion work better, use less space, better dispose of wastewater? What about aerobic septic conversion costs and aerobic system operating costs?

Convert from a Conventional Anaerobic Septic System (tank and drainfield) to an Aerobic ATU Septic System Design

Why Convert from Conventional Septic Tank to an Aerobic System

Converting a traditional septic tank and leachfield to an aerobic septic system improves the level of wastewater treatment, reduces the risk of contaminating the environment, wells, lakes, streams and neighbours with sewage pathogens, and it might permit on-surface discharge of highly-treated septic wastewater effluent if that is permitted where you live.

[Click to enlarge any image]

You'll read in some of the reader questions later in this article that some folks are fooled into thinking that increasing the level of treatment of their septic wastewater will repair a failed septic soakbed or drainfield. It won't.

Our sketch shown at left illustrates two conventional septic tanks - a single chamber tank in the upper sketch and a two-compartment septic tank in the lower sketch. Forbes (1992) explained where the pressure to convert to higher level wastewater treatment systems arises:

Two issues are currently being addressed by many states regarding individual home wastewater treatment (onsite wastewater disposal) and its environmental impact.

The first is how to remediate those inadequate septic tank systems which are already in place.

The second is to assure that all onsite wastewater treatment systems installed in new construction provide adequate wastewater treatment.

Many states have addressed both of these issues in a single policy.

As a result thereof, many states now require, for both existing systems and new construction, either:

• a septic tank system where the tile drain field is installed in soils capable of percolating to state defined standards and the local groundwater table is at a sufficient depth; or, the modification to

or

• replacement of the septic tank system with a system in which the effluent leaving the last sealed tankage of the system meets state defined water quality standards. - Forbes 1992

It might be easier (and cheaper) to convert the two-compartment tank shown in the lower sketch to an aerobic treatment unit or ATU system. And indeed there have been a number of patented designs

for converting a standard anaerobic septic tank system to an aerobic system where the effluent discharged has a high level of quality, sufficient to meet or exceed all known national and state standards. - Forbes 1992

While there were designs and patents for converting from an anaerobic (conventional) to aerobic (ATU) septic design for decades before, Forbes in 1992 intended to provide a conversion approach that overcame some of the costs and difficulties of older aerobic treatment conversion approaches. His criticism of his predecessors included

... they have several economic and aesthetic drawbacks.

When used to replace an existing septic tank system, or placed in series with an existing septic tank, they require excavation equipment and hoisting systems. This equipment is costly, and the cost is passed on to the owner through unit costs.

The equipment also can, and usually does, cause major damage to a yard, particularly when the ground is wet. - op.cit.

Differences Between a Conventional Anaerobic Septic Tank & Drainfield & an Aerobic Septic System

Taking a simplified view, a traditional private or onsite wastewater system consists of a septic tank and an absorption system also referred to as a soakbed, drainfield, leachfield, or soakaway bed. Sewage or blackwater and perhaps other building wastewater such as from a kitchen or laundry (graywater) flows into the septic tank.

Sludge settles to the tank bottom, floating grease and scum coagulates on the septic tank top, and clarified septic effluent flows out of the tank into a buried absorption system such as a distribution network of perforated pipes in gravel trenches.

We also call these traditional septic systems anaerobic because there is not a lot of oxygen and not a lot of aerobic bacteria active in the septic tank. Such systems perform about 45% of the necessary treatment of the sewage wastewater while the remaining 55% of treatment - bacterial action and filtering - occurs in the soils where the effluent is dispersed.

Below is a more specialized septic tank designed for use with an aerator also referred to as an aspirated mixer pump used in aerobic septic system designs.

As we explain at AEROBIC SEPTIC SYSTEMS, ATUs - topic home, aerobic septic systems or ATUs (aerobic treatment units) add oxygen to the process of treating septic of sewage wastewater by using any of several types aeration or "fine air bubble" systems to increase the level of effluent treatment in the septic tank by encouraging aerobic bacteria

. Aerobic systems produce a better-quality wastewater effluent for discharge into the absorption system for final treatment and disposal.

Spratt (1989) provided a simple flow chart showing what's needed to convert to an aerobic septic treatment design.

[Click to enlarge any image]

Aerobic septic designs use two or more separate tanks or chambers to treat the sewage and to separate solids so that the effluent that is finally to be discharged to the environment - under the soil or perhaps sprayed on top of the ground by a sprinkler system - is highly treated - perhaps to 95%.

In a four-tank aerobic septic system (or four-chamber aerobic) we'd find all of the chambers listed below, while in 2 or 3-chamber systems some of the steps below may be combined in one chamber or tank.

1. Aerobic Septic Tank Sewage receiver: a compartment to receive sewage and collect sludge;


2. Aerobic Treatment Unit Aeration Chamber: an aerobic chamber to pump air and thus oxygen through wastewater to assist in the aerobic treatment process;


3. Aerobic Septic Effluent Settling Chamber: a clarifying or settling chamber which permits remaining solids to settle out of the wastewater; disinfection may take place in this chamber;


4. Aerobic Septic Effluent Pumping Chamber: a pumping chamber to receive treated effluent for discharge to an absorption system or other destination.

Spratt's 1989 patent shows a rather complex-looking 4-chamber aerobic septic treatment unit.

Watch out: You will see from our simplified description of aerobic septic conversions hat simply plopping an aerator or air pump into a conventional single-chamber septic tank is not going to produce a properly-working aerobic septic system.

Worse, simply agitating or bubbling your sewage to death in a single chamber septic tank is going to keep the wastewater agitated. When that water, containing a high level of floating solids, flows into the absorption system or soakbed, it's going to clog and ruin the bed in no time whatsoever.

So at a minimum if we want to convert a conventional one-chamber anaerobic-treatment septic tank into an aerobic or ATU septic system we need some means of separating sludge and floating solids from effluent to be discharged from the system: usually that means adding a settlement tank or effluent pumping tank or perhaps a combination of a septic filter and a pumping chamber.

Watch out: also to get a realistic picture of the costs involved in both converting a septic system to an aerobic treatment system and the cost of maintaining an aerobic septic system.

The cost of a completely new aerobic septic system installation is about double the cost of a conventional septic tank and drainfield. But the cost of converting a working but conventional tank and drainfield septic system to an ATU might be much less, depending on how many components you're adding.

The ATU will also require more frequent maintenance and will have higher annual operating costs than a conventional residential on-site septic system.

Details about ATU operating and repair costs are in the recommended articles at the end of this page.

 

Reader Question: converting a conventional septic tank to an aerobic system

(June 3, 2015) Gene said:
I have a single 1000 gal 2 outlet fiberglass septic. To convert to an aerobic septic, I believe I would need an additional clarifier tank. Would it work to install a settling chamber inside the existing septic tank through the outlet manhole or would it be too small to be a clarifier?

Reply:

Gene,

Several manufacturers sell "add-on" aerators for conventional septic tanks.

Watch out: simply aerating a conventional septic tank is guaranteed to destroy the drainfield in short order as the added agitation will cause the system to push solids out into the drainfield. A conventional septic system needs some quiet settling time.

See EFFLUENT RETENTION TIME

Most likely it's easier, safer, and preferable to add a second clarifying chamber / tank outside the original septic tank. In my opinion 1000g is already a modest tank size and given access, safety, complexity, I'd think it's easier to excavate the outlet end of the existing tank to add a decent size settling chamber, filters, or other controls needed.

Check with the manufacturer of your tank for their suggestions.

Reader Question: drainfield is plugged, steps to improve things by going to an ATU design

(Mar 11, 2015) Robert Gibson said:
I have a 900 gallon rectangular septic tank with no baffles or partitions. The field is mostly plugged up.

Step 1.Next week I will install a T baffle on the inlet, a filter/baffle on the outlet and a man way riser above the outlet. Plus a 9" diameter fine bubble diffuser on each side of the outlet about 18" off the bottom powered by a 2.8 GPM/80L air pump.

Step 2. I was thinking of installing a settling tank in front of the main tank but I am only 10 ' from the house and the inlet/outlets would be level. An outlet tank would be level also.

I can build a block wall in the tank, say 600 gal aeration/ 300 clarification, would need to cut another hole to install/service a different style diffuser. I intend to end up with a correctly working ATU. Any suggestions?

Reply:

Robert:

I'd look into a septic tank outlet filter at the same time that you replace the missing septic tank baffles. Or if your system is clogging with laundry lint I'd add a filter on the laundry drain as well. You'll be adding a regular maintenance task but that procedure can considerably improve the life of your new septic drainfield - which is likely to be needed given what you've described.|

Watch out: none of the steps you propose will fix a failed drainfield. You'll need either a new drainfield or to convert to an aerobic treatment unit design that sprays effluent onto the ground surface - permitted in only some jurisdictions.

Reader Question: pro-active steps for an old drainfield - change from anaerobic to aerobic design?

(May 8, 2015) Gene said:

We have a cabin in the mountains that has a 1000 gal fiberglass septic tank with no baffles except T's at inlet and outlet. There are 2 drain fields separated by a valve. We normally spend only 6 months at this location. There are only two of us, but we often have visitors, some stay for weeks.

We do have a septic system that is grandfathered but by current code it is too close to a stream and our well. Any major changes would probably require a complete system replacement to meet code (not practical both financially or physically)

There are no apparent major problems with the system.

However, the system is approximately 40 years old and we are trying to be proactive and keep the system functioning properly. Should we consider changing from the anaerobic to an aerobic system to potentially extend its life? Are single tank solutions possible using either a product such as a Bio-Brush (Aero-Stream) or an Air Particle Recirculator (Septic Solutions)in lieu of a clarifier tank?

We already have installed low flush toilets, low volume showers, and sock filters on the washing machine.

We pump the septic tank bi-annually and have a filter on the outlet. We have only owned the property for the last ten years so other than some pumping records, we do not know its early history. There are no other records. We would appreciate your help.

Reply:

Gene thanks for the interesting question.

I'm sure there are other designs that we don't know about as the industry keeps evolving.

But generally no single tank septic tank that has added to it something that agitates the sewage will work without destroying the drainfield unless there is at the very least an effective and regularly maintained filter at the tank outlet. In my experience people put in the add-on features but the maintenance needed is more than anyone wants to remember so the system fails.

And no septic tank for two people that's 1000 gallons should need to be pumped as often as you are doing it. Something's wrong there.

See SEPTIC TANK PUMPING SCHEDULE for details.

(May 9, 2015) Gene said:

Thanks for the quick response. The pumper initially recommended the interval for pumping and as a septic system was new for me, I just continued it. I will review per your suggestion.
I agree that maintenance is the issue for filters.

Currently, we have advised to clean it every 6 months of usage.
As an alternative to the single tank, could the interior of the septic tank be altered by a baffle to separate the agitation zone from the clarification zone?

I may be grasping at the proverbial straw.
I do plan to follow up on the Bio-Brush and the Air Particle Recirculator and if I get anything useful, I will share.

Reply:

I'm doubtful that redesigning an existing 1000g tank to make part of it a settlement chamber is feasible.

You can by inspection see objective data that will tell you if the filter needs cleaning more or less often. I'd check monthly looking both at the extent of filter clogging and whether or not the wastewater level in the tank is too high (above the outlet opening bottom surface).

What you find on Bio Brush and the Air Particle Recirculator will be helpful to other readers.

Conversion of Septic to Aerobic Sewage Treatment, Studies, Patents, Products

• Blough, Ronald S., Jerard B. Hoage, and Larry A. Messer. "Method for vacuum aeration of septic tanks to provide low pressure microbubbles." U.S. Patent 6,245,237, issued June 12, 2001. Abstract
  
  An improved method for aeration of septic tanks and the like by drawing atmospheric air into an expansion chamber and from there into agitated sludge to provide low pressure small microbubbles which have long hold times in the sludge material.
• Blough, Ronald S. "Apparatus for aeration of septic tanks." U.S. Patent 5,194,144, issued March 16, 1993.
• Forbes, Lee W., and Stephen D. Field. "Individual home wastewater treatment plant conversion apparatus." U.S. Patent 5,162,083, issued November 10, 1992. [Illustrated at left]
  Abstract:
  
  The disclosure pertains to a method and apparatus for converting a standard anaerobic septic tank system to an aerobic system where the effluent discharged has a high level of quality, sufficient to meet or exceed all known national and state standards.
  
  The method provides a series of steps that are used to convert a pre-existing anaerobic septic tank to a highly efficient aerobic system. Additionally, there has been provided an apparatus for individual home wastewater treatment that is designed for new construction units.
  
  The conversion and new construction units are highly effective in geographical regions where the native soils have inadequate percolating capacity and also areas in which the groundwater table is very near the surface.
  
  Both of these units include an aeration and a clarifier insert with the capability of adding an optional chlorine chamber which dispenses chlorine into the effluent line in its final stages. Although only a single clarifier unit is used in each installation, provision is made for a plurality of clarifier insert configurations, any of which will meet the high quality standards indicated above.
• Gavrilescu, M. "Engineering concerns and new developments in anaerobic waste-water treatment." Clean Technologies and Environmental Policy 3, no. 4 (2002): 346-362.

• Goodman, Gerald J., "Septic to aerobic sewage treatment conversion apparatus." U.S. Patent 3,627,135, issued December 14, 1971. [Illustrated at above left]
  ABSTRACT:
  
  Apparatus for use in converting septic bacterialaction sewage systems to aerobic sewage treatment systems.
  
  The apparatus consisting of a baffle to be positioned within a septic tank structure, having inlet and outlet ports, in an inclined position dividing the tank into an aeration chamber adjacent the inlet port and a settling chamber adjacent the outlet port.
  
  At least one air diffuser mounted adjacent the lowermost portion of the baffle which is spaced from the bottom of the tank and a conduit connecting the air diffuser to an air compressor.
  
  With this arrangement and with air issuing from the air diffuser countercurrent lflows are imparted to the sewage in the aeration and settling chambers whereby continuous and complete aeration and mixing of the sewage in the tank is accomplished.
  
  In further aspect the baffle is provided with structure for returning scum from the surface of the liquid in the settling chamber to the aeration chamber, and in a further aspect the baffle is longitudinally extensible to accommodate various size tanks.
• Graham, Thomas S. "Aerobic septic tank." U.S. Patent 4,325,823, issued April 20, 1982.
• Harkin, John M., Michael D. Jawson, and F. G. Baker. CAUSES & REMEDY of FAILURE of SEPTIC TANK SEEPAGE SYSTEMS [PDF] University of Wisconsin, 1975.
  This text explains the reasons for soil clogging and septic drainfield failure. - Ed.
  
  The reason for [septic absorption ] system failure is the gradual formation underground of an imperable clogged or crusted layer in the soil blow and surrounding the seepage bed.
  
  Flow of water through this clogged or crusted zone is severely restricted or even eliminated, although the permeability of the surrounding soil remains essentially unchanged. Consequently, huge volumes of stagnant septic tank effluent accumulates in the seepage bed.
  
  See SEPTIC FIELD FAILURE CAUSES
  and
  
  See BIOMAT FORMATION & SEPTIC LIFE - Ed.
• Jewell, William J. "Anaerobic sewage treatment. Part 6." Environmental science & technology 21, no. 1 (1987): 14-21.
• Kassab, G., M. Halalsheh, A. Klapwijk, M. Fayyad, and J. B. Van Lier. "Sequential anaerobic–aerobic treatment for domestic wastewater–A review." Bioresource technology 101, no. 10 (2010): 3299-3310.
• Milne, George A., "Aerobic sewage digestion system." U.S. Patent 3,907,672, issued September 23, 1975.

• OK, AEROBIC SEPTIC TREATMENT SYSTEMS MAINTENANCE REQUIREMENTS [PDF] Oklahoma DEQ, retrieved 2023/07/01, original source: www.deq.ok.gov/wp-content/uploads/deqmainresources/YourNewHomeAerobicTreatmentSystem.pdf
  
  Excerpt:
  According to DEQ rules, the contractor that originally installed your system is required by law to maintain your system for the first two years at no additional charge to you, the homeowner.
• Spratt, Marc M., Geoffrey W. Harvey, and Thor A. Jackola. "Aeration, precipitation, flocculation, settling." U.S. Patent 4,826,601, issued May 2, 1989. Abstract:
  
  A method of treating sewage is disclosed that is particularly suitable for one or a small group of residential dwellings in environmentally sensitive areas.
  
  The raw sewage is flowed first into an aerobic first cell where it is aerated and forced into a highly aerobic condition where aerobic bacteria grow and consume phosphorus in a vigorous life cycle and then die. Substantial primary unloading of B.O.D., T.S.S., coliform, and phosphorous is accomplished in this first cell.
  
  The fluid from the first cell overflows into a second cell where additional sedimentary clarification occurs and it goes anaerobic.
  
  A third cell has an upwelling flow through a porous medium substrate where anaerobic bacteria converts nitrogen in nitrates and nitrites to nitrogen gas, and the fluid then flows into a fourth holding cell.
  
  The effluent in the holding cell can then be flowed intermittently through a sand filter that has a bed of dolemite for final removal of residual phosphorus before it flows into a drain field.
  
  Alum and methanol can be added to the raw sewage to, respectively, enhance initial flocculation and sedimentation in the first cell and to support anaerobic bacteria in the third cell.
• Stembaugh, Kasie D., Tracy A. Boyer, Garey A. Fox, BENEFITS & CONCERNS ASSOCIATED with AEROBIC TREATMENT SYSTEMS (ATS) [PDF] (2017) Oklahoma State University Extension (OSU), Ferguson College of Agriculture, retrieved 2023/07/01, original source:  extension.okstate.edu/fact-sheets/benefits-and-concerns-associated-with-aerobic-treatment-systems [dot] html
• Traverse, Charles E. "Method and apparatus for aerobic sewage treatment." U.S. Patent 4,002,561, issued January 11, 1977.
• Ward, Thomas E. "Characterizing the aerobic and anaerobic microbial activities in surface and subsurface soils." Environmental toxicology and chemistry 4, no. 6 (1985): 727-737.
• Wolverton, B. C. Aquatic plant/microbial filters for treating septic tank effluent. Lewis Publishers: Chelsea, MI, 1989.
• Zeeman, G., and G1 Lettinga. "The role of anaerobic digestion of domestic sewage in closing the water and nutrient cycle at community level." Water Science and Technology 39, no. 5 (1999): 187-194.

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2023-07-01 by InspectApedia Publisher - for people considering using an Aerobic Septic System or Aerobic Treatment System

For people considering using an Aerobic Septic System or Aerobic Treatment System (ATS) or (ATU), we recommend this article as well:

Stembaugh, Kasie D., Tracy A. Boyer, Garey A. Fox, BENEFITS & CONCERNS ASSOCIATED with AEROBIC TREATMENT SYSTEMS (ATS) [PDF] Oklahoma State University Extension (OSU), Ferguson College of Agriculture, retrieved 2023/07/01, original source: extension.okstate.edu/fact-sheets/benefits-and-concerns-associated-with-aerobic-treatment-systems [dot] html

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On 2023-07-01 by InspectApedia Publisher - most common Aerobic Septic System Problems

@Kim,

Continuing, for other readers, common OPINION among septic pumping contractors who serve aerobic septic systems is that the following are the most common Aerobic Septic System Problems:

1. ATU alarm sounds because power to the system pump has failed. Check that the breaker or fuse powering the system is "on".

2. Aerobic Septic Chlorinator or chlorine injector system is clogged. In many ATUs chlorine is injected into the effluent as that liquid is being dispensed to a spray or underground dispersal/disposal system. Check for clogging in the chlorine injection system.

3. Aerobic Septic System effluent pump failure: the pump may fail to turn on because of a damaged or stuck float switch or, less common, a loose or failed electrical connection or a failed pump itself. High effluent levels in the tank combined with the pump not turning on mean you need help from your ATU maintenance company to diagnose and fix the ATU pump or its control.

4. Aerobic Septic System air pump trouble: inadequate air flow, low air pressure, clogged air pump tube or failing air pump itself can cause the aerator to fail. Check first for a kink or clogging in the air tubing or aerator outlet. If the pump isn't running or is making grinding or other noises it may need replacement.

5. Aerobic septic system sprinkler failures: for systems that use sprinkler heads, some of our readers report clogs or broken individual sprinkler heads or clogs or broken effluent piping feeding the sprinkler system. Has a lawn mower run over or damaged a sprinkler head?

6. Aerobic septic system timer or photocell control failures: less common, a timer or photocell that controls the operation of an ATU effluent dispersal pump can lead to ATU alarm and may need repair or replacement.


What about regular Aerobic Septic System maintenance?

ATUs do require regular maintenance (so do other septic systems):

See details at AEROBIC ATU SEPTIC MAINTENANCE PROCEDURES
inspectapedia.com/septic/Aerobic_Septic_Maintenance.php

We note that depending on where you live, your state or provincial DEQ or DEP may require that for new aerobic septic systems the installing contractor must provide regular maintenance for two years at no extra cost - that's part of the system's installation cost.

EG See this

252:641-10-3. Responsibility for Maintenance

A. Mandatory two-year maintenance period. The installer of any aerobic treatment system, including those providing nitrogen reduction, shall maintain the aerobic treatment system for a period of two years, following the date the
system was installed, at no additional cost to the owner.

During the two-year mandatory maintenance period, the installer shall be responsible for the following:

1. Repairing, adjusting or replacing any broken or malfunctioning parts;

2. When spray dispersal is used, testing and recording the free chlorine
residual of the effluent in the pump tank at least once every six months;

3. Measuring and recording the depth of the sludge in the trash tank at least
once every six months;

4. Measuring and recording the volume of the sludge in forced-air aerobic treatment units at least once every six months;

5. When pump tanks are used, conducting a clarity test and recording the results as passing or failing once every six months.

A passing clarity test is one where an eight-inch disk with alternating black and white quadrants is visible when placed on the bottom of the pump tank when the tank is at least one-third full;

6. Notifying the owner of the system in writing of:

a. The type and date of any repairs, adjustments or replacements performed on the system;

b. The results of the free chlorine residual test if required and, when applicable, the need to add chlorine and how to do it;

c. The depth of the accumulation of sludge in the trash tank and the need to have it pumped so that the depth of the sludge is never more than 40 percent of the overall depth;

- original source: www.deq.ok.gov/wp-content/uploads/deqmainresources/YourNewHomeAerobicTreatmentSystem.pdf

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On 2023-07-01 by InspectApedia Publisher - Will my aerobic septic system be ruined if I don’t use it for an extended period of time?

@Kim,

From our research and experience, if your aerobic septic system or "ATU" has been properly maintained and is in good working order, you can safely leave it for a month at a time without concern that sitting idle will damage the system.

However, and arguing with myself, if your home is located in a freezing climate, any elevated or above-ground effluent disposal system such as an aerobic effluent dispersal by spray above ground or even a septic mound system can freeze-up if left idle for a month or more in freezing weather.

We discuss that concern at SEPTIC FREEZE-UP SOLUTIONS https://inspectapedia.com/septic/Septic-Freeze-Up-Solutions.php

While it's not an exact fit for aerobic systems, this statement from the Butte County California disaster response and recovery department buttecountyrecovers.org is helpful:

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Will my septic system be ruined if I don’t use it for an extended period of time?

A standard septic system that was working properly and then not used for a period of time, such as 4 – 5 years, typically does not lose effectiveness or the ability to function properly once it is put back into use. Some of the older septic systems may even benefit from non-use by allowing some of the biomat, which is a biological clogging layer in the leachfield, to naturally break down and the soils rejuvenate.

Septic systems with gravelless chambers used for leachfields are more prone to becoming less effective over time when they are not in use. This is because gravelless chambers are like long open tunnels underground that without wastewater flowing through them burrowing animals, like moles, can enter into them and begin to fill them with soil.

Septic tanks, whether made from concrete or plastic, typically do not degrade or lose effectiveness when not in use. It is best to keep septic tanks full with water when they are not in use. This is because most empty septic tanks are not designed to withstand the exterior forces that are placed upon them from surrounding soil and groundwater when they are empty.

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What about idle aerobic septic systems?

Your aerobic septic system will usually use an air pump to improve the level of treatment in the septic tank. Leaving that pump running when no new wastewater enters the tank is harmless. But readers often report problems with their ATU aerator such as pump failures. So on return home to your Aerobic Septic System, check for warning lights that indicate that your pump is not working or that there's an abnormal level of water in the treatment tank. Those problems can arise and need attention but are NOT caused by simply leaving the aerobic septic system out of use for a time.

Help us out by going back to whoever was who told you that there are ATU system issues if you are away from home for weeks at a time, and ask that person for specific details or for citations of specific articles or expert sources that we can then review and discuss here.

Thanks for a helpful question. DF.

On 2023-07-01 by Kim

We're looking at installing an ATU for our new house. I've been told that there are issues with the system if you travel frequently for several weeks at a time. We are gone about 35% of the time. If this is an issue is there anything we can do to prevent or minimize the problem.

On 2023-07-01 by InspectApedia Publisher - best brand of bio enzyme or bacteria that you can recommend to be used in biofil

@Fayose Olasunkanmi,

Apologies but I'm not sure what you're asking. Are you asking about using a submerged biofilm that claims to improve septic system treatment levels? Or are you asking about septic additives and treatments in a more general way? Or are you asking about the biofilm that forms naturally around septic effluent disposal drainfield trenches?

Meanwhile, please take a look at CHEMICALS & TREATMENTS for SEPTICS

and let me know if that answers your question.

On 2023-07-01 by Fayose Olasunkanmi

@danjoefriedman, please what is the best brand of bio enzyme or bacteria that you can recommend to be used in biofil?
WhatsApp +2348130585651

On 2022-08-23 by InspectApedia-911 (mod)

@Stephen N,

Thank you so much for your very nice note. It means a lot that you took the time and trouble to comment as you did, and of course I'm very happy that our information proved helpful to you.
Indeed we have worked hard for over twenty years to make information at InspectAPedia.com accurate, in-depth, and without bias, so I am of course very grateful when a reader reports that our website has been useful.

To that end, we appreciate hearing any comments, critique, suggestions, or further questions that you may have about any of our diagnosis/repair articles.

On 2022-08-23 by Stephen N

@InspectApedia-911, Thanks so much! This has been super helpful and will definitely save me a lot of money!

On 2022-08-22 by InspectApedia-911 (mod)

@Stephen N,

Also have on hand

STANDARDS FOR INDIVIDUAL SUBSURFACE SEWAGE DISPOSAL SYSTEMS - New Jersey [PDF] Statutory authority: N.J.S.A. 13:1D-1 et seq.; 26:3A2-21 et seq.; 58:10A-1 et seq., including 58:10A-16 ; 58:11-23 et seq. Date last amended: July 6, 2021
- original source: www.state.nj.us/dep/dwq/pdf/njac79a.pdf

Copy at

NEW JERSEY SEPTIC SYSTEM LAW [PDF]

inspectapedia.com/septic/New-Jersey-Septic-System-Law-2021.pdf

You'll see seepage pits discussed beginning on page 109

IMPORTANT EXCERPT
7:9A-11.1 Site/soil requirements
(a) Seepage pits shall not be approved except as specified in N.J.A.C. 7:9A-7.6. When a seepage pit is approved,
the following site/soil requirements shall be met:
1. The bottom of any seepage pit shall be a minimum of eight feet above any hydraulically restrictive horizon
or substratum not fully penetrated or any massive rock substratum.
2. The bottom of any seepage pit shall be a minimum of four feet above any fractured rock substratum.
3. The bottom of any seepage pit shall be a minimum of four feet above the level of the seasonally high water
table.

see the code for more details

On 2022-08-22 by InspectApedia-911 (mod) - seepage pit failure - the pit is full and no longer adequately accepts & disposes of septic effluent

@Stephen N,

Thank you for a helpful seepage pit failure question/discussion.

What you describe is a seepage pit failure - the pit is full and no longer adequately accepts & disposes of septic effluent leaving your septic tank.

Although you are posting on a page about Aerobic Septic Systems, that’s not what you have installed.

You have an outdated septic system that combines a septic tank and seepage pit - a design that is illegal in many jurisdictions and might not be permitted in New Jersey where your property is located.

Please be sure to read

DRYWELL / SEEPAGE PIT COLLAPSE or FAILURE

https://inspectapedia.com/septic/Drywell_Failure.php

Seepage pits dispose of effluent but because they’re deeper than a conventional septic drainfield they don’t adequately treat the effluent; as a result pathogens are discharged into the environment, nearby groundwater, wells, etc.

Seepage pit septic designs are usually found on small sites where there was not room for a conventional septic drainfield.

So before spending a dime on installing a new seepage pit, check with your local building or health department to find out what they will accept. Otherwise you could be spending money uselessly or having to do the job over again.

Also take a look at New Jersey’s restrictions on cesspools (no septic tank, just a pit) -

“Amendments to N.J.A.C. 7:9A Regarding Cesspools and Inspections for Real Property Transfers - An Update” [PDF] - original source: https://www.nj.gov/dep/dwq/pdf/tnef2.pdf

copy here at

https://inspectapedia.com/septic/New-Jersey-Cesspool-Law-Update.pdf

And to understand the difference between a septic tank + seepage pit design and a cesspool design

see also CESSPOOLS

at https://inspectapedia.com/septic/Cesspool_Guide.php

You’ll want to be conversant with the difference between these two designs to navigate discussions with your department of health or building department.

On 2022-08-22 by Stephen N

@InspectApedia-911, Finally got a real septic inspection:

The system contains three main components: the treatment tank that traps the solids, the conveyance system which moves the liquid from the treatment tank to the absorption area and the absorption area where the liquid percolates into the ground.

The treatment tank was opened and inspected. The baffle that directs the solids to the base of the tank (inlet baffle) was found to be intact and operational. The baffle that prohibits the floating solids from leaving the tank (outlet baffle) was found to be intact and operational as well. There was no visible cracking or damage noted to the tank. The tank was not pumped for this inspection and the condition of the tank below the liquid level could not be seen. This is considered satisfactory.

The conveyance system in this case is simply a pipe that runs from the treatment tank to the absorption area, which is a seepage pit. A fiber-optic camera was run through the line and it was found to be intact and operational. This is considered satisfactory.

The absorption area for this system is a seepage pit, which is a perforated concrete tank surrounded by stone that allows the liquid to leach into the ground. The main lid of the seepage pit was opened, and Ever-Green found that the liquid level in the pit was at the inlet invert prior to testing. Clean water was introduced to the system and we observed the liquid level in the pit immediately elevate to approximately half-way up the inlet invert of the pit. This is indicative of a saturated absorption area and is considered unsatisfactory. We also observed floating solids inside of the seepage pit.

We recommend that a septic contractor/engineer is contacted to replace the existing absorption area.

On 2022-06-07 by InspectApedia-911 (mod) - conventional septic system uses a septic tank and drainfield. There is no "seepage pit"

@Stephen N,

I'm baffled.

A conventional septic system uses a septic tank and drainfield. There is no "seepage pit" - so I don't know what your inspector was inspecting.

I don't even know if your septic system is an aerobic septic (described on the page above) or a conventional septic tank and drainfield, or something else.

Start at
SEPTIC SYSTEM INSPECT DIAGNOSE REPAIR - home

Conventional septic tanks are water-tight - they are not "Seepage pits" and are described on that page also.

And if there were actually a "seepage pit" into which sewage is flowing on your property, it'd be described and discussed

at CESSPOOLS

Frankly, not to put too fine a point on it, If your septic inspector doesn't know what these components are, she or he ought to be doing something else for a living.

On 2022-06-07 by Stephen N

@Friedmandaniel911, Thanks! It's not backing up into the home toilets or sinks and it's not seeping up through the ground yet, but I had a septic inspection a year ago when I was planning to sell my house that basically just said: we see a few solids in the seepage pit, the seepage pit level is too high, it's time to replace the whole system.

I think if I get a new septic inspection from a more reputable inspector that actually diagnoses what's going on, does scopes, etc. I may find enough info.

On 2022-05-19 by Friedmandaniel911 (mod)

@Stephen N,

I'll be glad to help however we can.

Let's start with a bit more information about your system.

Am I correct that you have a conventional septic system - tank and drainfield - and the drainfield has stopped working: either seeping effluent to the surface or backing up into the building?

If so, unfortunately, adding a septic aerator will not fix the problem. What's needed is more trouble and expense: quite possibly a drainfield replacement.

But before pouring money into the ground, let's get more diagnostics, including checks in the septic tank, at the D-box, and perhaps with a sewer line camera so that we can rule out something easier to fix: a broken or clogged line.

On 2022-05-19 by Stephen N

I have a septic system that has a lid (manhole cover, not one of those green risers that most systems have) for the septic tank and another lid for the seepage pit. Will adding an aerator directly to the septic tank or the seepage pit make sense?

I have 3 little kids, so we go through a ton of laundry. The town flat-out refused to let me do a separate field for the gray water from the washer (apparently that's a law in NJ), so I really need to figure out how to get this drain field to actually drain.

On 2021-04-16 by danjoefriedman (mod) - Will a septic aerator help to unclog my seepage pit?

@art bontemp0,

No, an ad on septic aerator will not unclog AC Peach Pit that's already clogged. The seepage pit is clogged is because the soil around the pit has developed such a thick film of biomed that is no longer passes fluid into the surrounding soil. The solution is to add another seepage pit or, more-costly, dig up, remove, and replace the existing one.

Keep in mind that is seepage pit or cesspool will never treat sewage effluent it will only dispose of it. That's because it's so deep in the soil that there is not sufficient oxygen for all of the aerobic bacteria to process the sewage pathogen's. It's also the case that in some communities see seepage pits / cesspools might be no longer allowed.

Please read details at CESSPOOL FAILURE CRITERIA

And don't hesitate to post follow up details or questions or comments.

On 2021-04-16 by art bontemp0

Will a septic aerator ( septic genie) help to unclog my seepage pit,the house is a very small 2 bedroom house with a functioning 1000 gallon septic that leads to a 6ftx 8ft seepage pit that is clogged Thank you

On 2021-02-10 by (mod) - is it an advantage to -use a 1250 gal two compartment septic tank and a pumping chamber that I aerate?

Sure Jack but in my OPINION it would make more sense to use a design from a licensed septic engineer or from a company providing packaged systems than to make up our own system without their help.

On 2021-02-10 by jack ehlers

building a new house in the country. Is it an advantage to -use a 1250 gal two compartment septic tank,then run into a (for example) a 200gal tank and aerate the 200 gal tank and then to D Box

On 2021-01-01 - by (mod) -

Glad to assist. Stay safe. Happy New Year.

On 2021-01-01 by Dan

Argh! I hoped that might have worked. I will start researching installing a new cesspool downstream. Thanks for your input.

On 2020-12-31 by (mod) - this Cesspool is at end of life

Dan

If we take note that the purpose of the Cesspool was intended to dispose of the liquid effluent and the Cesspool no longer does that it's because the soil around the Cesspool has become clogged with grease and Biomat. Although there are some processes that try to extend the life of a cesspool they may not be safe and in any case they don't have a long life.

Instead what people usually do in your circumstance is to daisy chain a new Cesspool Downstream from the old field one and put the new one to work as an extension off of the one that has failed.

If you try adding anaerobic pump to the Cesspool that will not improve the disposal of liquid effluent.

On 2020-12-31 by Dan

I have a 900 gallon septic tank that outlets to a lower cesspool covered 900 gallon pit that was backing up. Pumped both and found no solids in the pit so I assume the baffles are ok in the tank. Pit level still slow to drop. I would like to add air with a diffuser to the pit creating an aerobic pit to eat away any mat that has developed over the years. Does this seem reasonable? Dan

On 2020-05-26 - by (mod) -

You could, Joe, but I would check with a local septic engineer first. It would be well worth the consulting fee, since if your tanks are too small (as I suspect) or improperly-aerated you end up pushing solids into the drainfield and ending its life.

Also I'd like a filter on the outlet tee of the final settlement tank.

On 2020-05-26 by Joe

Problem is that first tank in the 3 tank system gets clogged often and plugs under inlet pipe to second tank.

How can I convert my traditional septic tha has 3 separate 250 gallon tanks hookedup in series before leading out to drain field? Coud I get by with simply aerating the middle(2nd) tank?

On 2018-10-29 by (mod) -

"VIable"
may be subjective,

I cant argue with 15years of usage

But at what volume?

as with too many small tanks, at normal usage monthly clean out may be needed

On 2018-10-29 by (mod) -

mike said:
love to know from experts if this link is a viable system design.

series of 7) 250 gallon tanks 1st separator tank followed by 2 anaerobic tanks followed by 3 aerobic tanks with air diffusers and growth media and a final chlorine tablet tank. This guy in Australia has been operating it for 15 years.

On 2017-05-13 by (mod) - "add-on" aerobic system products sold that add air to the septic tank

Roger,

You'll need to know more specifically what's wrong with your septic soakbed or drainfield and thus to know just what repairs are needed before deciding to face the trouble and cost of a complete conversion of the system.

There are "add-on" aerobic system products sold that add air to the septic tank - thus agitating it and ruining the drainfield if just that process is added without additional features such as

- additional septic tanks or settlement tanks or at the very least septic filters at the tank outlet - something that works well but that fails often due to lack of maintenance as nobody wants to change the filters

- additional pumping system and effluent dispersal system for aboveground effluent disposal if that's part of your design

- a review of your design and approval by your local health or building department

Watch out: adding any aerator, pump, or other system or chemical or product (such as yeast) to a septic tank that has the effect of keeping sewage agitated and thus solids in suspension can quickly destroy the septic drainfield if those solids escape the septic tank; your tank must be designed to retain solids and allow settling of them before effluent is discharged to the drainfield

or

you'll need a septic filter at the tank outlet.

On 2017-05-13 by Roger

My field was not install properly and my tank is 10 years old what do I need to do to change to aerobic and how.

On 2017-04-26 by (mod) -

In concept,. I would check with a septic engineer, get some specifications, and then take that to your local approving Authority, probably your health department it would make sense to get approvals before spending money on such a project.

On 2017-04-26 by Abiel

I have two 500 gallons tanks that connnected to a drain field. I want to know if I can convert it to an aerobic system by adding a filter in the sludge tank and aerator to the second 500 tank after the tank with the filter. Then I add another smaller tank where I would pump to sprinklers.

On 2017-02-09 by (mod) - Solid pipe just runs from the outlet now about 40 yards into a wooded area where it discharges into coarse rock.

Blee

Watch out: What you are describing is not a valid functional septic system and typically would violate Health codes in most communities. However it's possible that you were simply using terminology that you don't intend. For example a septic tank is a watertight container that holds sewage and effluent and must have a way to send it's a fluid to a drain field.

In contrast a seepage pit or cesspool would not be connected to a separate drain field. My suggestion since I don't understand what you have installed is it you ask for an inspection and advice from a private septic designer or engineer.

On 2017-02-09 by blee_63628@yahoo.com

I have a concrete septic tank, but no drain field. I live in an unincorporated area and built 40 years ago.

Thinking about selling our property, and wanted to avoid problems.

Would it help if I just added a smaller tank after the original tank to get further settling. I have had the tank pumped 3 times and have never had a problem.

Solid pipe just runs from the outlet now about 40 yards into a wooded area where it discharges into coarse rock. What else can I do to enable selling without having problems? Thanks

On 2016-03-01 by (mod) -

You can convert non-aerobic to aerobic septic systems but I cannot recommend simply adding an aerator to a simple septic tank. Doing just that will ruin the drainfield in short order by sending floating solids into the fields. You'd need a multi-compartment tank and/or filters at the tank outlet, combined with a regular maintenance program. NSF and others have long demonstrated that the No. 1 reason for failure of aerobic septics is lack of maintenance.

High effluent in your pumping tank suggests either a failed, flooded drainfield or a clogged pipe or D-box.

But converting to an aerobic system will not fix a flooded drainfield.

If the fields are saturated and clogged you need new fields.

If the fields are exposed to seasonally high water tables, you need new fields, perhaps built as a mound or raised-bed septic that gets the bottom of your fields well above the high water level. Otherwise your system cannot treat the effluent successfully.

Sprinkling effluent above grade works in some locations that are basically dry. That won't work if sprinkling onto a wet area. And your local septic authorities may not approve it anyway.

Start by finding out what types of system your local authorities will approve. Continue by testing and documenting the soil conditions at your site, thus suggesting what sort of septic design can work there. You probably need a septic engineer.

On 2016-03-01 by Carl

I have a 16 year old anerobic system. The system consists of a sludge tank and a pump tank. My lateral lines are, for lack of a better description, an underground drip system that requires a pumping of the effluent ( minus solids) to the field. We are experiencing high water events in the pump tank every couple of months. The field is heavily treed and regularly has wet spots.

The question is can the pump tank be converted to a aerobic system and leave the current sludge tank as the sludge collection point? A sprinkler system would be used to disperse the final water.

I appreciate your thoughts.

...

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• AEROBIC ATU SEPTIC FAILURE RATES, COSTS
• AEROBIC SEPTIC CONTINUOUS FLOW, Suspended Growth
• AEROBIC SEPTIC SYSTEM MAINTENANCE COSTS

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