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PHOTO of new construction placing septic system components in a wet area.Causes of Septic System Drainfield / Soak Bed Failure

What causes a septic system failure?

This septic system diagnosis article explains the causes of septic system failure in the drain field, leach field, seepage bed, or similar component.

We list the causes of each type of septic component failure, and list the septic component failure criteria or in other words what conditions are defined as "failure"?

We also discuss what can be planted over and near a septic drainfield and what should be avoided.

How can you distinguish between a blocked pipe, a septic tank that needs pumping, and a clogged drainfield that needs replacement? This is an important question as it distinguishes between relatively low cost maintenance or repair task and a costly septic leach field replacement.

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Septic Absorption Field Failure Causes: what ruins septic drainfields, leaching beds, soakbeds, or soakpits?

PHOTO of a northern Minnesota field where we have ample room to keep septic components well away from the trees - but notice those tire tracks?Here is a list of the causes of sewage wastewater disposal field failures. These factors explain why soakaway beds, seepage beds, leach fields, disposal fields, drainfields, or other synonymous effluent treatment & disposal systems fail early or at the end of a normal life.

Nevertheless a number of additional factors can hasten the demise of a septic soakbed or leachfield.

Research on Avoiding Soakaway Bed Failures

 




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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2020-07-19 - by (mod) -

Thanks for a helpful question, Brad.

If there is too much fill over a septic field you deprive the soil bacteria of oxygen. The result is that half of the two types of bacteria (aerobic and anaerobic are the two) can't do their job of breaking down sewage pathogens.

The result of that is that even if you are successfully disposing of effluent you're not successfully treating it. Ultimately such a system contaminates groundwater and nearby wells or water sources. And you may also see a reduced drainfield life.

In fact, the very process of adding backfill over an existing septic drainfield may itself destroy the drainfield by the weight of vehicles carrying soil and dumping and grading it out: compressing the soil and/or breaking pipes.

On 2020-07-19 by Brad

What issues arise from putting too much fill over a septic field? I am constructing a new house and the septic system was installed without any thought to the eventual elevation changes we'd be brining to the site. As a result the "completed" drainage field is many feet lower than the expected grade. If additional fill was brought in how would the system possibly be compromised?

On 2020-07-11 - by (mod) -

Cassie

That describes a failed drainfield

Dirt can get into the drain lines as a result of:

- broken piping anywhere along the line

- tree root invasion

- improper original construction with insufficient gravel around the pipe OR in soil with many fine particles, omission of an appropriate geotextile above the drainline trench during backfill

And standing water in the remaining line tells us that the drainfield area is saturated, not accepting effluent, and thus is not functional;.

Sorry to say it's almost certainly time for a new field. (Just clearing the pipes will give but short relief and is IMO a waste of money on a failed leach field)

On 2020-07-11 by cassie

2 of the three lines are full of dirt, one has standing water. What would be the cause of a dirt filled line? Can moles be a culprit?

On 2020-05-24 - by (mod) -

Sarah

That can work in some (not all) situation, and is certainly not "illegal": directing surface runoff away from a drainfield and installing subsurface drainage trenches around the field to intercept and remove subsurface groundwater can help dry out the drainfield area.

But I'm not optimistic. If the area is one of wet soils we can be trying to remove more water than is feasible.

A local septic engineer who knows various designs, has done a soil perc test, and knows what designs the local septic authority will accept is someone who could be helpful in the case you describe.

As Mark Cramer (Tampa FL home inspector) says: ... it depends.

In this case it depends on local site conditions: terrain shape, drainage, water levels, etc.

On 2020-05-23 by Sarah

he had the installer come and look at everything, and (this is according to my father-in-law passing on the info to me), the field has some sort of "barrier" around it to keep groundwater out. There is some kind of berm at the end of the field that was really high or something (not sure), but either way, the grey water from the field had nowhere to drain.

So the installer is going to charge him $1000 to dig a drainage trench to go even farther somewhere and drain into the trench (which will be filled with stone or sand or whatever it is that's supposed to go in a trench).

I asked him to get a copy of the plans, showing his current setup, and the proposed work.

This does not sit right with me. Is that even legal to have a "barrier" around a leach field?

On 2020-05-22 - by (mod) -

The bottom of a drainfield trench needs to be 2 ft. above the seasonal high water table for a septic system to work, so i agree with you.
And no, the failure may not be obvious right away.

On 2020-05-22 by Sarah

they also live in a very boggy area. Is it possible that the wrong septic system was installed (ie, they should have had a mound system)? Or would that mean that would have had issues right away?

On 2020-05-22 - by (mod) -

Yes that failure cause is likely. As you infer, stirring the septage increases passage of clogging solids into the drainfield.

On 2020-05-22 by Sarah

My father-in-law has a saturated leach field. It's less than 5 years old. He took the (bad) advice of a septic pumper and was adding Septobac (bacteria/enzymes) to his septic system. He also stirred up the first tank every 4 months. He does have an effluent filter. He also did have solids and sludge make it into the second tank (where there should be only water). Is it possible that his actions caused his leach field to clog? Would Septobac and stirring the tank cause a leach field failure within 5 years? It's just him and my mother-in-law who live in the house.

On 2019-12-13 - by (mod) -

Unfortunately constant septic tank pumping never fix a failed leachfield (and cost you plenty).

In wet swampy terrain we often find that when the septic tank is pumped water flows backwards from the saturated drainfield into the septic tank, re-filling it in a day or so - it's basically a waste of money to pump in this case.

I don't have a low-cost solution. What's needed when a septic field was improperly built in the first place, locating it in ground that is seasonally (or always) flooded or wet, is to abandon that drainfield and construct a raised-bed septic or mound system.

Until that's done, what's happening is that each time you flush a toilet sewage effluent is in essence being discharged to the ground surface.

On 2019-12-13 by Linda Shull

We bought a house built on a piece of swampy land. We have had trouble with our septic system every since we moved in. Especially in the winter. Our house was built in 79.

We had the tank pumped and have been adding rides monthly. Is there anything else we can do. We are both retired and living on a very limited income so can't afford any thing really costly. Thank you .

On 2019-07-28 - by (mod) -

On 2019-06-26 by Gkw44 - Nostoc commune is an algae - not quite a fungus

Moderator comment: this septic field failure report discusses the presence of Nostoc commune, a cyanobacteria algae like growth over a drainfield that was diagnostic of a drainfield failure. Nostoc looks like bear poop. It's not.

Details are at SOAKBED SOIL CONDITIONS https://inspectapedia.com/septic/Leachfield_Soakbed_Soil_Conditions.php


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