How to spot drainfield clogging failures:

This septic system inspecting testing and maintenance article describes septic drainfield (soakaway bed, leach field, drainage trench) clogging failures among the types 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?

Wastewater Disposal Field Clogging Failures / Septic Effluent Disposal and Septic Drainfield Failures

[Click to enlarge any image]

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

1. First see CLOGGED DRAIN DIAGNOSIS & REPAIR - is it a problem in the building? Here we give a 12 step procedure to diagnose & fix a blocked or slow plumbing drain.
   
2. Next see SEPTIC DISPOSAL FIELD CLOGGING INSPECTION - you are on this page
3. Also see SEPTIC DRAINFIELD RESTORERS? where we describe the use of chemicals, treatments, septic tank additives, to try to restore failed or failing sluggish septic drainfields or leaching beds or soakaway beds.
4. Watch out: if your drains are blocked or there is evidence of a septic field failure, pumping the septic tank will never "fix" that problem, though it may give a few days of relief. For advice on when to pump the septic tank
   
   see SEPTIC TANK PUMPING SCHEDULE

There is an important distinction between septic effluent disposal and septic effluent treatment.

Traditionally people figured that if they could flush toilets and use sinks and showers without seeing septic effluent again outside on the ground surface, the septic system was "working fine". Really this describes successful effluent disposal - getting rid of the liquid waste.

And when effluent disposal failures occur, people are forced to repair or replace the septic system or drainfield.

Successful septic effluent treatment (as opposed to disposal) means that the effluent being released to the environment (as ground water for example) is sufficiently sanitary as to avoid contaminating nearby wells, rivers, streams, lakes, etc. with pathogens or chemicals from the wastewater.

We explain this point further at DISPOSAL vs TREATMENT.

Two Visible Signs of Drainfield Failures or Blockage

In simplest terms, there are two visible septic effluent or onsite wastewater disposal failures:

• Toilets or other fixtures back up into the house - but first
  
  see DIAGNOSE CLOGGED DRAINS then return here using your browser's 'BACK' button.
• Effluent or sewage appears at the surface of the yard, or the neighbor's yard! Wet spots can be caused by more than a septic failure.
  
  You might need to use a SEPTIC DYE TEST PROCEDURE if you can't diagnose this condition by simply running or not running water into building drains.
• Septic odors may also indicate a system failure or an imminent failure. But such odors may also be produced by defects in the plumbing vent system or other site conditions. Beware, sewer gas contains methane and is explosive if it reaches a dangerous concentration inside a building.

 

Common Causes of Sewage Backups & Drainfield Failures

Typical causes or symptoms of apparent septic drainfield failure range from things that are easy and cheap to repair, to a need for complete system replacement:

• Clogged building drain 
  or septic system effluent distribution pipes
  
  See CLOGGED DRAIN DIAGNOSIS & REPAIR
• Broken drain pipes or septic effluent distribution piping 
  
  anywhere in the system, starting between the building and the septic tank or even inside the building.
  
  See SEPTIC TANK, HOW TO FIND and related articles can help trace piping.
• Damaged septic tank -
  
  if the tank baffles are damaged it's easy to replace them, and not costly, but you may have already sent sewage solids out into the drainfield, reducing its future life.
  
  See SEPTIC TANK INSPECTION PROCEDURE
  and
  
  see SEPTIC TANK BAFFLES
  and
  
  see SEPTIC TANK TEES
• Tipped septic effluent distribution box -
  
  find and inspect and fix the D-box and you may be back in business. Often a tipped D-box is sending all of the septic wastewater down just a portion of the drainfield, overloading it and causing an apparent failure.
  
  See SEPTIC D-BOX INSTALL, LOCATE, REPAIR.
• Clogged/broken leachfield or drainfield soil absorption piping -
  
  find, diagnose, and repair the pipe and you're back in business
  
  See CLOGGED DRAIN DIAGNOSIS & REPAIR
• Clogged drainfield or soakaway field absorption soils
  
   around the drainfield piping or trenches, (often by salts, grease & solids, or by an over-aged too-thick biomat) - people try magic bullets, additives, restorers, but despite testimonials and advertising by companies selling these restorers, we have had few reports of lasting, effective success. You may need a new septic drainfield, or you may be able to switch to an alternating drainfield or set of trenches to rest and recover the sluggish section.
  
  See SEPTIC DRAINFIELD LIFE.
  
  See SEPTIC DRAINFIELD RESTORERS.
  
  Also see septic drainfield clogging at SEPTIC DISPOSAL FIELD CLOGGING INSPECTION.
  
  Drainfield soils can become clogged or drainfield pipes can be broken and crushed by driving equipment over the drainfield
  
  See DRIVING OVER SEPTIC SYSTEMS
• Water-saturated drainfield soil absorption area - you may need to replace the entire drainfield, switch to an alternating bed or set or septic fields, or it may be possible to direct surface and subsurface water from other sources away from the drainfield area.
  
  See SEPTIC DRAINFIELD LIFE.
  
  See SEPTIC DRAINFIELD RESTORERS.
  
  Also see SEPTIC DISPOSAL FIELD CLOGGING INSPECTION.

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Question: How to distinguish between a 1. blocked pipe, 2. a septic tank that needs pumping & 3. a clogged drainfield that needs replacement?

How can you distinguish between a blocked pipe, a septic tank that needs pumping, and a clogged drainfield that needs replacement?

You need to clarify this discussion. - Amy 2021/06/05

Moderator reply:

Right-on, that's the 64 thousand dollar question.

Watch out: if there has already been a sewage backup in a building there are immediate health hazards as well as a need for prompt cleanup to avoid a costly mold catastrophe in a few days.

See BACKUP, SEPTIC-SEWAGE WHAT TO DO

1. Is it Blocked Drain Line or "pipe" ?

1.a. we have a local blockage at one fixture trap, or one drain, but not the building main drain nor septic system:

if some drains run fine and free but others keep backing up then there is a local blockage

(the more water we run down a drain before we see the backup the further away from that drain is the blockage)

Watch out: when testing drains remember to check the lowest drains in the building - toilets, showers, floor drains - to be sure we're not running water upstairs that's pushing sewage out of a lower drain downstairs.

Usual repair:

the plumber tries to run a snake (not a real one) down the drains to see if she finds and clears a blockage - if that works we try living with that for a few days or longer to see what happens.

If blockages are recurrent we have the drain inspected with a sewer line camera to look for damage or a hard-to-clear blockage (like rust crud in old galvanized iron drains).

1.b the building main drain is blocked between septic tank (or sewer line inlet for public sewer connection) and the house:

All building drains are slow or backup. - at that point, without inspecting further we don't know for sure where the trouble lies.

Inspecting at the septic tank we see that the wastewater level in the tank is normal (not above the inlet nor outlet pipe bottom)

Inspecting at the septic tank we don't see flood lines indicating that the tank has been sometimes above its proper maximum level:

Inspecting outdoors we don't see sewage effluent coming up in the drainfield area

Watch out: don't try opening or inspecting your septic tank if you are not trained in septic tank safety: leaning over a tank you can be asphyxiated; falling in is quickly fatal.

See SEPTIC TANK SAFETY

Usual repair:

the plumber tries to run a snake (not a real one) down the building drain and out to the septic tank to see if she finds and clears a blockage - if that works we try living with that for a few days or longer to see what happens.

If blockages are recurrent we have the drain inspected with a sewer line camera to look for damage, sags, roots, etc.

But

it might save time to also have the conditions in the tank inspected - see below.

2. Do we Just Need to Pump the Septic Tank?

No. if we already have a sewage backup or failed drainfield then pumping the tank won't fix anything - it's too late.

As a regular maintenance chore we have the septic tank pumped to stave off that failure.

The septic tank is pumped either on a regular schedule or by actually measuring the thickness of settled sludge and floating scum - if those accumulations are excessive there is insufficient net free area in the tank, insufficient solids settlement time, and the result is small floating sewage particles are pushed out into the drainfield thus shortening its life.

These articles discuss this:

SEPTIC TANK LEVELS of SEWAGE - and what they mean

MEASURE SEPTIC TANK SCUM & SLUDGE - how a septic gal actually makes the measurement - an alternative to just pumping on a regular schedule is to get actual data of conditions in the tank

SEPTIC TANK PUMPING SCHEDULE - based on a simple schedule, or

also see WHEN to CLEAN THE SEPTIC TANK - don't waste money by pumping too soon nor by pumping too late

At the septic tank: if sewage levels are or have been abnormally high (above the inlet or outlet baffle at times, or steady above the bottom of the outlet pipe) then
- the effluent line between septic tank and septic distribution box (D-Box) and drainfield is clogged or damaged
or
- the septic drainfield is in failure
or
- the septic tank floods due to groundwater leaking into the tank

Details are

at SEPTIC TANK INSPECTION PROCEDURE

Observing missing or damaged baffles at tank inlet or outlet are reason to figure we're ruining the drainfield.

Really? Always? No. Occasionally improper septic tank pumpout leaves a clogged septic tank inlet or outlet baffle.

3. Signs that the Problem is At the Septic Drainfield / Soakaway

IF the septic tank is being flooded and groundwater isn't leaking directly into the tank (by inspection)
THEN
there is either a blockage between tank and D-box (listed above at #2)
OR
the drainfield itself is in failure or flooded or has one or more significant blockages.

The plumber/septic contractor usually goes next to check at the D-box - if the box is flooded the drainfield is flooded; The d-box also gives access to try scoping the drainfield lines individually.

Scoping drainfield lines with a sewer cam or test excavation at the low-end of drainfield trenches can show flooding or other conditions there such as a thick bioifilm around the drainfield trenches (= end of life)

Details are at

SEPTIC DRAINFIELD FAILURE DIAGNOSIS

Also see

SEPTIC LEACH FIELD FAILURES - guide for home buyers & home sellers

Or to actually test the septic drainfield

see SEPTIC LOADING & DYE TEST PROCEDURE - home

On 2017-08-29 by (mod)

Readers note,

Septic system treatment chemicals are generally not needed, often ineffective, and depending on the chemistry, are illegal to use in many jurisdictions.

On 2017-08-29 by Kelsey Leroy

Hi

A drain field is a wastewater disposal system consisting of a series of perforated pipes laid along the bottom of trenches, connected to the outlet from a septic tank. renew a clogged septic leach field instead in mayflower chemicals and we also provided to all cleaning products available to online store

On 2017-02-08 - by (mod) -

Re-posting without advertisement

Kelsey Leroy said:
Hi

Drainfield is useful for wastewater treatment. Septic drains field are subsurface wastewater disposal facilities that remove contaminated and impurities of water. We also provide chemicals that can treatment wastewater.

Question / Comment:

(May 14, 2011) Timbo68 said:

This series of articles has been EXTREMELY helpful. I discovered some nasty water oozing out my yard. Research from these articles helped me to troubleshoot the problem and orchestrate and solution. Thank you SO MUCH!!

Question / Comment:

(July 22, 2011) ROBERT said:

WHAT SIZE OF PIPE WOULD YOU NEED ID YOU HAVE 200 GAL.A DAY WASTE WATER

Reply:

Robert 200 gallons a day of wastewater is very small - about one person's worth of use. But you want to be asking what size drainfield is needed, not pipe size (diameter);

The required drainfield size (feet of pipe in appropriately constructed trenches, for example) DEPENDS on soil conditions - if the soil has slow percolation rate you need more.

If the wastewater is gray water - sinks, tubs, laundry - an ordinary drywell might suffice.

Question / Comment: septic tank recently started backing up in the yard after lots of water usage indoors

(Aug 9, 2011) KZach said:

I have two concrete block septic tanks (a gravity system) at my home and both have been pumped in the last three months. My main septic tank recently started backing up in the yard after lots of water usage indoors (laundry, showers, etc).

We have also had a lot of rain recently. I know the septic tank backed up in the yard because the soil directly over the tank was wet and it smelled bad.

There was no backup in the house drains, however, the drains have been running slowly for the past few weeks and just before discovering the water in the yard I heard the toilet bubbling as I showered.

Since the tank was recently pumped, I would assume that it is not full.

I have a small pipe that I can open and view the water line into the septic tank from the house and it had evidence of scum in it and it has a constant water level filling about half of the pipe. The man that pumped the tank felt that the drain field was okay. He made no mention of the baffles.

Does this sound like a drain field problem? A problem with the baffles? An overloaded system? Thanks so much for your advice!

Reply:

Not quite KZach.

A septic tank (or a pair of them in your case) is normally ALWAYS FULL of septic effluent and sewage. In normal family use it takes just a few days for the tank to re-fill after being pumped.

The job of the tank is to retain solid sewage and perform partial treatment of the septic effluent - the liquid portion of wastewater. The effluent then flows out of the tank into a drainfield for further treatment by and disposal into the soil.

If your tanks are made of concrete block it sounds like a home-made system, maybe undersized septic tanks or leaky tanks that admit groundwater into the tanks during wet weather. If the tanks are flooding from groundwater that can saturate the drainfield too and lead to total system failure.

Some floating scum and settled sludge are normal in a septic tank. When those layers get too thick the septic tank stops working and sends sewage solids into (and ruins) the drainfield.

That's why we pump septic tanks on a schedule.

See SEPTIC TANK PUMPING SCHEDULE

Septic tanks MUST have baffles to keep solid waste out of the drainfield. OTherwise it's ruined. Your pumper should have looked at those components and would surely have told you if they were missing (common on home made septic tanks) or damaged.

IN sum, sewage backups in the yard and odors are a failure that needs diagnosis. Just pumping the tank won't fix that problem.

...

Continue reading  at SEPTIC FIELD FAILURE CAUSES or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• CLOGGED DRAIN DIAGNOSIS & REPAIR
• SEPTIC BIOMATS
• SEPTIC TANK & SYSTEM CARE BASICS
• SEPTIC DRAINFIELD INSPECTION & TEST - home
• PLUMBING DRAIN NOISE DIAGNOSIS.
• SEPTIC DISPOSAL FIELD CLOGGING INSPECTION
• SEPTIC DRAINFIELD FAILURE CAUSES
• SEPTIC DRAINFIELD FAILURE DIAGNOSIS
• SEPTIC LEACH FIELD FAILURES
• SEPTIC ODORS INDICATING DRAINFIELD FAILURE
• SEPTIC TANK GRASS or SNOWMELT
• SEPTIC TROUBLE SIGNS, OTHER
• SOAKBED SOIL CONDITIONS
• SEPTIC DRAINFIELD LIFE
• SEPTIC DRAINFIELD RESTORERS?
• SEPTIC LOADING & DYE TEST PROCEDURE - home

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SEPTIC DISPOSAL FIELD CLOGGING INSPECTION at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to SEPTIC SYSTEMS

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