This document explains what a drywell or seepage pit is, gives safety and maintenance advice for drywells / seepage pits, and defines the criteria for drywell failure.

We also explain a useful difference between a drywell (accepts only graywater) and a seepage pit (accepts septic effluent).

We warn readers that while installation of a drywell to receive graywater at a property may be a good idea, the use of drywells may be a warning about the capacity and remaining life of the septic system.

This article series explains septic system and drywell or seepage pit or cesspool inspection procedures, defects in onsite waste disposal systems, septic tank problems, septic drainfield problems, checklists of system components and things to ask. Drywell & seepage pit maintenance and pumping schedules.

Guide Seepage Pits: definitions, construction, testing, uses, warnings

Seepage pits: a "seepage pit" may be used as a septic effluent absorption system such as shown in the sketch at the top of the page and also immediately above.

In this application, instead of receiving only graywater from sinks, laundry, shower, etc., the seepage pit is receiving not just graywater but also blackwater-effluent or septic effluent which flows out of a septic tank.

Seepage pit design specifications: this article discusses the design & construction of septic seepage pits for septic wastewater treatment to perform the functions of septic effluent treatment and disposal in onsite wastewater treatment systems, conventionally called "septic systems".

A seepage pit is designed to receive clarified effluent from a septic tank, or if the pit receives only graywater wate then it's called a drywell.

See details at DRYWELL DESIGN & USES

Unlike the drywell described just above, in this septic effluent waste disposal, including black water and gray water, wastewater leaves the building through a main drain which enters a septic tank. The septic tank retains solids and grease/floating scum, allowing clarified effluent to enter the seepage pit for disposal into the soil.

Distinctions among cesspool, cistern, drywell & seepage pit:

• Definition of Cesspool:
  
  a hole in the ground, lined with site built or manufactured perforated sides / bottom that receives raw sewge, blackwater, including solids and liquids, allowing effluent to seep out of the cesspool into surrounding soils. There is no separate effluent disposal system.
• Definition of Cistern:
  
  a holding tank above or below ground used for storing clean water for drinking or other uses
• Definition of Drywell:
  
  a hole in the ground, lined with site built or manufactured perforated sides / bottom that receives graywater or other non-sewage water such as roof drainage
• Definition of Seepage pit:
  
  a hole in the ground, lined with site built or manufactured perforated sides / bottom that receives liquids only (i.e. not a cesspool). In our usage, a seepage pit receives septic effluent from a separate septic tank, while a drywell receives graywater or other non-septic drainage waters directly from their source.
  
  We perfer to distinguish between these two applications because depending on how a seepage pit is being used, its design, capacity, life and maintenance may be different. But many other texts use the terms drywell and seepage pit as synonyms.

Seepage pits come in a variety of capacities, sizes, shapes, and can be safe (against collapse) when a modern factory-built unit is shown, such as those in this photo.

Watch out: We do not consider the use of traditional seepage pits a complete and satisfactory onsite septic effluent wastewater disposal system design, though where space is limited or for other problem site reasons it may have been the choice of the septic system installer.

Disposal of septic effluent deep below ground in a seepage pit (typically four to six feet deep and placed another two or more feet below grade level) means that little or no aerobic bacteria will be present.

Limiting the bacterial action to anaerobic may mean that the biomat that forms around the seepage pit will not adequately treat the effluent. The system may then be discharging contaminants into groundwater and the environment.

Fortunately there are alternative onsite wastewater disposal alternative designs which can handle limited or even zero-space sites, so a simple seepage pit as a destination for blackwater effluent is no longer the only choice for limited-space sites.

More Reading about Seepage Pits for Septic Effluent Disposal

(h) Seepage Pits used for septic system effluent disposal in "New York State Septic System Design Regulations 75-A.8 Subsurface treatment - disposal of septic effluent - design specifications for septic systems" includes design specifications for seepage pits used to receive septic effluent, including tables of dimensions required for different household loads.

Drywell and Seepage Pit Safety and Septic System Capacity Warnings

Drywell & Seepage Pit Safety

• Watch out:  Safety Warning: do not walk over the top of or close to the edges of a drywell or any other onsite pit or excavation because of the danger of fatal collapse. Keep pets and children away from such systems.
• Watch out:  Safety Warning: there is a risk of drywell collapse, risking injury and potential fatality if someone falls in to one of these systems, particularly for older site-built systems that were often made of dry-stacked stone or concrete block, and more-so if such systems are not protected by a very secure cover.
  
  Believe it or not, simple wood board covers were often used on home-made drywells. Such covers rot and ultimately collapse.
• Watch out: Readers trying to diagnose and deal with sudden soil subsidence or yard collapses should
  
  see CESSPOOL SAFETY WARNINGS as those hazards can also apply to drywells and septic tanks.

Drywell & Seepage Pit Capacity and Testing Limitations

• Limited septic system capacity
  
   implied by the presence of a seepage pit. Wet soil conditions or limited space for a functioning drain field (for the septic system) often leads property owners to reduce the liquid load on the septic system by routing gray water to a separate drywell.
  
  Where such a system is installed owners/buyers should be alert for these conditions and should expect to face extra costs for system maintenance and repair as well as limited septic system capacity.
• An exception to the septic system capacity warning
  
  above at a large building where a sink or laundry are added in an area distant from piping connected to the septic system, an owner may add a remote drywell as an alternative to inconvenient and costly routing of a drain line from the laundry to the existing septic system.
• Septic system test warning:
  
  the use of seepage pits (or drywells) can obscure or prevent effective septic loading and dye testing:
  
  If a drywell system is installed, running water at the fixtures draining into this system (as may be done by some septic tests) are likely to fail to perform a loading test on the septic system even if such a test was attempted.
  
  First, the fixtures where water was run in attempt to test the septic system (tank and leach field) may not even be delivering water to those components if instead the fixtures drain to a separate drywell. It is critical to trace building drains as part of a septic test or to otherwise try to determine if the test water is actually entering the septic system.
  
  Even if we're trying to "test the drywell or seepage pit",
  
  if the seepage pit is "working" at all, it is a large, mostly empty hole in the ground.
  
  After a period of disuse it may appear to be working during a test because the "test" is simply filling up the empty hole in the ground. But if soils around the seepage pit (or drywell for that matter) have become clogged, the system will fail in a day or two of ordinary use as the no-longer functioning hole is filled with wastewater.
  
  Where a drywell or seepage pit is installed at a property and a septic inspection was attempted, more testing may be in order: in cases where only toilets empty into the septic system, it may be possible to make a more effective septic loading and dye test: put a test water load directly into the toilet by using a garden hose.
  
  This is not a typical/normal septic test procedure and has its own concerns such as overloading a system of unknown design that did not anticipate such volumes and possible back-contamination of water supply via hose in toilet (a cross connection).
  
  Whether or not such an additional test is performed, our warning about a system of limited capacity for which the owner may face significant costs to repair or expand capacity remains in effect.

Tips for Extending Seepage Pit Life Life

Some experts recommend installing a filter on water entering the seepage pit.

Particularly for a seepage pit used to receive water not just from a septic tank receiving black water but also graywater from a clothes washing machine, installing a lint filter between the washing machine and the seepage pit can extend the life of the drywell by reducing the moment of soil-clogging particles of lint and debris into the system.

Intermittent dosing systems such as are used for some alternative septic system designs, can also be adapted to graywater systems. In simple terms, this means that multiple drywells are used, and graywater is routed intermittently among them, giving the unused drywell time to recover. A

simple valve system on the graywater drain line can serve to route greywater (graywater) to alternating drywells.

• CESSPOOLS [separate article] gives more in-depth information about those systems.

Seepage Pits - Seepage Pits used for septic system effluent disposal

Repeating an important distinction we made above, a cesspool is not a seepage pit, and vice versa, though their construction may be similar.

Cesspools receive black water (sewage including solids) directly.

Seepage pits receive only clarified septic effluent ( no large solids).

(1) General notes about seepage pit septic system components

A seepage pit, sometimes called a leaching pit, leaching pool, or incorrectly a cesspool, is a covered pit with an open-jointed or perforated lining through which septic tank effluent seeps into the surrounding soil.

[DF NOTE: the term drywell might be used for a seepage pit disposing of septic effluent in this case; by contrast, a cesspool holds both solid waste and septic effluent.

I use the term "seepage pit" to refer to a pit used to dispose of septic effluent which originated as blackwater, the solids having been retained in the septic tank.

I use the term "drywell" to refer to a pit used to dispose of graywater (greywater) which originated in sinks, laundry facilities, or showers. While their uses and implications of their presence at a property are quite different, the actual construction details of a seepage pit or a drywell are about the same.

• DRYWELL DESIGN & USES (our main page on this topic) for more in-depth information about seepage pit and drywell systems.
  
  Seepage pits and drywells are discussed in greater depth and are contrasted with cesspools or onsite gray water disposal - What are Drywells, What Drywell Maintenance is Needed? How do Drywells Fail?
• CESSPOOLS provides more in-depth information about those systems.

(2) Site Requirements for septic seepage pits

(i) If soil and site conditions are adequate for absorption trenches, seepage pits shall not be used.

(ii) A minimum three foot vertical separation must exist between the bottom of any pit and the high groundwater level, bedrock, or other impervious layer.

(3) Design Criteria for seepage pits used to dispose of septic effluent

(i) The required "effective seepage pit area" is obtained from Tables 6 and 7 which are shown below.

(ii) No allowance for infiltration area is made for the bottom area of a pit or the surface area of impervious soil layers (percolation rate slower than 60 minutes/inch).

(iii) The effective diameter of a pit includes the diameter of the lining plus the added diameter provided by the annular ring of aggregate. Any area surrounding the liner with rock smaller than 2 1/2 inches in size shall not be included as part of the effective diameter.

(iv) Effective depth is measured from the invert of the seepage pit inlet to the floor of the pit, with the thickness of impervious layers deducted.

Site Distance Requirements for Seepage Pits

This sketch (from New York's Wastewater Regulations) shows the recommended site clearances between a seepage pit (or cesspool or drywell) and other building and site features.

A more detailed list of site clearances to septic system components is listed at "More Reading" just below. Notice that seepage pits not only need to be at a sufficient distance from the building, from wells, from property lines, but also if multiple seepage pits are installed, they should be adequately separated from one another.

• CLEARANCE DISTANCES for Septic Components Required - Well distance to Septic, Septic clearance from well, trees, lakes, streams, property boundary, etc.
  
  
• 75-A.0 New York State REGULATION of PRIVATE SEPTIC SYSTEMS

Absorption Area Requirements for Seepage Pits

Table 6 shown here gives the required soil absorption area for seepage pits as a function of soil percolation rate and anticipated daily wastewater flow in gallons.

[Click to see an enlarged, detailed version of this or any other image or table found at InspectApedia.com]

TABLE 6 - SEEPAGE PITS - REQUIRED ABSORPTIVE AREA (IN SQUARE FEET) FOR HOUSEHOLD SYSTEMS

Seepage Pit Size Requirements to Obtain Necessary Absorption Area

Table 7 given below shows the size of seepage pit necessary in order to provide the required soil absorption area for seepage pits. First use the preceding table to determine the necessary seepage pit absorption area, then use this table (below) to determine the necessary seepage pit size to provide that absorption area.

TABLE 7 - SEEPAGE PITS (CYLINDRICAL) - DIMENSIONS FOR REQUIRED ABSORPTIVE AREA (IN SQUARE FEET)

Seepage Pit Construction Details: Linings, Separation, Strength, Connections

The schematic of a seepage pit (left, courtesy USDA) shows typical construction of a site built seepage pit using brick, block, or pre-cast concrete rings with open joints, surrounded by stone to improve soil absorption.

NYS:

(v) Seepage pit linings

may be pre cast concrete, cast-in-place concrete, or built in place with unmortared hollow cinder or concrete blocks. Concrete shall have a minimum compressive strength of 2,500 psi and 3,000 psi is recommended.

Material with comparable structural strength, determined in accordance with commonly accepted sewage construction standards, principles or practices, may be allowed on an individual basis to prevent unreasonable hardship, provided public health is not prejudiced.

(vi) The separation between the outside edges of seepage pits

shall be three times the effective diameter of the largest pit. This separation is measured as the undisturbed soil between pit excavations.

(vii) Pits shall be designed with sufficient structural stability

to withstand lateral soil forces as well as vertical loads.

(4) Construction of seepage pits for septic effluent disposal

(i) Laterals leading to each seepage pit

must be at least four inches in diameter with a minimum slope of 1/8 inch per foot.

(ii) Seepage pits shall not be connected in series.

A distribution box shall be required where more than one seepage pit is installed.

(iii) The pit excavation is to be raked

to minimize sidewall smearing that may occur and reduce infiltration capacity. If groundwater is encountered, the pit shall be backfilled with the original soil to a level at least three feet higher than maximum groundwater and adjustments made in the pit dimensions.

(iv) The linings are placed upon a concrete block, poured concrete, or pre cast footing

and surrounded by a six inch minimum annular ring of large aggregate (2 1/12 - 4 inches in size).

(v) The rock is covered

to prevent soil from filling the void spaces. Building paper, a four inch thick layer of hay or straw may be used.

(vi) The seepage pit cover

shall be structurally sound and capable of supporting 300 pounds per square foot at the weakest point.

Covers may be pre cast concrete or cast-in-place and shall be reinforced. A manhole with an opening of at least 20 inches in the shortest dimension shall be provided.

Septic Seepage Pit, Drywell, or Cesspool Collapses

A seepage pit, drywell, or cesspool can be collapsed as shown in this photo, where a seepage pit receiving septic effluent was driven over by a heavy dump truck.

Watch out: Seepage pit, cesspool, or drywell collapses are dangerous and can be fatal if someone falls into the collapsing opening.

Falling into a cesspool, seepage pit, or drywell can easily be fatal, and quickly. We investigated a tragic case in which an adult fell into a cesspool that then collapsed over him, burying him alive.

In general, while there are heavy duty septic system components and covers for pits and tanks, you should not permit traffic to drive over septic equipment nor on septic fields.

See SEPTIC & CESSPOOL SAFETY.

Seepage Pit Life Expectancy & Maintenance

Reader Question: What product can I by that will eat the grit and dirt off the walls of the seepage pit, clean the pores so that the liquids will drain out in the earth, and so that I do not have to pump out all the time?

I live in the Hollywood Hills CA. I have a septic tank inlet and outlet and a seepage pit. My seepage pit & septic I have to have to pump out every 4 months versus 2 years, for the liquids are not seeping out and the pores are clogged with grit, dirt and I would say toilet paper.

What product can I buy that will eat the grit and dirt off the walls of the seepage pit, clean the pores so that the liquids will drain out in the earth, and so that I do not have to pump out all the time? - S.B.

Reply: Sounds As If You Need a New Seepage Pit

A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a septic system or seepage pit problem.

That said, we do not recommend septic seepage pit additives

 or cleaners for septic effluent seepage pits - using at least some of these products risks contamination of your environment, groundwater, or nearby wells, and depending on local laws septic treatment chemicals may be illegal as well.

See details at SEPTIC TREATMENTS & CHEMICALS

Septic seepage pit rejuvenation methods 

like agitating or hydrojetting can sometimes temporarily give some relief and cause drainage at least from the bottom of the pit, but depending on how the seepage pit has been constructed these methods can be very dangerous. The risk is a pit collapse, someone can fall in - a fatality that has actually happened more than once.

In sum if the seepage pit no longer drains into the surrounding soils, you need a new one.

You can extend the connection to the new seepage pit from an outlet from the old seepage pit provided the old pit is not in danger of collapse.

Otherwise the old pit needs to be abandoned: pumped out and filled-in with soil and rock to be safe.

Your observation of toilet paper in the seepage pit 

suggests that solids are not being retained in the septic tank where they belong.

If solids are flowing into the seepage pit from the septic tank, that will explain its short life and costly frequent pumping.

The cause could be damaged or missing baffles in the septic tank - something that can be repaired when your new seepage pit is installed.

Our photo (above-left) shows a damaged septic tank baffle that was allowing solid waste to flow out of the septic tank into the absorption system.

Details of septic tank tee replacement (baffle replacement) are

at SEPTIC TANK TEES.

When your new effluent seepage pit is being installed,

look into installing a filter at the outlet from your septic tank; in fact check that the septic tank baffles are intact.

Beyond their design specifications provided here, seepage pits & drywells are also discussed and are contrasted with cesspools

at DRYWELL DESIGN & USES or onsite gray water disposal - What are Drywells, What Drywell Maintenance is Needed? How do Drywells Fail?

A cesspool is not a seepage pit, and vice versa, though their construction may be similar. Cesspools receive black water (sewage) directly.

Seepage Pit Regulations & Designs

• New York State Department of Health, APPENDIX 75-A WASTEWATER TREATMENT STANDARDS - INDIVIDUAL HOUSEHOLD SYSTEMS , [PDF] New York State Department of Health, 3 February 2010, retrieved 3/1/2010, original source: https://www.health.ny.gov/regulations/nycrr/title_10/part_75/appendix_75-a.htm
• Pennsylvania State Wastewater Treatment Fact Sheet SW-161, Septic System Failure: Diagnosis and Treatment
• Pennsylvania State Wastewater Treatment Fact Sheet SW-162, The Soil Media and the Percolation Test
• Pennsylvania State Wastewater Treatment Fact Sheet SW-l64, Mound Systems for Wastewater Treatment
• Pennsylvania State Wastewater Treatment Fact Sheet SW-165, Septic Tank-Soil Absorption Systems
• Septic Tank/Soil-Absorption Systems: How to Operate & Maintain [ copy on file as /septic/Septic_Operation_USDA.pdf ] - , Equipment Tips, U.S. Department of Agriculture, 8271 1302, 7100 Engineering, 2300 Recreation, September 1982, web search 08/28/2010, original source: fs.fed.us/t-d/pubs/pdfimage/82711302.pdf
• U.S. EPA, SEEPAGE PITS MAY ENDANGER GROUND WATER QUALITY [PDF] (2001) United States Environmental Protection Agency, US EPA, - retrieved 2023/12/05, original source: epa.gov/sites/default/files/2015-06/documents/seepagepits.pdf
  
  Excerpt:
  While the use of cesspools for sewage disposal has been prohibited in most states for a number of years, some local ordinances still allow for the construction of drywells as a means of dispersing effluent from septic tanks.
  
  When used in this fashion, they are more commonly called “seepage pits.” This method of effluent dispersal is deficient for a number of reasons:
  
  1. Seepage pits disperse effluent in anoxic, or oxygen-poor, environments, where pathogens (especially viruses) may not be treated before they reach the water table.
  
  They place fluids below the root zone, where there is no immediate uptake by plants of the water and nutrients, nor is there the potential for treatment by evaporation or evapotranspiration.
  
  [See the document for the remaining concerns about seepage pits and cesspools]

 

 

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Limitations of installing seepage pits on steep slopes

My county says the seepage pit can only be installed on slopes of 30% or less. Could you please explain how is the slope measured (what distance and direction from the pit) - On 2019-04-27 by Cristina -

Reply by (mod)

Christina I assume your county authorities are talking about the area where the seepage pit itself is installed as well as some minimum area, perhaps just a few feet (but maybe more) around the pit - they are concerned that on a steeper slope the effluent won't soak away down into the soil but rather it'll break out and run to the surface, down-slope from the pit.

Just how much soil you'd need around a seepage pit on a slope to avoid break-out of wastewater depends on a number of variables such as the soil properties - how porous is the soil, and probably the wastewater volume and seepage pit size and construction.

You need to ask your county how much low-slope area (under 30% slope) they want to see for your county or for your specific site and soil properties.

See details of the math at CONVERT PERCENT GRADE to ANGLE or SLOPE

Example: if the soil slopes from an uphill starting point down 30 feet across 100 feet of horizontal distance that would be a 30% slope.

Remember that to measure the horizontal distance that measuring line must be kept level or "flat"

So in the sketch given here I point out below if vertical distance (c) is 30 feet and horizontal distance (b) is 100 feet then that's a 30% slope or grade.

 

On 2021-05-05 by Septic Pit - tree crushed pipe between septic tank & seepage pit

I recently replaced some 4" Pipe that leads from my septic tank to the Septic Pit, a tree had grown on top and crushed the pipe.

When I place a camera down the pipe going down into the septic pit it goes about 15 feet down and then gets stopped.

The pipe looks clear all the way until this point. Should I assume this is the bottom of the pipe and the camera is hitting the end cap?

Reply by (mod)

@Septic Pit,

I think we are discussing a septic seepage pit. There is no end cap on the bottom of a seepage pit. It's open to the soil. Typically a hole is dug and gravel is put in the hole and then the pre-cast concrete seepage pit is placed in the hole. Or of course it may be constructed of other materials.

Soil around seepage pits of cesdpools or drywell pits eventually becomes clogged with a biofilm and sewage sludge.

At that point seepage pit is no longer functional and will need replacement.

Watch out: working around a seepage pit is dangerous. And unsafe cover or flimsy construction of the pit means that you could fall in which results in an instant and horrible death.

If you don't know the construction of the pit and its condition and those if you can't be certain that the cover and pit are safe, you should keep away and keep others away and have it explored by a professional excavator

On 2020-09-18 by Dennis Can I maintain my seepage pit using Draino or CLR?

What is the best way to maintain a SEEPAGE PIT.?

To keep the gray water flowing into it, etc. Is it okay to treat it with CLR or Draino? etc.
Thanks in advance

Reply by (mod) -

Dennis

No additive will fix a seepage pit, and they are generally illegal in most jurisdictions, and some of them are serious environmental contaminants. Don't do it.

Unfortunately once a seepage pit has stopped absorbing effluent the steps experts take are limited to

1. Jetting or probing the seepage pit bottom and in some constructions sides: this can be VERY dangerous and has led to some fatalities as the treatment can cause some seepage pits to collapse; even when this works it's short-lived. DON'T DO IT if your seepage pit is home-made out of stacked block or rubble;

2. Building a new seepage pit that often is daisy-chained to the old one so that waste that begins to fill the old one flows into the new pit; This is what I've done at several properties;

The cost to partially dig up the sides of a failed seepage pit is as much or more (as it's tricky) than to simply build a new pit.

Of course, as with many troublesome and costly problems the failed drywell or seepage pit or cesspool topic has bred an industry of magic bullets that don't work, don't last, and/or are illegal. I'd take care.

 

On 2020-03-27 by Christopher Hazell - How do I find the seepage pit cover to empty it out?

How do I access my seepage tank for my septic tank service to empty it out? Is there a lid on the top to access? Waiting patiently on your reply? Thank You

I recently had my septic tank emptied which I do every 1-2 years. I am having some issues with my seepage tank and want to get that emptied as well. How to I get access for my sewer company to do that? - Anonymous

On 2020-03-28 - by (mod) -

Chris,

Yes it's common for seepage pits to have a removable cover for inspection.

Watch out: Be sure to read the notes in the article above and the comments below. There are very serious Life Safety hazards when the condition of a seepage pit is unknown, because when you start to ffool with it, you could fall in, which can be instantly fatal.

Never work alone.

Don't empty the seepage pit.

Anonymous:

"Seepage tank?" What's installed at your home: conventional (water tight) septic tank draining into one or more seepage pits?

If so, while you can try to rejuvenate the seepage pit, usually when it's filling up you know it's time for a new one. Not to mention that seepage pits don't treat the effluent, so we're basically sending pathogens into the surrounding soil, waterways, wells.

That's why in most jurisdictions the health department or code officials will want to see a real drainfield or mound or other working effluent disposal system installed.

Therefore before spending on your seepage tank, let's understand what's installed, how it was constructed (what materials), what is its condition, what space is available for a proper septic system and what local officials will permit where you live.

On 2020-03-28 by Christopher Hazell - Should I have my seepage pit emptied out like the septic tank?

Do you recommend having them emptied out as well as my septic tank? I empty my septic every 1-2 years but was unaware I had a seepage tank and never emptied that out. I have a scheduled service to empty it this week. Do you feel good idea?

On 2020-03-29 - by (mod) - NO: we do not recommend pumping out or "emptying" seepage pits or cesspools

Christopher


I do not recommend pumping out or "emptying" seepage pits or cesspools in general because

1. The seepage pit is already at end of life: if the pit is filling then it is near end of life as the surrounding soil is clogging with biomat -
See details at

CESSPOOL FAILURE CRITERIA https://inspectapedia.com/septic/Cesspool_Failure.php

2. Seepage pit & cesspool rejuvenation provides little benefit: while jetting can temporarily extend the life of a cesspool it's only temporary and worse

3. Watch out: jetting cesspools and seepage pits is dangerous: depending on the cesspool or seepage pit construction methods and materials there is danger of causing a complete collapse of the system - an event that has on occasion caused death of people nearby falling into the pit.

See details at CESSPOOL SAFETY WARNINGS https://inspectapedia.com/septic/Cesspool_Safety.php

On 2019-07-01 by Rick F - The home inspector assumed our guest cottage was connected to the septic: it's not but we don't understand what is installed

general question.
when we bought our 30+ year old house in the southern Nevada desert the property had a guest house behind the main house which the realtor and home inspector assumed was properly connected to the main septic.

at a corner of the property was a pad for an RV with waste drain hookup. we never used the later. recently someone drove the lawn tractor over the area the drain pipe for the RV and collapsed the tank below it. yesterday the waste line from the casita backed up and we assumed tree roots and dug up the line at about the point the snake hit a block. found something strange instead.

This is the question, what am I looking at? Anybody identify the system as anything other than a back
country enginneered attempt at waste disposal?

At both locations we dug up an approximately 2'x4' by 1.5 ' deep metal box with the drain going into it. each about 100gal volume and surrounded by about 12 inches of 2 inch gravel on the sides. depth unknown. from the remains of one cover looks like it was meant to collect solids and 'weep' over the top lip below the cover into the gravel.

Entire thing covered in plastic then backfilled with dirt. no apparent connection to the real septic tank. The RV tank was empty and dry so easy to examine, steel box rusting away lid collapsed. the guest house full of sludge.

Ok, I assume these are not legal, at least anymore. look like a hybrid of a grease trap and seepage pit with the trap placed directly on top of the pit.h ouse built around 1975. guest house coverted from garage about 1985. I'll guess these went in about then.

Since the boxes look manufactured maybe they were once a commercial product and I would love it if someone knew what they were and what kind of a septic system this was meant to be.

BTW they are not going back in.

After checking depth and grade of the house sewer line back to the drain on the guest house the only reason I can see they were not connected was a previous owner was just to lazy to dig a 75' trench and do it right. Somehow digging a pit was a better option?

On 2019-07-02 - by (mod) -

Rick,

I understand a realtor - bound to sell the property - making optimistic assumptions, but a home inspector? Who recommended that person? Realtor?

Small metal boxes sound like home made seepage pits that frankly cannot possibly work for very long - volume too small, probably not a durable material. I suspect they were never "legal".

About lazy owner and 75 ft. trench, keep the elevations in mind. At 1/8" / ft. there could have been a depth issue at the receiving end.

I think you intended to include a photo but don't see one. You can use the add image button.

On 2019-05-02 by Cathu - How long can a septic tank with two seepage pits last?

How long can a septic tank with 2 seepage pits last? We are buying a house with a 60 year old system.

On 2019-05-02 - by (mod) -

Cath

In the INDEX to RELATED ARTICLES found at the end of this article you'll find SEPTIC LIFE EXPECTANCY 

Depends on the tank material and other factors.

I suspect you want to ask about seepage pit life.

At 60 years old, zero predictable life remaining

You'll also want to read

DRYWELL / SEEPAGE PIT COLLAPSE or FAILURE 

Watch out: an old seepage pit of unknown condition could lack a safe cover: falling in usually means a quick and nasty death.

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Suggested citation for this web page

SEEPAGE PITS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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INDEX to RELATED ARTICLES: ARTICLE INDEX to SEPTIC SYSTEMS

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Citations & References

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