EPA Sketch of an aerobic septic tank design using an aspirated mixer in the treatment tank Alternative Septic System FAQs
Questions & Answers about Septic systems for wet, steep, rocky, small, poor perc sites

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Guide to alternative septic system designs:

This article provides a master list (links at the "More Reading" links at the bottom of this article ) of all alternative septic system designs for difficult building sites such as wet sites, steep sites, rocky sites, limited space, bad soils with no percolation or sandy soils with too fast percolation, sites close to a lake, river or stream, and other difficult site conditions.

We provide detailed articles about each alternative septic system design choice, listing its features, design requirements, inspection details, maintenance needs, product sources. We include links to septic design engineers, advanced septic system products and septic design books and building codes. This document is a chapter provides in our Septic Systems Online Book.

Examples of advanced septic designs discussed in this article series include aerobic septic systems, chemical, composting, incinerating & waterless toilets, evaporation-transpiration (ET) septic systems, septic media filters, greywater systems, holding tank septic systems, mound septics, peat filter septics, raised bed septics, pressure dosing septic systems, sand bed filters, peat beds, constructed wetlands, wastewater lagoons, constructed wetlands, and septic disinfection systems.

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Alternative Septic System Design FAQs

Sketch of a Septic Mound System using a pumping stationQuestions and answers posted originally at SEPTIC SYSTEM DESIGN ALTERNATIVES - topic home.

On 2017-05-09 by (mod) re: what septic alternative design can be approved on a long narrow lot abutting a river?


There are small complete onsite wastewater treatment plants and alternative designs. But the place to start is with your local health or building department who approve septic designs, since there's not much value in even thinking about wastewater treatment systems or alternative design since if they won't accept it it's moot.

On 2017-05-09 by Catherine

Hi ,my property is on the river.sand rocks andboulders,I dug a hole and we didn't hit water till after 6 ft.the lot is 50 by 250 .that would be 50 ft of river frontage and 250 from the middle of the river to the road.its a flood plain and environmentally there hope for any kind of septic.

On 2017-04-12 by (mod) re: affect on number of bedrooms as a septic size requirement if you remove a closet


On occasion a building department might reconsider how removing or adding a closet will change how a building room is classified, but out of responsiblity to both the community and future owners of a property they may decide not to permit such changes.

On 2017-04-10 by Anne

It is my understanding that if we had not put a closet into one of the bedrooms it would not have counted as a "bedroom". Unfortunately, we have already installed the drain field and septic. We installed it in 2010 and have not yet used it because we are still working trying to save enough money to build our cabin with a small mortgage! While living in a rental here in town, I became active in the local neighborhood's effort to get playground equipment in an undeveloped park. WOW ! Do you know the first fall out from that effort?

Yep, you guessed it. The city sent out an "inspector" to check our well and septic system! No one lives on the property--there is no place except a falling down old cabin. The septic has not been used and the new well, which was installed the same summer, only gets used for drinking water when we are working on the place (got a little garden going and trails cut,etc.) The "inspector" announced that our name "came up randomly" to inspect. Yeah--sure you betcha ! :-)

Anyhow, after talking with him for a little bit he looked really chagrined and said that he had been brought in from out of state to help make sure new laws get enforced. Our djainfield, septic, and well were all permitted and constructed with all the proper permits in advance and passed all inspections at the time of completion !

After that visit I went to the city sewer plans office and the kid there tells me that even though the drainfield is huge, it has never been used therefore they needed to inspect it !

On 2017-04-08 by (mod) re: building department requires septic system capacity based on number of occupants who could or might occupy a building


Sounds like Holden Caufield strikes again - the Graduate.

Usually a building department requires that the septic system, including tank and drainfield, be sized to accomodate the number of people who COULD reasonably be expected to live in a home - often counting bedrooms for that purpose. They have to consider future occupants, not just two old retired fogies like you or me.

You MIGHT be permitted to connect a nearby structure to the existing septic system (tank) provided the tank is large enough, that there are not property line issues, and that your local building department approves. You'd need a septic engineer to specify that the system meets capacity and meets local codes.

Again, a designer cannot "care" that a property is used only once a year. The design for the septic system still must accomodate the maximum number of regular users. Otherwise, though used just one week or weekend a year, the cabin could still be expected to cause and experience a sewage backup or septic failure.

On 2017-04-08 by Anne

We were required to build a very large drainfield. There are only two of us (retired) and the gal who came out to approve/design the drain field had just graduated 3 weeks before ! She insisted that our drain field be large enough for 5 bedrooms 4 bathrooms--even though we showed her our design for 3 bedrooms 3 toilets. I would like to place a toilet in our new garage which is at the opposite end of the long drain field. Question: can I use the same drainfield and just install a septic tank and and the long line leading into the leach lines?

Our soil is glacial: fast draining sand with some spots of clay (5ft away). Even the slow draining clay came in under the required time. The area where the garage is is slightly higher in elevation and would provide could angle down to the leach fields. Any suggestion as to how to do this without putting the county into a fem/nazi breakdown ! ;-) We are in a rural area and the only house is brother's next door cabin about 100 feet away he has his own septic and drain field.

Their cabin gets used one weekend a year by about 6 people! They installed their drain field 25 years ago with a very small leach field about 10X12 feet ! No problems ! Hope you can help because we are in our 70's now and it is hard to be gardening up at the top of our lot and have to run down to the far end just to go to the toilet! Thank you for your time!

On 2017-02-25 by (mod) re: arguing with the building department about a septic design that doesn't meet the DOH specifications


We could spin a lot of wheels and more dollars when we ought to start by asking the APA and DOH what they will accept. For example there are plenty of lakefront properties that have installed acceptable septic systems by pumping uphill to a suitable distance away from the lake - and of course away from wells.

If your total site size can not meet those specifications then you might install an aboveground wastetreatment system whose discharge is certified to be cleaner than the lake etc.

On 2017-02-25 19:57:00.414356 by Timothy Russell

I have property on Cranberry Lake, New York and my engineer and I have been working the the Adirondack Park Agency (APA) and the New York State Department of Health (NYSDOH). I have been denied by both departments to install a septic system because I don't meet the APA requirements of being a 100' from the mean high water mark of the lake, and the I don't meet the NYSDOH requirements because I'm not 100' from by neighboring wells. Do you have any suggestions of what type of septic system I can install that will grant approval from these two departments? I purchased this property with a life time dream of owning a home on the lake, and now I faced with this delema. Thank you.

On 2017-01-30 15:22:18.137730 by Anonymous


On 2017-01-30 15:01:54.212816 by John

How do you fix lines that have broken away from the septic out in the yard. We have 2 very wet spots in the yard and feel they broken lines.

On 2016-11-05 00:09:35.442247 by Dennis Shumaker

Looking at a lot 9\10 of acre that owner thinks will not perk.Looking to build a 1500 to 1800 sq ft home with 3 bed rooms 2 full baths.Lot is narrow but deep.
What is a ball park cost for system and installed.
Location is keswick virgini ,near charlottesville va..
Thanks - dennis shumaker

On 2016-10-10 by (mod) re: Health Department approval of a drain field that is seasonally under water?

Jason, thanks for the important question. It's curious that a DOH would improve a leachfield that is seasonally wet as you can be completely assured that during that season the fields will not work: the bacterial processing of pathogens in the effluent will be impeded by lack of oxygen, there is an increased risk of transport of sewage contaminants to other water bodies, wells, etc., and there is increased risk of drainfield total failure, blockage, and sewage backup into the home.

Generally we want to see a couple of feet between the bottom of a drainfield or soakbed (leachfield) bed and the top of the seasonal high water table if we have any hope of a functional drainfield.

Cutting down trees makes sense: you cannot build a drainfield among trees without expecting a short life and destructive root invasion.
Torching weeds and planting grass is not harmful, but a wasted expense if done before the area is excavated for field installation.

You have several options including going to an advanced wastewater treatment system (search InspectApedia for those term), but the most common approaches (assuming there's no area to relocate the fields) include:

1. installing a curtain drain around the drainfield, draining groundwater to daylight well away from the fields - if terrain slope and shape permit

2. building up the soil level to give the clearance I describe - confirming what specifications will be accepted by your local health department, essentially building a MOUND SEPTIC SYSTEM or a RAISED BED SEPTIC SYSTEM - search for those terms to read details.

On 2016-10-10 by Jason C.

My leech field area was approved over 2 years ago. However, here in Indiana my leech field area is still too wet for the septic system installer to install my 4 100' long fingers. I have cut down trees, applied lime, blow large fans on the area, and cover the area with tarps during the rain, burned off the weeds with a torch, and now planted ryegrass on the area. The county health inspector comes out and digs 12" deep and says that its still too wet. Any ideas on how to get my soil dry at 12" deep?

On 2016-09-05 by knkar

is there a new system for plumping and sewage without having a septic bed system, we have land in nova scotia which is very rocky

On 2015-12-09 by (mod) re: buy or don't buy a home based on condition of the septic system?


The buy or not decision for property is not something that can nor should be answered based on a brief e-text. But it is reasonable to assume that the septic design for a property with poor percolation will involve extra cost such as for the design of a mound or raised bed or other alternative septic design. A more factual answer would be given by an onsite septic design engineer who can look at the property size, shape, location, and who knows what alternative designs your local building or health departments will accept.

On 2015-12-08 by Anonymous

We want to put an offer in on some land but the soil was tested and came back that there wasnt enough good soils for a drainage system. Would this involve bringing it dirt or going with a different alternative septic system??

Should we stay away from this land?

On 2015-11-17 by (mod) re: septic system designs for areas with a high water table

Good question, K.

You'll need an engineered septic, perhaps a mound or peat bed system that is raised sufficiently above the seasonally high water table (e.g. 2 ft - depending on regulations where you live).


On 2015-11-16 by Kafayat

How do we go about sewage treatment in a high water table area?

On 2015-09-18 by

We are just about to start planning a new build. Our existing septic tank was built 50 years ago and doesn't conform to regulations. The plot is mostly bedrock about 70cm below the ground. The house is 10 metres away from the septic tank and that doesn't give us 2 metres to the road. Any advice about the design we should go for, as there is no water course or room for a leech field.
Many thanks Eimear

On 2015-08-27 by (mod) re: how to enlarge septic drawings or illustrations at this website


Throughout you can click on virtually every image to see an enlarged, detailed version.

Question: Is there another system that will be approved to control liquid effluent retention?

I was interested in a piece of property which I understand that cannot accommodate sumping. I am under the impression (because I have not gotten to the end of figuring out why just yet) that this is because it is a waterfront property and/or the water table is too close to the surface thus reducing the availability of sufficient drainfield without causing water contamination. So my question is; is there another approved alternative to the absorption field to effectively control liquid effluent retention? - D.M. 8/29/2013


From your email I think you need an onsite septic design engineer - there sounds like a confusion of terms, codes, and requirements, and in my own case I'm not sure what you mean by "sumping" nor "liquid effluent retention" - those terms are not ones I use for onsite wastewater disposal.

If you are asking about a holding tank (sewage is retained and periodically pumped and removed by a waste hauler) some communities permit that design along a waterway but many do not.

If you are asking about how sewage and (separated) effluent are handled at wet sites, there are some designs that can handle that case, sometimes combining treatment above ground with disinfection; but again, not all communities will approve them.

That's why you need an onsite expert who also knows local codes & officials.

Some options you might want to discuss can be found in the article link I give just below. Also take a look at Anish Jantrania's book listed in the references section of that article. Dr. Jantrania has described wastewater treatment systems that can function effectively entirely above ground, producing sanitary wastewater discharge.

Question: explanation of septic drainfield soakbed layouts

(Mar 23, 2014) Rocky said:
i noticed that after my septic tank i come across a four way of orangeburg piping. it looks to me that the d box is layed out after this fourway. What would be the most logical explanation for this layout?



Indeed in a typical septic tank and drainfield or soakaway bed installation, a single line exits the septic tank and connects to a distribution box or D-box that in turn feeds two or more outlets of piping that are routed into drainage trenches, galleys, or whatever.

But I cannot guess at how your piping is laid out. If that's what you're asking you'd start by guessing by taking a look at the size and shape of the available drainfield area.

In a companion article

we show several typical drainfield layouts.

Question: find information about the Clivus Multrum composting toilet

(May 29, 2014) Anonymous said:
Went to Hawk Mnt,Allentown,Pa. Used an outdoor facility called, I belive clumus moltrom. Can you tell me about this and the correct spelling


Sure Anon, you're talking about a Clivus Multrum composting toilet discussed here at

Question: soil perc test results

(Oct 1, 2014) perne construction said:
We had a test boring done in the only place we can put a new cesspool and the results were Perched Water: 6'1" comment possible stream. Estimated Actual Ground Water Level 18' O +/-

My question is how and what kind of cesspool can be put in under these conditions



I would not install any kind of cesspool - as that approach to wastewater disposal does not effectively treat the effluent (not enough aerobic bacteria) and as cesspools are not permitted in new construction in most jurisdictions.

If your lot space is very small you may need an advanced wastewater treatment system, even an aboveground one such as Jantrania discusses. It's time to ask for help from a septic design engineer.

Question: design for septic systems over soil with high water table

20 January 2015 Susie said:
Im trying to get a septic permit for a property I gave an offer to. In 2002 it was denied due to "too shallow to water table". Is there any solution to this?


Susie you need

1. to find out what septic designs your local health department will approve, perhaps a raised bed septic or a mound septic design or another alternative design - see the designs including the two I cite at More Reading above listed under SEPTIC SYSTEM DESIGN ALTERNATIVES

2. to find a local septic design engineer who understands local soil conditions as well as what the building department finds comfortable among various designs

Keep us posted

Question: Can a homeowner be trained to do the maintenance on the ATT systems

(Feb 8, 2015) Diane said:
Can a homeowner be trained to do the maintenance on the ATT systems so not to be spending thousands every 2 years on a required maintenance agreement to some septic company who gets warnings over the phone line?



Certainly there are septic system maintenance procedures that a homeowner can do such as changing filters and - WITH CAUTION as you could die - if there is an access port to inspect the septic tank level a homeowner can certainly look therein to see if levels are normal. And for systems that use pumps or areators an owner can and should learn to know if the equipment is running.

The hazards that can be fatal are leaning over a septic tank opening (overcome by fumes), working alone, or entering a septic tank (NEVER do that).

If you know the design, equipment brands, etc. of your system together we should be able to undertand what's installed and which tasks an owner can and should perform.

(Feb 12, 2015) Diane said:
Thank you Dan. Understand the cautions you mention and appreciate the list. No plan on entering the tank...ever. Planning for future needs and some requirements I was told in maintenance agreements cost a fortune and seemed easy for a home owner to do and assure a good working system....that is affordable.


Don't hesitate to ask us if specific septic system maintenance or care questions arise. Indeed studies by Small Flows and other expert sources have repeatedly indicated that the number one factor in early failure of septic systems is that owners ignore the system maintenance requirements.


Continue reading at SEPTIC SYSTEM DESIGN ALTERNATIVES - home, or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.




Or see TYPES OF SEPTIC SYSTEMS - master list

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