These questions and answers about how to figure the size of large capacity or commercial septic tanks and wastewater systems can help point you in the right direction.

This article series describes the basic design approach to commercial wastewater treatment systems: how big should the septic tank be and how large should the drainfield be for non-residential installations like hotels, restaurants, gas stations, parks?

FAQs on Septic Tank Design & Size for non-residential wastewater disposal systems

These questions and answers about commercial septic systems and septic tank sizes & designs were posted originally

at COMMERCIAL SEPTIC DESIGN - home - please be sure to review the advice given there.

On 2021-04-13 by (mod) - What size septic drainfield will be needed for a small RV park with 15 sites and 2 restrooms?

@Small 30 Site RV Park,

Thank you - You're asking good questions but not ones that anyone can nor should guess-at by a brief text inquiry.

An onsite septic engineer would look at the soil percolation rate to tell you how many feet of what type of absorption bed or trenches or chambers (not so reliable) you need.

A 3,200 gallon septic tank can support up to 2,500 gallons of wastewater a day. On that basis if your calculations are right, the tank is big enough. But I would re-visit the assumption of just 50 gallons of wastewater per day per hook-up site and add to that an estimate of wastewater from your restrooms, showers, etc.

Most people will use more than 50 gallons of water a day;

see WATER QUANTITY USAGE TABLES

But you could make an interesting calculation:

Take a look at the maximum RV size that you host and the maximum RV freshwater storage tank size and then at your own data on length of stay of your visitors and the frequency with which they fill-up their RV holding tanks. I've read assertions that an owner of a 35 ft RV carrying a 100 gallon supply of fresh water makes that last a week. That's just a little over 14 gallons a day.

An RV's freshwater tank size ranges from about 20 to 100 gallons depending on RV size. -various sources including https://camperreport.com/how-many-gallons-of-water-does-an-rv-usually-hold/The RV graywater tank in a typical RV might be just 30-40 gallons and blackwater tank about the same (and is emptied less-often than graywater tank)

Some RV publications say that RV'ers use very little water, perhaps 2-5 gallons per person per day - at least when NOT connected to a water supply hookup, but probably more when they're hooked up to a water supply; that'd support your assumption.

Some sources that looked more-realistic to me put the water consumption rate higher, at about half the at-home daily water usage, putting it (by my data) at 20-30 gallons/day) https://goodoldrvs.ning.com/profiles/blogs/water-usage-comparison

https://rvlife.com/daily-water-usage/ has a water usage determination page but offers no data, just usage measurement ideas.

https://musingsonentropy.com/2014/10/07/motorhome-living-one-month-in-daily-water-consumption/ has one opinion/reader describing using about 6-7 gallons a day per person (graywater).

Tell me, if you have it, your known fresh water consumption per hookup site per season and the number of season-days and we can get an average.

Also, we need to separate and report dumping of graywater vs dumping of blackwater as often those are in separate reservoir tanks and are accumulated and emptied at different frequencies - graywater more frequently than blackwater (sewage).

Remember the septic system has to be able to handle peak loads, not just the average load.

On 2021-04-12 by Small 30 Site RV Park

Our drain field seems to be failing and we would like to replace it. We have a small RV park with a 3,200 gallon septic tank and three (known) 90 foot drain field lines (dome style) and one 40 foot drain field line.

My calculations are, if ALL of our 15 Full Hook-Up sites (sewer at the site) AND ALL of our 15 Partial Hook-Up sites (which have to pull up to the Dump Station to dump) dump each day, that is a total of 30 sites dumping X 50 gallons = 1,500 gallons a day. We also have 2 restrooms with 2 sinks, 2 showers and 2 toilets in each. Our soil is somewhat sandy with some rocks.

1. Is this max load Per DAY sufficient for our tank size?
AND
2. If we replace the drain field, how many 4" lines (up to 90'-100' each) would we need to adequately meet our needs? Thanks.

On 2020-06-14 - by (mod) -

Vicki

Sorry to say, a conventional septic tank that's under 1000 gallons is too small even for a typical single family home by modern standards. That's probably why your Council is pushing you to have an evaluation - so someone else can tell you the bad news.

The problem is that with high wastewater flow volume the too-small septic tank doesn't have enough time for solids to settle out of the effluent - instead they're pushed into the absorption system, shortening its life or discharging pathogens into the enviornment.

See if you can get a local septic engineer to give you some basic design points.

Let me know what you're told and we may be able to offer some suggestions.

On 2020-06-11 by Vicki

I did post this on the other page, but I think this is the correct page to do so...

I am trying to get someone who can give me an answer to the following:

We have a Cafe which has been in business for 12 years.
We are trying to extend our hours, and for this reason council are demanding a complete new assessment on the septic system.
It has coped with 50-100 customers per day without any problems and often far more.
A whole new assessment will cost thousands.

I just need to know this:
We have a 3000L (793 Gallons) septic tank with biological effluent filter on the outlet, plus an internal effluent filter.
We have 3 evaporations-transpiration/absorption beds, each one being 20m x 2m ( 65.5 x 6.5 feet) and there is a 2m (6.5 foot) gap between each row.
In Australia, 15L (3.9 gallons) is acceptable per customer/per day.

With this size tank etc. what would be the maximum number of customers per day the system could handle?
Can anyone please help?

Thanks in advance

On 2020-02-27 - by (mod) -

Carol,

Thanks for an important question: how to size a dosing tank for septic systems. There's not, however a single "right" answer since there are several types of septic systems that use an effluent dosing method.

Please take a look at the septic dosing system designs found at

GRAVITY/SIPHON DOSING SYSTEMS https://inspectapedia.com/septic/Gravity_Dosing_Septic_Design.php

PRESSURE DOSING SEPTIC SYSTEMS https://inspectapedia.com/septic/Pressure_Dosing_Septic_Design.php

DOSING CONTROL for SEPTIC MEDIA SYSTEMS https://inspectapedia.com/septic/Septic_Media_System_Dosing_Control.php

ALTERNATING BED SEPTIC SYSTEMS https://inspectapedia.com/septic/Alternating_Bed_Septic.php

On 2020-02-25 by Carol

What size dosing tank do I need with a 1500 gallon septic tank?

On 2019-11-16 - by (mod) -

Brenda

You want an onsite septic engineer to test the soil, examine the site plan and survey, figure out where you could install a septic, what capacity is needed, etc. WIthout that work, in my opinion any cost estimates are wild arm-waving.

On 2019-11-16 by Brenda D

I am looking to open an family entertainment center for kids in an undeveloped area. How do I determine the cost associated with installing a septic center?

On 2019-10-07 - by (mod) -

Terry

Weight limits for traffic or vehicles moving over septic tanks and septic drainfields

Thanks for an excellent question of how much weight a septic system can withstand - and one that stumps me. I don't think there can be a reasonable single "right answer" to how much weight can a drainfield withstand before there is damage because the variables are missing:

- what are the soil properties: density, current moisture level, gravel content above, around, and below the piping?

- what is the depth of the piping and how were trenches constructed?

- how much traffic is moving over the field?

- how is the traffic weight distributed? Tires vs wide tread equipment vs equipment driving over heavy plywood sheets?

- where on the field does the traffic flow: over all of it, over an edge, parallel to drainfield trenches or across them

Examples:

a 10 ton dump truck driving across the head (where pipes enter) of a rectangular drainfield comprised of soft soil during wet weather with pipes 12" below the surface using older orangeburg or clay or thin PVC piping is likely to crush pipes and collapse trenches

Driving over or making a parking area over a conventional fiberglass or steel or even most residential concrete septic tanks risks collapsing the tank unless the tank is specifically constructed and designed to withstand vehicle traffic.

a conventional walk-behind power-driven residential grade lawnmower weighing just a hundred pounds or so used for mowing the surface is not likely to damage the fields

recurrent driving over a drainfield by automobiles or farm tractors risks compressing the soil and interfering with transpiration and absorption of effluent even if pipes are not broken.

I've done stupid or mean things in my life of which I am deeply ashamed. But I'm not fool enough to claim that anyone can give you a simple "right answer".

I can give a qualitative answer:

ANY kind of traffic over a septic drainfield or soakaway or leach field that is heavy enough to compress the soil is damaging the field and reducing its life; still-heavier weights may actually crush septic piping causing immediate failure.

ANY kind of vehicles driving over a septic tank heavier than a golf cart or residential lawnmower risk collapsing or damaging the septic tank unless it is rated and designed to withstand such traffic.

Also see SEPTIC TANK DESIGN STRENGTH SPECS https://inspectapedia.com/septic/Septic_Cesspool_Design_Strengths.php

Also see DRIVING or PARKING OVER SEPTIC https://inspectapedia.com/septic/Dont_Drive_On_Septics.php

On 2019-10-07 by Terry

What is the maximum weight piping can withstand before a field is compromised? And once compromised how long do property owners have to rectify the situation?

On 2018-11-05 by (mod) - terms like "hotel" or "house" are not enough to know how big to make a septic tank or system

Eric

The required size of a septic system is not specified based just on "hotel" or "house" but rather on the anticipated daily volume of wastewater that it needs to handle.

So there is no intelligent answer like "sure, 100,000. liters"

Instead we need an actual estimate of the total daily wastewter flow. See the tables given

at COMMERCIAL SEPTIC DESIGN - home

Also take a look at the typical water usage information

at WATER USAGE REQUIREMENTS

On 2018-11-05 by Eric Agyemang

Please can I know the size of hotel septic thanks

On 2018-10-14 by (mod) -

Joe

The EPA as well as your local state or municipal septic regulations are definitely not intended to "minimize" a septic system nor to minimize the use that you can make of a site.

Rather, those regulations are intended to tell us the *maximum* use that can be made of a site without creating unsafe or unsanitary conditions such as, in essence, peeing into the well or contaminating nearby lakes, ponds, streams or waterways.

If we exceed or violate those rules we're doing just those things: adding space to a campground is wonderful - I'm a camper myself and enjoy more space and less crowding. But I'd not return to a campground that was sending open sewage into the stream where I swam or into the water I drank or into the fish I eat.

A separate issue is the zoning one. A local ordinance that restricts one acre lots to one home does not address campground use where a far greater number of people may be on the site at one time than would ever possibly work with a conventional home septic system.

it makes no difference if that occupancy is intermittent: the septic system has to be able to handle the peak occupancy: It’s not as if it’s ok to poop in the well just sometimes but not always.

Before giving up on your expansion you want to get help from a septic design engineer who is familiar with local regulations, who knows local code officials, and who can help you with a design that works for the site, including the available space, soil properties, distances to streams etc., and thus that can meet code.

For example once resolving the zoning issue and thus the site usage issue, f there isn’t room for a conventional septic drainfield and tank system to handle your occupancy, there may be alternative septic designs such as a small on-site wastwater treatment facilitiy that can handle the wastewater.

Certainly for a 100 to 200 occupancy site, that’s likely to be what’s needed, as no conventional residential septic tank and drainfield would ever suffice.

On 2018-10-14 by joetuz

we are planning on second phase of a growing campground. We are planning on installing 100 new campsite for RV and campers.

Most campers are 2 person ownership since this is over 55 age, 6 month seasonal facility.

Currently local ordinance restricts one acre lots to one home. There is nothing on the books for CAMPGROUNDS/RV. but your EPA water stats clearly reflect difference in single family homes.

Our goal is to max our facility not min. its potential safely.

On 2018-08-25 by (mod) - septic TANK size depends on the total daily wastewater volume not just the number of occupants

Terry the septic TANK size depends on the total daily wastewater volume not just the number of occupants (though that's a key factor as you'll see in the table on this page).

Some septic tank sizes are at SEPTIC TANK SIZE https://inspectapedia.com/septic/Septic_Tank_Size_Tables.php

BUT that too is very incomplete: the critical factor for you is less tank size and more what is going to happen to the wastewater effluent that leaves the septic tank ( a tank is normally always full so 100 gallons in = 100 gallons of effluent out into the drainfield)

Rather it's then the drainfield size that will be critical for you - you need space to fit a field that can handle the daily wastewater flow OR if you don't have enough space for a conventional soakaway bed your local building or health department may accept a proposal for a small onsite wastewater treatment plant that discharges acceptably clean water to the environment.

To answer that question you need an onsite septic engineer who examines the space at your site, the setback requirements for tank and field, and who does soil tests to get the soil percolation rate - a slow perc soil needs more areas of soakaway

On 2018-08-23 by Terry

I'm opening an Adult Day Care with a possible capacity of 20 - 25 clients daily, our hours of operation would be 8 hrs daily 5 days a week. I wanted to know what size septic tank would be necessary if sewer connection not available.

On 2018-04-04 by (mod) - calculate the estimated daily wastewater flow

If you assume each patron uses a toilet or urinal at least once during a visit you can calculate the estimated daily wastewater flow. Both tank and drainfield need to accommodate that.

I might select coffee shop or dining hall from the table at COMMERCIAL SEPTIC DESIGN

On 2018-04-04 by Zgraywine dog

I am trying to estimate septic tank capacity for a small winery with a tasting room. At peak (once or twice a week) we may have 75 patrons.

There are 3 stools and 1 urinal as well as a few sinks. The soils perks VERY well. Thoughts?

On 2018-03-17 by (mod) - Your system needs to handle perhaps 2000 + gallons of wastewater or more

Blake,

Your system needs to handle perhaps 2000 + gallons of wastewater or more; you may need a very large septic tank and commercial onsite wastewater treatment system.

I'd start with a local septic engineer who can examine your site and who knows the country, city, state or provincial septic regulations where you live.

On 2018-03-17 by (mod) -

Glenn and Plumbing engineer


Thank you plumbingengineer for helping out with Glenn's question about a septic system for handling a peak-load

Here are some details that clarify the problem and explain why a typical septic tank and drainfield designed with capacity to handle a building that normally just has say 4-10 occupants cannot handle a surge of 200 people without risk of failure.

The problem here is not simply the septic tank size, it's the discharge of a large volume of wastewater into the absorption field over a short time period - during the event.

If we assume, generously, that during an event attended by 200 guests and say 20 staff, or 220 people total, we're looking at a total waste volume of no less than 2,200 gallons of water flowing into the septic tank during the event for toilets and hand-washing alone, with no other water usage such as for cleanup or cooking.

IF we had a 2200 gallon septic tank

and

IF the septic tank were pumped absolutely empty before the event

THEN yes the tank could absorb that wastewater surge without flooding the drainfield

You would have to pump the septic tank out completely before every event. And I'm doubtful that local health authorities will approve such a system.

That is not the normal situation.

Normally a septic tank is completely full, all the time.

In the normal case, then, during the event, 2,200 gallons of wastewater (or more if there is kitchen waste, cleaning wastewater, etc) is pushed into the absorption field.

There is no conventional residential-type septic drainfield or absorption field design that handles that volume of wastewater during a short burst of activity. The system will be flooded and will fail.

On 2018-03-17 by theplumbingengineer

@Glenn,
The tank needs to be sized to handle the peak load. The leach field can be sized for average flow. In other words, you have an event where 200 people use the facility for several hours so the wastewater needs to be contained in the tank. Then you have about a week before the next event for the leach field to absorb it. You should hire an engineer to do the calculations based on occupancy, use, drainage field absorption rate, and local code requirements.

On 2018-02-18 by (mod) -

School estimates of septic wastewater loads are in a table on the article COMMERCIAL SEPTIC DESIGN. You messy find that a wastewater treatment plant iswhast will fit your needs.

On 2018-02-17 by Kimberly

I am director of elementary school with 50 students and 10 adults. School in session 5 days/wk, 9 months/yr. Looking to move to a property with septic system. How big system do I need for my school? Property currently used as three bed house with out buildings.
Thank you!

On 2018-02-08 by (mod) -

The challenge, Glenn, is that your system has to be able to handle the peak usage loads - 200 people over a day or two.

For that you may need a mini onsite wastewater treatment system rather than a conventional septic tank and soakaway bed.

On 2018-02-08 by Glenn

We are building a 200 person barn to use for weddings and other events with around 6 toilets in total.

There will be a kitchen area with sinks and a dishwasher. Mostly used on the weekends. What type of system would this require?

On 2018-01-23 by Anonymous

If we have a store with 3 tolets, percolation test. Of 31,42,45 minutes the how big woold the arborbtion area need to be?

On 2018-01-17 by (mod) -

Riya

A conventional septic tank and absorption field will not handle 6,000 occupants. You will need an onsite wastewater treatment facility.

On 2018-01-17 by riya

size of septic tank for an university with around 6k students

On 2017-08-23 9 by Anonymous

Barn

On 2017-08-23 by Anonymous

What would I need for a turkey bar 1000 gallons aday

On 2017-06-19 by Jlee3rd

I want to set up a small RV park (less than 20 units)
What type of septic system do I need?

On 2017-06-01 by (mod) -

Anon,

The answer to your question is not going to be the number of septic tanks alone, but how the Wastewater will be finally processed and disposed of. You would need such a large physical area for any conventional septic system for the number of people that you describe that it does not seem reasonable to me.

More likely you would need a local on-site septic Waste Water Treatment Plant.

On 2017-06-01 by Anonymous

for labor camp with 626 people how many septic tank required

On 2017-05-31 by Bill Sandefur

How much does it generally cost for a commercial size septic tank for a business such as Flash Foods /Gas stations?

On 2017-01-25 by Terry

@Kelly Scott,
Did you ever figure out how much you needed for the wedding event center? Did you get any costs estimates? I am thinking of building one of these too.

On 2016-10-06 by Kelly Scott

Trying to figure how big a septic tank I will need for a 150 person wedding event center for weekend only

On 2016-07-21 by (mod) -

Count people, not RVs.

On 2016-07-21 by Anonymous

I'm trying to figure out how big a tank I will need to support 9 rv,s

On 2016-07-15 by (mod) -

Blake, our table at COMMERCIAL SEPTIC DESIGN gives typical wastewater flow for various occupancies including a bar.

You can multiply the Bar flow rates given for employees and customers by your numbers to get a reasonable guess at the total wastewater flow.

Example: using your 200 people number, that's 200 to 1000 gallons of wastewater per day - before adding water use for employees.

Your septic engineer will give you a design spec for that volume of wastewater.

Yes it's possible, but not cheap. You may need more than a conventional tank and drainfield, perhaps a small wastewater treatment plant.

On 2016-07-14 by Blake

We are trying to figure out what a septic field would look like if it were to support a bar with an occupancy ranging from 150-200 people.

Is there a way to figure out some general information about a septic field of this magnitude? Is it even possible?

On 2016-07-13 by (mod) -

Donna that's a question to take to your local septic engineer and building department. You'll have to review the intended property use, required septic size, septic system type, space needed for that septic system type, local property line setback regulations, and of course what else will be located on the property.

Other considerations include soil properties and presence of nearby waterways. In sum, no competent honest answer can be offered that will be right for all property circumstances, but even knowing nothing about your specific property, it sounds rather doubtful.

On 2016-07-12 by Donna Lass

Am looking at property at lake granbury, has no septic system, is about 2,400 Sq ft property, is it large enough if you can put a system in.

On 2016-06-22 by (mod) - what the septic system designer will consider in setting septic tank and field size

I would hire a local septic design engineer. She will consider all of the design factors involved - more than I can know from just your question's text - for example in even for occasional use the system has to be sized and designed to handle the maximum number of simultaneous occupants; that doesn't mean that the disposal field has to be "oversized" as a dosing system and large septic tank might be considered part of the design for intermittent use.

But the designer will consider

- the soil properties: percolation rate

- terrain properties: slope, size of area available, laoyout, piping distances

- ground water and high water table

- presence of nearby waterways and water supply well that require clearance distances from septic components

- tank location and size

- local regulations

Question: how often should I clean the restaurant external grease trap & aerobic septic system?

I have a year old aerobic commercial system servicing two restaurants the service contract expiring,

1. A 2,000 external grease trap for a 2,000 sf Mexican food medium volume, two commodes, with grease pots external from the system to dump most of the grease and oils.

2. A 3,000 external grease trap servicing a 4,225 Italian food low volume, two commodes little grease and oils.

When this restaurant was in a different location with 4 other businesses on a 3,000 tank it was pumped every six months.

I have three quotes all within $ 200.00 of each other and all say their scheduling is the best.

Either tank has been pumped since startup or according to all 3 pumpers are not at manitory levels yet. Quote 1 pump every six months, quote 2 pump every 6-8 months, and the other 8-12 months.

I know you can not issue a concrete decision without additional information but a best guesstimation would be helpful. Thank you in advance. The company with the best price and the every six month time frame does not have the best reputation. What would suggest? - J.R. 7/21/12

Reply:

A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem, evaluate the condition of the system, and thus give more specific advice - which I realize you understand from your question. That said,

Because expert sources have made clear the number one cause of failiure in Aerobic systems was inadequate maintenance, and because the cost of system failure remedy can be high, it makes sense to me to err on the "safe" side.

You could use the commecial wastewater flow estimates in the article just above to see what the standard design parameters should have been for your system.

The true economics of managing onsite wastewater treatment systems have to include not only the periodic cleaning costs, but an allowance for repair or replacement of system components. And that latter figure has to be increased to allow for risks of costly damage if we wait too long between cleaning intervals.

But more immediately, I would have each system opened and pumped & cleaned immediately.

But as part of that cleaning process, ask the service company to make measurements of the actual levels of sludge, scum, grease, in each system.

By comparing the measurements to the allowable or desired net free area in the treatment tank, or to our own recommended sludge and scum levels found

at MEASURE SEPTIC TANK SCUM & SLUDGE you can calibrate your actual system usage and accretion of waste products that need cleaning against the time since last cleanout.

With that data you can then schedule cleaning more accurately and economically.

Let me know what you find when the systems are actually measured - what we learn will surely help other restaurant operators.

Questions in search of a septic design engineer:

(May 6, 2015) kunal suryawanshi said:
what size should be for four storeys 1bhk apartments

(June 20, 2015) Lori said:
We're looking for a septic system that will take a 50 gal dump at once and not overflow the solids to the outlet side. Is there a special tank or way it should be installed?

(July 21, 2015) Penny said:
I own a 4 commercial washer laundromat. Also connected to the same septic is two washrooms and a small pizzeria open 4 days a week. The septic is located in a rural area. My septic area is wet, and smells of sewage. I was told that the soap doesn't break down and clogs the runs. What kind of system should I put in?
Thank you for your time, Penny
pcrowe@eagle.ca

Reply:

Lori,

Ask your septic designer about the design for a large holding tank and a dosing system that spreads the dumping of wastewater over time.

Penny

The determination of what kind, size, capacity, layout and location of septic system replacement you need, you'll need an on-site septic engineer or designer. That's because in addition to the daily wastewater volume and type that your laundromat produces, the engineer has to look at the soil properties at your site (for example the percolation rate), the space available, and the terrain shape. Those will determine the type, size, and layout you need.

I speculate that your business produces a very large volume of soapy graywater that requires a very large wastewater absorption area (drainfield, leachfield, soakaway bed, drainage trenches seepage pits). I would ask the septic engineer about graywater treatment options that might permit recycling and re-use of at least a portion of this water, both for environmental reasons (water usage reduction, reducing contamination of the envrionment) and economical reasons (reduced water usage, possibly construction of a smaller onsite wastewater treatment facility).

Let us know what your engineer recommends and we can discuss this further.

Question: event center septic tank and drainfield design

(Feb 13, 2016) Campbell said:
I'm curious about how big of a system I would need to operate and event center for 250 people each day.

Reply:

You cannot install a conventional septic tank and drainfield to support 250 people. You'll need an onsite waste treatment facility.

Question: septic for a martial arts school

(Apr 10, 2016) Chris said:
Will a 1000 gallon tank support 4 bathrooms, no showers, at a martial arts school?

Reply:

Chris:

1000 gallons gives us 250 toilet flushes with old toilets, or 666 flushes at 1.6 gpf modern toilets. I'd cut those numbers in half to allow for washing hands.

250 toilet flushes ought to handle a lot of martial artists.

But then you haven't said how often the tank is going to get refilled, nor how.

Without knowing how many people are actually using the system daily, or better, how many of them use the toilets daily, I can't give a more definite answer.

Question: septic tank size for a food store

(Apr 27, 2016) Anonymous said:
How big must a sewer tank be for a store that serves food ,.but no dine-in

We have 3 employees, private bathroom, not for public... can we do that

Reply:

Treat it as based on the number of employees in a food preparation facility - see the tables above.

Question: commercial building with one toilet and bath

(June 5, 2016) Anonymous said:
What size of septic tank should I use in a commercial building that has a 1 toilet and bath?

Reply:

I think your design engineer will say the answer depends on what the water usage is in the building - what "commercial activity" is going on, not just on number of employees.

Question: septic for a Nashville TN recording studio that hosts clients

Anonymous said:
We are planning to accommodate out of town clients for our recording studio on 4 acres. We also may use for personal events such as family or out of town guests when spaces are not used. Our goal is to use this as a mini RV hookup for about 8 spots.

If affordable have 1 or 2 cabins such as koa in the far future. Regardless trying to plan with the future in mind, dont want to redo later as we grow. How do we determine the size and type of septic do we need for this? No city sewers are here.
Davidson county nashville tn

Reply:

I would hire a local septic design engineer. She will consider all of the design factors involved - more than I can know from just your question's text - for example in even for occasional use the system has to be sized and designed to handle the maximum number of simultaneous occupants; that doesn't mean that the disposal field has to be "oversized" as a dosing system and large septic tank might be considered part of the design for intermittent use.

But the designer will consider

- the soil properties: percolation rate

- terrain properties: slope, size of area available, laoyout, piping distances

- ground water and high water table

- presence of nearby waterways and water supply well that require clearance distances from septic components

- tank location and size

- local regulations

...

Continue reading at COMMERCIAL SEPTIC DESIGN - topic home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• COMMERCIAL SEPTIC DESIGN - topic home
• DISINFECTION SYSTEMS, SEPTIC EFFLUENT
• SEPTIC SYSTEM DESIGN SPECIFICATIONS for ALTERNATIVE SYSTEMS
• SEPTIC DRAINFIELD SIZE
• SEPTIC TANK SIZE
• WATER QUANTITY USAGE TABLES

Suggested citation for this web page

COMMERCIAL SEPTIC DESIGN FAQs 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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