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Septic Tank Pumping Table - When to Clean the Septic Tank

Septic tank cleaning or pumpout frequency guidelines or rules:

This article provides a septic tank pumping schedule based on septic tank size and level of usage. This document explains a key point in how septic systems work: the septic tank & septic system cleaning schedule - when to pump out the septic tank.

We describe all of the reasonable methods for determining the recommended frequency for cleaning out a septic tank: using a cleanout frequency table, using objective measurements, using an electronic tank monitor. We also explain what is septic tank effluent retention time, why to measure septic tank scum and sludge levels in sum we provide a comprehensive guide to answering: How often should septic tanks be pumped?

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

How Often Do You Pump Out A Septic Tank?

Septi tank cleanout started (C) Daniel FriedmanThe septic tank cleanout schedule table given just below lists the recommended septic tank pumping frequency according to septic tank capacity and household size.

The septic tank pumping schedules given here were calculated based on basic septic system design concepts requiring a septic tank to provide a minimum of 24 hours of wastewater retention assuming 50 percent digestion of the retained solids.

Common septic tank pumping frequency mistakes

  1. Failure to pump the septic tank frequently enough: leading to an early drainfield failure and costly repairs
  2. Pumping or cleaning the septic tank too frequently, wasting money (though you're wasting a lot less money than the cost of a new drainfield.

    Some septic pumping contractors and some other "experts" give a fixed rule of thumb that serves their own interest, such as "pump your septic tank every year" or "pump your septic tank every two years" or in a case we know about in Minnesota, "pump the septic tank every couple of months or after you've had a lot of visitors".

    It would be smarter to pump the septic tank before or both before and after heavy use if we know the septic system is marginal. Pump the tank before a period of heavy usage to avoid a sewage backup during the heavy usage interval and afterwards to get back to normal usage levels.

    See SEPTIC BACKUP PREVENTION for tips to avoid a septic problem during times of anticipated heavy septic system usage.

    Contractors may give this advice without first having actually considered any information about the septic system capacity, level of usage, age, or other conditions. It's a great example of "OPM" or "other people's money" - spending someone else's money to reduce your risk that they'll complain that your advice wasn't safe enough.

  3. Pumping the septic tank with the fantasy that doing so will "fix" a clogged or failed drainfield. All you really gain is a few days of toilet flushing before the tank has re-filled.

See this complete list

SEPTIC TANK PUMPING MISTAKES
and fantasies about how septic tanks work and how they should be maintained.

Actually inspecting the septic system, diagnosing any problems or failures, and inspecting conditions inside the septic tank will tell us whether the tank is being pumped at the correct frequency.

The removal of septic waste by cleaning the septic tank is a critical step in septic system care as it extends the life of the septic field. Even if you don't care how septic systems work you need to know when to clean the septic tank by pumping out septic waste.

Using the septic tank cleaning frequency table just below, simply look up your tank size and number of building occupants to see how often the septic tank should be cleaned. Later in this article we list other factors that can increase or decrease the recommended pumping rate.

Table I. Septic Tank Pumping Frequency in Years

Septic Tank Size

Gallons / Liters

Household size - Number of Occupants
1 2 3 4 5 6 7 8 9 10

Septic Tank Pumping Frequency in Years

500 gallons * / 1890 liters 5.8 2.6 1.5 1.0 0.7 0.4 0.3 0.2 0.1 --
750 * / 2840 9.1 4.2 2.6 1.8 1.3 1.0 0.7 0.6 0.4 0.3
900 / 3400 11.0 5.2 3.3 2.3 1.7 1.3 1.0 0.8 0.7 0.5
1000 / 3800 12.4 5.9 3.7 2.6 2.0 1.5 1.2 1.0 0.8 0.7
1250 / 5000 15.6 7.5 4.8 3.4 2.6 2.0 1.7 1.4 1.2 1.0
1500 / 5500 18.9 9.1 5.9 4.2 3.3 2.6 2.1 1.8 1.5 1.3
1750 / 6500 22.1 10.7 6.9 5.0 3.9 3.1 2.6 2.2 1.9 1.6
2000 / 7500 25.4 12.4 8.0 5.9 4.5 3.7 3.1 2.6 2.2 2.0
2250 / 8500 28.6 14.0 9.1 6.7 5.2 4.2 3.5 3.0 2.6 2.3
2500 / 9500 30.9 15.6 10.2 7.5 5.9 4.8 4.0 3.5 3.0 2.6

NOTES to the Septic Tank Pumping Schedule Table:

Portions of this information were provided by the Penn State College of Agriculture - Cooperative Extension.

We have edited and added to the original septic tank pumping guideline material based on research and field experience testing, inspecting, and installing septic systems and based on study of other reference sources on septic system maintenance and design.

Septic Tank Pumping Schedule for Part-Time Occupied Buildings

Question: What Schedule should I use to Pump a Part-Time-Occupied Summer Home?

22 Sept 2015 Bill said:

I have a camp with a 1250 gal. tank. It is seasonal, only used in the summer. We have shower, toilet and sink that empties in the septic. What schedule should I use to pump?

Reply: Divide the Septic Pumping Table Frequency by the Portion of Year of Building Occupancy

Bill you can take any point in the septic pumping schedule table and then increase the length of the interval between septic tank pumpouts by making this reasonable-guess:

1. Choose the number of building occupants to find the proper line in the pumping shcedule. Also choose the table entry for the size of your septic tank in gallons.

2. Choose the number of months during a year that the building is occupied

3. Calculate the new pumping schedule by dividing the number in the table on this page by the fraction of the year that the building is occupied.

Example:

Household size = 4 people
Septic Tank size = 1250 gallons
Table pumping frequency: every 3.4 years (Keep in mind it would be ridiculous to think that we can know precisely the conditions in an individual septic tank - these are general guidelines)

3.4 x 12 = 40 months between tank pumpings

Months your Camp is occupied = 4

Months in a year = 12

Portion of the year your camp is occupied = 6/12 = .5 or 50%

Pumpout Schedule from Table / Portion of Year Occupied = 40 months / .5 = 80 months between pumpouts.

Watch out: before launching into an extended we-don't-have-to-pump-the-septic-tank-because-InspectApedia-said-so interval, it would be smart to have your septic tank pumped and its condition inspected so that you are starting from a known condition.

Whenever you open and clean a septic tank the following can give a more accurate idea of the actual septic tank pumping frequency needed at a specific building:

Watch out: for any building that sees occasional surges of heavy septic tank use, simply pumping the tank based on average occupancy over the year can get you into trouble.

The big surge of sewage and wastewater can overwhelm the septic system's ability to cope, particularly you may flood the drainfield or push solids into the soakbed, drainfield, or seepage bed.

You might head off trouble by pumping the septic tank out completely just before the surge of visitors. A sewage backup into the building or out onto the ground during a wedding can be a nasty touch to an othewise lovely event.

See SEPTIC TANK PUMPING REASONSwhere we describe pumping the septic tank before a par;ty.

Also see SEPTIC TANK PUMPING MISTAKES

Pumping Schedule for Sewage Holding Tanks

Onsite sewage disposal system holding tanks, where there is no septic field, will need to be pumped more frequently based simply on the rate and volume of septic waste inflow.

A smart design for sewage or septic holding tanks is the inclusion of a septic tank alarm system that will tell when the tank needs to be pumped. Set the alarm float to sound the alarm early enough that you can continue to use the plumbing system while waiting for your septic pumping contractor to arrive.

See SEPTIC PUMP ALARM SYSTEMS

A periodic inspection of the septic holding tank levels is an alternative but not one that most people actually manage to follow with enough care to avoid trouble.

Electronic Monitors for Septic Tank Scum & Sludge Levels Give Septic Tank Cleanout Frequency

Septic tank monitor

Below at References we also describe an electronic SEPTIC TANK MONITOR [image] or grease trap monitor from Worldstone.

These devices can track sludge, scum, or GREASE LEVELS [image] in order to best schedule septic tank pumping or grease trap cleaning. This product is suitable for commercial installations and possibly for some residential septic tank systems.

According to the company,

"Data from monitors can help establish appropriate service intervals, and document maintenance for regulatory compliance. Alarm features can help detect abnormal conditions and prevent costly backups."The company also produces an oil tank level monitor.

Thanks to reader Robert Shirley for this tip.

OPINION - DF: this product is a great idea for commercial installations or problem septic installations. Substituting actual septic tank scum layer thickness or scum level thickness data for the septic tank pumping schedule table above may allow the tank to be opened and pumped less often - saving some money.

Watch out:  But don't forget that regular opening and inspection of the septic tank, such as happens when the septic tank is to be pumped out or "cleaned", gives an additional opportunity to check for other septic system problems that could be leading to a costly failure, but that don't directly concern the septic tank sludge or scum layer thickness.

Examples include the discovery of lost or damaged septic tank baffles, septic tanks leaks that allow ground water to flood the septic system, or septic tank leaks out of the tank.

Alternative Septic Tank Pumping Frequency Guidelines: the University of Minnesota Septic Tank Inspection Frequency Point System

The University of Minnesota has published "Septic Tank Pumping Frequency Guidelines" that take a different approach than the cookbook table of septic tank sizes and number of building occupants shown in our table above.

But the document does not really tell the homeowner when to pump the septic tank. Instead it calls for essentially very frequent septic tank "inspections" to decide if pumping is needed, without, regrettably, explaining what that inspection would entail nor how that inspection would decide that the septic tank needs to be cleaned.

Watch out: In sum, we cannot recommend this chart's use as the best or sole option for deciding when to pump out a septic tank, nor does the chart actually answer that question, as we explain below.

However it would indeed be a "safe" approach to inspect the septic tank conditions at every one, two, or three years, which is the actual end result of this misnamed worksheet.

Septic Tank Pumping Frequency vs Septic Inspection Frequency - clarified

Instead of taking the widely-used septic tank size and number of bedrooms table approach, U.Minn. experts have provided a table or questionnaire that when answered, gives a septic tank inspection frequency in years.

The appeal of this approach is that it allows a homeowner to take into consideration factors that would either increase or decrease the interval for septic tank inspection based on factors that increase or decrease the septic failure risks posed by the home and its usage.

Unfortunately factors enumerated in the point-counting approach have some troubles of their own, as we explain below.

The added cost of annual to tri annual septic tank inspections might be weighed against the safety, fine-tuning, and "actual septic tank data" approach to septic tank inspection frequency we describe below, or the simple and easy to use septic tank pumping frequency table we provided above.

Watch out: the septic tank worksheet does list some interesting septic tank risk factors, as we elaborate below. However, overall the worksheet we reviewed underweights the septic tank failure risk of some factors and overweights or confuses others, and it does not directly address the risk of drainfield damage caused by flushing high volumes of wastewater (laundry, water softener) through the septic tank.

But the chart doesn't do that anyway. Although the chart's title is "Septic Tank Pumping Frequency Guidelines" it does not provide that information. Instead, if you complete all of the work and analysis in this chart, you end up at one of three frequencies at which you should inspect the septic tank condition to determine if it needs to be cleaned:

Septic System Failure Risk Level Factors vs Recommended Inspection & Pumping Frequency
Septic Worksheet Risk "score"  
0-8 = Low Risk

2-3 year septic tank inspections:

Evaluate the septic tank conditions every 2-3 years to see if cleaning is needed.

In Minnesota some municipalities require septic pumping or inspection every 3 years.

Requirements vary in other U.S. States & Canadian Provinces as well as of course municipalities in other countries.

8 - 18 = Medium Risk

1.5 - 2.5 year septic tank inspections:

Evaluate the septic tank conditions every 1 1/2 - 2 1/2 years to see if cleaning is needed

19-26 = High Risk Annual septic tank inspections: Evaluate the septic tank every year to see if cleaning is needed

Notes to the table above

Adapted from the U. Minnesota septic tank pumping frequency worksheet cited below at reference [5]

Do We Need to Evaluate the Septic Tank ?

Really? What the heck does "Evaluate the Septic Tank" mean? This question is not addressed in the UM worksheet. Without septic tank inspection points, pass/fail criteria, or trouble signs for which the "evaluator" is to be alert, we just don't know what to make of this advice and we certainly can't expect any consistency in the results.

However we answer this question in excruciating detail beginning

at SEPTIC TANK INSPECTION PROCEDURE where we list many things that should be evaluated to avoid septic system failures or worse, unsafe conditions; or you can "cut to the chase" as mom says, and have your septic contractor open the septic tank

and MEASURE SEPTIC TANK SCUM & SLUDGE, to know objectively if the tank needs pumping.

Watch out:  "Evaluation of septic tank condition" is not well defined. Experts generally agree that there are a number of inspection points including the septic tank sludge and scum layer thickness that determine that septic tank pumping is needed (or not) but that there are other inspection points that are very important such as evidence of backup, damaged baffles, tank flooding or septic tank leaks, and of course septic tank safety: safe covers, no signs of collapse risk, etc.

Some Factors that Should Increase the Septic Tank Pumping Frequency

If you don't know where the septic tank is located,

see SEPTIC TANK, HOW TO FIND.

At TANK INSPECTION PROCEDURE we describe how to inspect the septic tank before, during, and after tank cleaning operations.

 




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Reader Comments, Questions & Answers About The Article Above

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

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2021-05-03 by (mod)

@Bill, thank you so much for your generous comment. I worked hard on this material for many years so I'm particularly grateful when readers find it useful. And I particularly welcome healthy debate that helps us understand these topics better.

On 2021-05-03 by Bill


Thanks for discussing. BTW, I really appreciate the website, the info I find here and the recognition that rules of thumb aren't always suitable. I expect to come back and look at several of the topics. Best, Bill

On 2021-05-03 by (mod)

@Bill,

As I'm trying not to pretend I know more than I do, Bill, forgive me for not being more-specific.

Sure, in concept, cascaded septic tanks help with separation out of solids - we see that design already in the use of single tanks with multiple compartments. Each successive compartment collects sludge and scum, at a reduce rate from the compartments ahead of it;

When the septic tanks need to be cleaned it's the first compartment that always gets the most-frequent attention.

So in simple concept a series of septic tanks - that is, piped in series rather than in parallel, gives improved solids separation and settlement/separation of scum and sludge.

But to move beyond that simple and reasonable concept to quantitative specifics like volumes, settlement rates, cleanout frequencies, etc. seems to me very speculative; the physical shape, baffle design, and wastewater movement patterns in the tanks is surely important and surely depends on tank and baffle design specifics.

On 2021-05-03 by Bill


Thanks. You will note that the tank capacity I described would be 3500 gallons, a bit more than 3200. I wanted to focus on the narrow question that I posed - is the multiple chambers strategy I described a good idea ?
I am well aware of the drainfield needs.

There are over 1200 feet of buried perforated 4" diameter pipe on gravel beds.

The soils were perc tested plus allowance made for more loading than I described.

My question is about the best strategy for the septic tanks, their arrangement, and number of chambers to keep suspended solids from leaving the tanks with the effluent. Any comments on that will be greatly appreciated.

On 2021-05-03 by (mod)

@Bill, thanks, those are thoughtful and interesting ideas about septic tank sizing for episodic large wastewater loads.

At SEPTIC TANK SIZE https://inspectapedia.com/septic/Septic_Tank_Size_Tables.php you'll see a "Table of Required Septic Tank Size Based on Daily Waste-Water Volume in Gallons"

and noting that to avoid a septic failure your system has to be designed to handle peak wastewater inflow loads, you'd want 3200 gallons of tank capacity.

Less than that risks pushing solids into the drainfield;

Septic tank cascades, settlement chambers, septic outlet filters, all help with that concern.

But remember that your effluent disposal system - the drainfield - too, has to be able to accept that peak flow, OR you'd need to build a still much-larger septic tank tank capacity combined with a dosing system that accepted the inlet into holding tanks and then spread out the drainfield dose over a longer period.

You'll need an onsite septic engineer who can specify what should work for your site, to include information about your site size, space, loading rate and soil percolation rate.

On 2021-05-03 by Bill

Septic tank(s) for a retreat center with irregular occupancy. Some people live on site continuously, but when a retreat comes for one to three weeks, the numbers may increase to around 15 - 30 people. Old concrete septic tank has deterioriated, plan to replace with new plastic ribbed design tank(s).

Considering to put 2 or 3 tanks in series as a way to trap suspended solids.

Have years of data that show daily flow ranging 500 - 2000 GPD irregularly depending on occupancy. Considering to put 2000 gal. tank first, followed by a 2-compartment 1500 gal tank with the idea that most scum and sludge will be caught by the 2000 gal, then remnant caught by first compartment of the 1500 gal, then virtually all that remains caught by second compartment of the 1500 gal.

Not sure if this idea is correct because agitation in each compartment will be as the ratio of flow-through to the net free volume in the compartment, but it should still be better than just one compartment, especially as scum / sludge build up in the first compartment and reduce the net free volume there. Comments ?

On 2021-02-19 by jim

https://inspectapedia.com/

On 2021-01-08 by (mod)

Anon

Apologies: nobody can answer your question "how long does a septic tank get full" - which I take to mean "how long does it take for a septic tank to fill up?" . It's like asking how long does it take to fill a box of unknown size and of unknown inflow rate.

How big is the box?

But I can offer this explanation that may help you: in normal use a septic tank is always "full". Septic tanks are the initial recipient of sewage from your building(s). Wastewater flowing into the tank pushes a like volume of sewage effluent (liquid without solids) out of the tank and onwards to the effluent disposal system: a drainfield or leachfield or treatment plant.

Please see details at

SEWAGE FLOW & DESIGN FLOW ESTIMATES https://inspectapedia.com/septic/NYS75-A.3_Sewage_Design_Flow_Estimates.php

and

SEPTIC TANK SIZE for septic tank sizing guidelines & codes -- https://inspectapedia.com/septic/Septic_Tank_Size_Tables.php

On 2021-01-08 by Anonymous

How long does a septic tank get full if there's 8 households using it?

On 2020-12-18 by (mod)

Barry

See SEWAGE TREATMENT PLANTS, RESIDENTIAL https://inspectapedia.com/septic/Packaged-Cluster-Septic-Systems.php

A complete list is at SEPTIC SYSTEM DESIGN ALTERNATIVES - home https://inspectapedia.com/septic/Septic_System_Design_Alternatives.php


On 2020-12-18 by Barry

I am looking into an alternative system to process septic waste from a new home to be built in an area that will not be able to use the conventional septic leach fields. I am wondering if anyone knows of a method that is close to the conventional way of disposal of waster water?

I see we could install a second tank for the waste water and wanted to hear from anyone who has such a setup how ofter do you'all have to have your waster water tank pumped out?

Please include your tank size and how many folks are living in your home so I can have something to compare to my situation as its only going to be 2 people living in the home we are going to have built.

Thank you for your time and advice, Barry

On 2020-10-14 by (mod) - eptic tank pumping schedule when there are multiple septic tanks at a property.

John

Thanks for a helpful question on figuring the septic tank pumping schedule when there are multiple septic tanks at a property.

As my much-admired inspector friend Mark Cramer (Tampa) says .... it depends.

How are the 2 septic tanks connected?

If each is receiving sewage from the building the each needs to be pumped as a 900 gal. tank.

If the two are connected in series and sewage flows just into the first tank while effluent flows out of the first tank and into the second one - a common design also referring to the second septic tank as a settling chamber,

then the first tank is pumped as a 900g tank - on that schedule, but the second tank will need cleaning less-frequently;

In that design you'd have the septic cleaning contractor inspect the level of sludge and scum in the second tank to determine when it's due for cleaning.

On 2020-10-14 by John

I have 2 tanks, each are 900 gallons - so1800 total gallons. Do I say my tanks are 1800 gallons or do I follow the 900 gallon guideline? Former owners did full dual-tank pump every 6 years and a one tank pump in between the full tank pumps every 3 years. So full pump, 3 years, one tank pump, 3 years, full pump, etc. I can't tell if that's the right method or not?

On 2020-07-03 by (mod)

Anon

Septic tank pumping frequency depends on tank size and incoming wastewater volume

Please see the details and pumping frequency table given in the article above and let me know if you have any questions

And to be clear: it's not that the septic tank needs to be "emptied" - a septic tank, in active use, is normally always "full" all the time.

What is needed is periodic septic tank "cleaning" which means removing the settled sludge and floating scum.

If we don't do that the free area in the tank gets too small and as a result suspended solids are pushed out into the absorption field (drainfield) thus ruining it and leading to expensive repairs.

On 2020-07-03 by Anonymous

How often does a home septic tank need to be emptied?

On 2020-07-02 by (mod)

Thomas

Septic holding tanks are used in some limited situations where it's not possible to install a working septic treatment system. However they are illegal and no longer permitted in most locations and jurisdictions. That's because it's not a system but simply a holding tank.

To use the phrase septic system we need to include not simply a holding tank but also a method of treatment so that the liquid effluent waste water can be safely discharged into the environment.

Holding tanks are also used of course in campers and RVs.

Just for completeness you might be thinking about package unit septic systems that are considered a miniature Waste Water Treatment Plant All In one. Those systems may use a treatment method that does not involve a soil or drain field approach

On 2020-07-02 by Thomas

Is there a septic system with no drain fields or aerators just a holding tank that requites pumping out periodically?

On 2020-07-02 by Tom

A septic system with no drain fields or aerators but has a holding tank that requires pumping periodically.

On 2020-05-27 Zoe Campos said:

Thank you for reminding me that refusal to clean my septic tank can lead to serious damages and costly repair in the future. My parents don't actually remember the last time they cleaned it but smelling foul odor near the lines might be an indicator that they haven't. IT might be a good idea to hire experts in septic services and see if it's not too late for septic tank cleaning services.

On 2020-05-08 by (mod)

What on earth are they going to do each month. Ask for specifics.

And what kind of septic system do you have installed? Some require periodic maintenance, though monthly?

On 2020-05-08 by Danny

Septic company wants to schedule monthly maint schedule after it pumped tanks why monthly?

On 2020-01-06 by (mod)


jack said:

I love that you mentioned that you could save money on potential repairs if you are to get your tank pumped often enough. My wife and I have been talking about finding ways to properly keep our tank in good condition, and it will be important for us to know that we could find the right ways to. I will be sure to get it pumped often, so we could save on repairs.

On 2019-08-27 - by (mod) -

Sue your daughter would not have and could not have called us for septic care.

InspectAPedia.com provides building and environmental diagnostic and repair information.

In order to absolutely assure our readers that we write and report without bias we do not sell any products nor do we have any business or financial relationships that could create such conflicts of interest.

InspectAPedia is an independent publisher of building, environmental, and forensic inspection, diagnosis, and repair information for the public - we have no business nor financial connection with any manufacturer or service provider discussed at our website. We very much welcome critique, questions, or content suggestions for our web articles.

However if specific questions arise about the condition of your daughter's septic system we welcome those questions and may be able to offer suggestions or to pose questions to ask your LOCAL septic pumping company.

On 2019-08-26 by Sue Buckner

Has my daughter called for septic care.. Jean Sue Buckner? I know the septic needs pumping on 12238 Circle Dr. .. I owe this property and responsible for the upkeep..I want to know if this is being done.. She is very sick and needs help.. thank you 🙏

On 2018-11-15 by (mod)

Dr kirsch

WATER SOFTENER CLEANING & SANITIZING

Describes the proper procedure for sanitizing a Water Conditioner or water softener. The required amount of bleach is not arbitrary nor is there a single correct number.

Rather the bleach dose when sanitizing a softener depends on the resin tank size.

Also if you don't put the bleach in correctly you can have a devil of a time getting rid of the smell.

The article explains how to do that. Please take a look and let me know what you think.

On 2018-11-14 by drkirsch@yahoo.com

have septic sys. with 1000 gal. holding tank. water softener that generates about 4 to 5 days. water has live bacteria. we run about 1/4 cup chlorine thru softener, and 1/2 cup to 200 gal water heater. am i running to much disinfectant to my sys.?

On 2013-03-27 - by (mod) -

Greasetrap:

We post your comment below without the link that you had included - spam filter prevents comments containing links

Fascinating device that measures Grease Trap and septic levels in the article above. I am an IT Guy and am always looking for a technological solution. However, my experience with Grease Traps is that the schedule to which they are pumped is typically mandated by the municipality.

Ergo, even if you knew your grease trap or Grease Interceptor were at 80 Percent capacity. When its time to get it pumped, as proscribed by your local health inspectors....you will still need to have your Grease Trap or Septic System Pumped

On 2012-08-05 - by (mod) -

Paul, a reasonable answer would be to look in the table of septic tank pumping frequencies above and notice that for a 1000g septic tank and a property occupied by two people we'd pump the tank every 5.9 years or about every 6 years.

If you occupy a home just half time (6 montns / 12 months = 1/2) then just figure you want to pump half as often

half as often as 6 years would be 12 years.

I think to be safe I'd pump the tank now to start from a known condition.

Then I'd probably try pumping it again at 8-10 years at which time I'd check the sludge and scum thicknesses - and if they were minimal, pumping could be on that 12 year interval.

WATCH OUT: however - it makes sense, even if not pumping out the tank, to inspect it more often, perhaps every year or three - check for damaged covers, unsafe covers, lost baffles or tees, or signs that the tank is flooding or leaking. Because if you lose a tank baffle and never notice it for more than a decade you are also ruining the drainfield.

On 2012-08-05 by Paul Philbrook

How often should a 1000 gal septic tank be cleaned if the home is occupied six months of the year by two persons ?

On 2012-06-12 by randy

Buying a house that has been sitting empty for a year and a half.
Was told no need to pump out the septic but it seems to me it should be done.
Have no idea if it has ever
even been pumped. Your input would be great.

On 2012-05-25 - by (mod) -

Thanks to Anon about "backwards septic tanks" - indeed the inlet and outlet tank baffles may be of different heights - the outlet baffle or tee extends deeper into the septic tank to help assure that it is clarified effluent, not floating solids and grease, that are pushed out into the drainfield. IN some septic tanks cast concrete baffles may indeed be of different heights at inlet and outlet.

At many septic tanks, however, that outlet tee height is set when the tees are inserted in place in the inlet and outlet ends of the tank during tank installation. In sum, the inlet and outlet baffles or tees are at different heights in septic tanks but the height difference may not be a fixed part of the tank itself - it depends on tank design and materials.

Thanks again to "Anonymous" for pointing out this important feature. What it means is that if your septic tank baffles or tees are "reveresed" with respect to inlet and outlet, you risk both clogging at the septic tank inlet end, and at the outlet end you risk allowing floating solids and grease out into the drainfield - shortening its life.

On 2012-05-25 - by (mod) -

Harry, adding yeast is NOT RECOMMENDED and can actually damage your system by causing agitation and forcing solids out of the tank into the drainfield. No septic tank additives are necessary for a properly working system, some are harmful, and in many jurisdictions are as a result, illegal.

We agree that a food grinder or garbage disposer unit adds solid load to a private septic tank; you can keep the unit, but would most likely want to increase the tank pumping frequency accordingly. As you just had the tank pumped after 5 years of use, if you ask the septic pumper for details about the thickness of scum and sludge layers s/he found, that will give you a clue about whether or not you need to pump the tank more or less frequently.

On 2012-05-25 by Harry

Our current home is our first experience with septic. I just had tank pumped (750 gal) after about 5 years (2 people). The guy that pumped it said to add yeast occasionally. After reading your data even our "experts" are wrong. Glad we found your site. Next project may be taking garbage disposal out.

On 2012-03-06 0 9 by Paul

Orangeburg pipe was mainly used during WW2 because of the war effort. It is basically layers of tarpaper compressed together to make sections of pipe. Most of the metal at the time was being used. If indeed you do have this type of pipe, you should replace it, because if it has not already done so, it will eventually flatten.

On 2011-05-20 - by (mod) -

Yes I have heard of a backwards septic tank. To me that means that the septic tank INLET is LOWER than the septic tank OUTLET - that tank can not work properly and risks sewabe backup into the building.

But some septic tanks are indeed designed with a series of internal chambers intended to separate solids from the effluent before it is discharged to the drainfield. Depending on septic tank design, a final settling chamber may be smaller than the main waste-holding chamber.

So if the tank were installed "backwards" with wastewater flowing first into the smaller settling chamber, that would be a problem and the septic tank would not function properly.

On 2011-05-16 by m.s

Have u ever heard of a tank bein put in backwords



...

Continue reading  at WHEN to CLEAN THE SEPTIC TANK or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see SEPTIC TANK PUMPING SCHEDULE FAQs questions and answers posted originally on this page

Or see these

Recommended Articles

Suggested citation for this web page

SEPTIC TANK PUMPING SCHEDULE at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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