Septic Tank Baffle FAQs

Septic tank baffle requirements
Septic tank baffle replacement
Septic tank baffle replace with tee: seal at tank wall
Septic tank baffle venting
Septic tank Tee FAQs
Use elbows at septic tank tees or baffles?

Septic Tank Baffle Requirements FAQs

Do all concrete Septic tanks have baffles?

Do all concrete Septic tanks have baffles. I don’t think mine has a wall in it On 2018-07-09 by Bobby

by (mod) - all septic tanks need inlet and outlet baffles or tees

They all require a baffle or a tee - otherwise,

on the inlet end of the septic tank, floating scum and solids in the septic tank will block the inlet and cause sewage backup in the building

on the outlet end of the septic tank floating scum and solids in the septic tank will flow out of the tank and clog the drainfield and drainfield piping, leading to costly repair

Can't we just remove the septic tank baffle and do nothing more?

Is it safe to remove the inlet baffle to our septic tank and not replace it? On 2017-02-18 by Ron

by (mod) - No, it is not safe to omit the inlet baffle to a septic tank

No, Ron, that's a bad idea and risks sewage clogs at the septic tank inlet. The result could be a nasty backup into the building.

Septic Tank Baffle Repair / Replacement FAQs

Can septic tank baffles be replaced?

Can septic baffles be replaced? - Ted

Moderator reply:

Sure, Ted.

In the Septic Tank Care article links given at the end of SEPTIC TANK BAFFLES see

• SEPTIC TANK BAFFLES - used on concrete or steel septic tanks
• SEPTIC TANK TEES - made of PVC pipe, used on all types of septic tanks

Is it normal to repalce a broken concrete septic tank baffle with a plastic Tee?

Question:I just had the outlet baffle repaired by a licensed septic service.

The concrete baffle nearly gone although you cannot see the outlet pipe.

To create a baffle they installed a 3" size pipe tee and slid the horizontal pipe into the existing 4" outlet and the used shims to hold it in place. Is this a correct method of repairing a baffle? On 2016-06-27 by Mike S

Answer by (mod) - yes; here are the details

With the exception that of course there can be a problem that you don't describe and I cannot see by e - text, the repair sounds normal and typical to me, except that in my OPINION that 3-inch diameter tee is too small and more-easily clogged.

Better to install a 4-inch tee - or a tee that matches the outlet pipe diameter as shown in our sketch above, adapted and expanded from one by the Alaska DEC.

by Mike S

Thanks Dan. I just thought since there is a space between the different size pipe that scum would leak into the field.

by (mod) - yes provided the tee is sized properly

Mike,

ndeed we do not want leaks at the new baffle-tee.

Worse than effluent leaking out if the tank might be groundwater leaking in,flooding and damaging the system. Worst casees of backflow I see also cause sewage backup into the building.

It's easy to buy or fabricat an internal coupling that will connect a 4-inch tee to the 4-inch outlet pipe, losing only a very small amount of internal diameter. That's better than downsizing to a 3-inch line.

I suspect your installer didn't know that such a coupling is easy to buy or make.

by Mike S

Sorry, I did not mean that effluent was leaking outside of the tank and system.

My concern is the space that is created with the insertion or sliding a smaller baffle pipe into the larger outlet pipe. That gap is allowing some surface water to escape directly to the outlet pipe rather than all the effluent flowing through the tee into the outlet. I really appreciate your help and value your opinion.

Answer by (mod) -

We're still waving arms and trying to understand the situation.

Look. IF the tee at a septic tank inlet or outlet is not completely sealed against outside water intrusion, effluent can leak OUT of the tank, and surface water from the outside of the tank can leak INTO the tank. Either of those is a bad idea.

by Mike S

I understand your last reply. What happens when you place a smaller pipe inside a larger pipe and then have fluid flow through the pipe by gravity?

The fluid will flow in and around the outside of the smaller pipe and eventually all fluid will meet in the larger pipe and travel where it is supposed to go.

That is the situation I have. The fluid that is flowing around the outside of the smaller pipe is the scum layer inside the septic tank flowing out to the leach field.

I would guess that 90% of the right fluid or effluent is flowing correctly through the smaller pipe and 10% of the scum layer is leaving the tank and going out to the field. How bad is that 10% leaking through to the leach field?

The septic people tell me it's not that big a problem because the solids will not pass. I hope this makes sense. I thank you for the time you taken on this issue.

Explanation by moderator: how septic tank tees do their job

Mike the septic tank tee must extend down into the septic tank enough to get well below the floating scum layer - that's what prevents solids from flowing out into the drainfield.

Details are at SEPTIC TANK TEES

Other notes:

I'm not worried about clarified effluent flowing around a tee and into the drianfield as that's what's supposed to be moving in that direction from the septic tank.

But if there are leaks on the septic tank interior that bypass the inserted tee and allow grease or other floating scum layer components into the drainfield that's not good - that's exactly what the tee is supposed to be preventing.

If the repair of a septic tank baffle is made by inserting a Tee into the tank outlet pipe from the tank interior side, and if the inserted tee fits snugly into the outlet line so that there aren't any gaps, some installers may not bother to seal that connection;

if the inserted tee is letting scum layer grease or floating solids sneak around the tee/baffle and into the tank exit line that's something to avoid by sealing the tee on the tank inside during the installation.

by Mike s

You confirm my thinking. There will have to be more work done to make it right. Thank you very much Dan. This is a terrific web site!!

I was charged a very high cost to install a septic tank baffle tee

I was charged$1,058.06 to install a rear and a front baffle tee on my septic tank. That seems very high to me for Parts that cost around $50.00. I would appreciate your thoughts and thanks for your time. (July 14, 2014) Mike Brantley

Reply:

Mike

It might have been gouging, or it might have been quite fair. The parts are often the least costly part of a job.

Other costs such as excavation and restoration work or pumpout if that was part of the job would of course increased the job cost.

How can I add inlet and outlet baffles to my old septic tank?

My septic system is over 30 years there are no baffles on the inlet and outlet as welll they appear to be made from clay - it is not pvc for sure, how can i install baffles ? On 2018-01-14 by Mike Ruyak

Reply by (mod) -

Mike

Adding baffles can stop pushing solids into the drainfield - though after 30 years I am not optimistic about remaining drainfield life in any case.

Except for minor repairs that might be made to a concrete or steel septic tank baffle when the tank has been emptied and cleaned, we usually fix the probley you describe (no baffles at all) by installing a PVC Tee in the septic tank at the tank inlet and outlet openings.

Typically a septic contractor or a plumber will install a plastic Tee at the inlet and outlet of the septic tank, just as you'll see in the article SEPTIC TANK TEES.

The tee outside diameter OD has to just fit inside of the incoming or exiting sewer piping, OR a new Tee is installed through the openings in the ends of the septic tank and connected to the existing piping outside of the tank.

Watch out: clay sewer piping lines may be old and fragile and, depending on just what sort of piping was used, leaky, tipping, sagging - if that were my system I'd have a sewer cam inspection of the entire lines in and out of the tank so that we don't get into a problem of repeated repairs or overly-optimistic guesses about the remaining life of the system.

Do I need to empty the septic tank to replace a broken outlet tee or baffle?

My question is whether there is any reason to empty the tank before repairing the outlet baffle. In my case it's removal of a rusted metal baffle and replacement with a PVC T.

For Brahms: I was told yesterday to use concrete to seal any gap between the PVC and original outlet pipe. On 2011-08-20 by JMichel

by (mod) - Often, no, but see our serious safety warnings!

JM, no, provided you have safe access you don't need to empty the septic tank before replacing the baffle; but pumping the tank makes it possible to inspect the rest of the tank for damage; the fact that you're removing a METAL septic tank baffle is a red flag - you probably have a steel septic tank.

If so you might find, on pumping the tank, that the tank sides or bottom are also rusted through. If you need a new tank you won't want to have wasted time working on baffles for the old one.

Watch out: don't work on the septic tank alone, nor lean over it, without training and protection against sewer gases. You may faint and fall into the septic tank - a quick and nasty death.

Watch out: for getting cut on rusty sewage-contaminated metal when removing old steel tank baffle parts.

Brahms:

I agree with JMichael - you can seal a plastic tee with concrete; a problem with using some other sealants is that they may not bond to dirty or wet surfaces. A mechanical seal is fine if nothing is going to fall out later.

What is the cost to replace a septic tank baffle?

what is the average cost of replacing supply outlet baffle ? On 2018-08-09 by Douglas

by (mod) - average cost of replacing supply outlet baffle ?

$50. or less for parts, $400. for labor if backhoe excavation is not needed.

If a backhoe and excavation are needed the cost can be much more, depending on site factors like ease of access and septic tank depth.

Why does a deteriorating septic tank baffle have to be replaced?

Why does a deteriorating baffle have to be replaced if it still works (May 21, 2015) vicki

Reply:

Vicki

I'm not sure I understand the question, nor that I disagree with "if it still works" provided that "works" is accurate.

"Works" in my view means that a component is sufficiently reliable that we can forget about it without having to face undue risk of a catastrophe - such as a clogged sewer line and backup into the building.

So a concrete septic tank baffle with a couple of chips out of it is fine. But a septic tank baffle that is cracked, falling off, or that shows signs of having been over-flowed means that diagnosis and repair are needed, and a baffle that has been lost needs to be replaced promptly.

How I added a Septic Tank Tee on the Inlet End

I just noticed my septic tank had an inlet pipe with no Tee on it. I have enlarged the inlet hole on the side of the tank since the original hole had a 22 degree slope.

I then Installed a Tee. Even with the hole enlarged I still have about 1/4 of the 4"pipe constantly filled with water (before it gets to the tee and of course at the tee). Is this OK or does the sewage level have to be below the inlet pipe?

The only other option for me would be to reduce to a 3" pipe once the inlet pipe gets to the septic tank. This is because my 4"pipe is already riding the bottom of the septic tank lid. Just FYI, this is my normal water level as everything checks out OK on my outlet tee and drainfield.

Thanks so much in advance and for this AWEsome site! On 2016-09-27 by Jon

How do we secure a new septic tank baffle in place?

We have to replace an outlet baffle on our septic tank. The pipe in inside is flush with the septic tank. How do we secure the new baffle? On 2016-09-12 by Abby

Answer by (mod) - how to connect a plastic sewer line to an existing pipe using a DIY internal coupling

You may be able to purchase a plastic pipe tee whose male insert is smaller in diameter such that it fits inside of the existing outlet pipe. Look for an internal coupling.

You can also make an internal coupling that fits inside the diameter of the remaining septic pipe in the opening by starting with a short 10-12-inch long section of ABS or PVC pipe of the same diameter.

1. Use a power saw to cut out 3/4" to 1" of the pipe from one end to the other - a simple straight saw cut.
2. Then use a clamp to squeeze the repair pipe to a sufficiently small diameter that you can slip it half-way into the existing sewer pipe line.
3. Leave about 4" sticking out, then insert that protruding end into your new septic tank tee.

Otherwise, as a distant second best solution, you will need to remove part of the existing pipe to make room in the septic tank wall to insert and seal the tee.

Should I pump the septic tank before replacing a broken baffle?

Septic baffle article very helpful.

Baffles broken on my septic system. Need to replace. Also need to pump out septic system. Hasn't been done in 12 years.

Should I pump system first and then fix baffles or the opposite fix baffles then pump.

Also one of the leach fields has surface flooding.

Many thanks.

Moderator replies: yes but see this safety warning

Yes pumping the tank makes it easier to install a replacement septic tank baffle or tee, though sometimes, depending on the exact situation, one can insert a new tee without pumping first - if sewage level isn't above the outlet opening and if the new tee will just slip into place.

Watch out: leaning over or falling into a septic tank can quickly be fatal. Never work alone, and get expert help for this job.

Can I replace a septic tank baffle myself? Do I need one if my effluent is disposed of by sprinklers?

We had a septic company come and check our 2 compartment aerobic septic system. We knew the airator was out so I had 1 ordered already. The guy was going to pump it but said the grey water pump was in the bottom and full of mud/dirt. He said the tank was cracked due to a tree root probably.

We freaked out! Thats a really expensive hunch. So we had him move the pump out of the mud/dirt just a little higher and reset it.

The other day it rained and we heard water running into the tank and the ground had decayed in, towards the Earth,like a sink hole. We dug it up. Turns out the dirt was flowing into the outlet baffle, and probably has been for quite some time.

My question is can I buy an outlet baffle an install myself? How hard is it? I was told I could cap it because I have field line sprinklers? On 2016-08-18 by April

Advice by (mod) - multiple warnings about the septic system you describe

The articles

• SEPTIC TANK BAFFLES
• SEPTIC TANK TEES

describe typical repairs for septic tank outlet baffles; a plastic tee is installed; a common plumbing part.

But

Watch out: leaning over a septic tank can quickly be fatal as you can be overcome by methane gas. And falling into a septic tank is usually fatal too.

Never work alone, and get expert help for this job.

Watch out: No, a septic system using effluent sprinklers does NOT mean that septic tank baffles aren't needed. Without baffles, solid sewage will quickly clog any effluent dispersal system.

Watch out: when you hear water running back into the septic tank and no water is being run in the house that tells me that your septic effluent dispersal system is flooded, broken, and needs repair or replacement OR there is surface or subsurface running into and flooding your whole septic system - which will ruin it.

Septic Tank Tee Seal into Concrete Septic Tank Wall FAQs

What materials will connect the leach PVC to the concrete septic tank?

I am installing a new leach line. What materials will connect the leach PVC to the concrete septic tank? Does the PVC just set in the hole or is there a connector of some sort? On 2015-11-02 by Marty Costello

Answer by (mod) -

Marty:

You want to seal the connections at the tank with any of the above

- a factory, friction-insert rubber gasket

- polyurethane caulk

- concrete/cement mix

You want a good seal not just to keep sewage from leaking out of the tank but also to keep groundwater from leaking into the tank. Examples of such leaks are at
SEPTIC TANK LEAKS https://inspectapedia.com/septic/Septic_Tank_Leak_Causes.php

So don't just leave the PVC piping at the septic tank "loose" in a hole in the tank ends.

Make Opening into Concrete Septic Tank Wall to Install Pipe or Tee FAQs

How do we remove the knock-out to run a pipe out of a concrete septic tank?

Hi. We are wanting to open another inlet hole. I have located the pre-cast hole at the side needed. What is the best way to remove the cement from said hole... Drilling or Chisel ? On 2016-06-07 by Kathy

Reply by (mod) -

Concrete tank, right? Goggles, gloves, mallet-small sledge, small masonry chisel - will do the job. Drilling makes a lot of breathable silica dust that's better left in bigger pieces and on the ground.

by Kathy

Yes concrete.. Thank you Dan.

How do I make an opening to add an outlet baffle and pipe at an old septic tank?

I have and older septic tank that needs an outlet baffle. But there is no opening at that end where it has to be installed. So what do I have to do to install it. On 2015-11-11 by Stan

Reply by (mod) -

Every septic tank has an inlet opening for the incoming waste line and an outlet opening for the outgoing effluent line to the D-box and drainfield or soakbed. If there were no tank openings it'd not be a septic tank it'd be a holding tank and you'd be pumping it very frequently and at great expense.

There are two approaches to keeping solids from flowing out of the tank and clogging the system: a rectangular concrete or half-round steel baffle built into the original concrete or steel septic tank or if those are not present a plastic TEE such as those described in the article above.

Just above our discussion see my recommended continued reading links and you'll see the details.

Continue reading at SEPTIC TANK BAFFLES on how to detect a lost or damaged septic tank baffle or a damaged tank tee; when & how to add a septic tank tee or select a topic from the More Reading links shown below.

Or see SEPTIC TANK TEES - for details about replacements for lost or damaged septic tank baffles

Is it OK to chip a hole in the concrete tank to connect piping?

Does chipping away at the concrete of the tank to put in the piping cause the tank to be more at risk for cracking in the future?

This article was super interesting, so I'm just looking for a bit more information. You've got a great blog going here. (May 23, 2014) Sophia Liam

Reply:

Sophia, septic tanks are normally cast with an opening for pipe connections or a knock-out that is partly-cut-trough the tank wall and is removed by a simple and careful step with a hammer (and eye protection).

Chipping at the tank shouldn't increase the crack risk, but indeed any discontinuity in a concrete casting (e.g. windows in a foundation) can create a variation in stress that can be the locus of a future crack.

Is it ok to move a septic tank inlet

I have a septic from the 1980s and have built a new house going from a mobile home.

With a square septic Is there only one inlet and outlet front and back or is there also one on the side it can be switched too. Currently inlet is north and outlet is south. Can the inlet be moved to the west.? (July 17, 2014) Keith

Reply: yes, but watch the inlet level vs outlet level

Keith,

Most likley, yes, but you'll need to look into the septic tank to be sure that there is (or you'll need to add) an inlet baffle at the new inlet connection

and you'll need to be sure that the inlet opening is at the proper height (above the outlet level).

Watch out: going from a mobile home to a new house, the size and capacity of the septic tank and drainfield may be inadequate.

Septic Tank Piping Elbows Instead of Tees FAQs

I found a simple Elbow rather than Tee at septic tank inlet

I've been reading this website off and on for two years as I've had ongoing struggles with my system.

Recently I discovered my line was busted between my house and the tank. In digging it up and clearing it out, I also discovered that my inlet appears to be cast iron into a concrete tank. The inlet appears to be more of an elbow instead of a T.

Also, the inlet seems to have corroded and severely narrowed the opening into the tank, likely causing the backups that lead to the pipe failure. Is there a way to "bore out" the cast iron inlet that is corroded, or do I need to look at replacing my inlet (and likely outlet) pipes?

Can an expert knock out the old cast iron inlet and replace it with a new plastic one without damaging the tank? (June 7, 2014) Patrick said:

Reply: replace the elbow with a tank tee

Patrick,

I would excavate the tank inlet end, break out the corroded cast iron, and if there is no intact tank baffle inside the septic tank I'd cement a new plastic tank tee in place, sealing the tank opening around the tee with hydraulic cement or if the surfaces are clean and dry, a suitable flexible sealant.

IF the tank baffle is intact you can go straight into the tank in the baffle area with a new plastic line connection, just stop the projection in the tank flush with the tank wall.

Can I use an elbow instead of a tee at the septic tank

I currently have a single 500 gallon round concrete tank with just one lid. The top of the tank sits 5 feet below grade. As far as I know the baffles are good on either end. If they were to be damaged is there anything that could be done with just an elbow instead of a tee and still work? Could i use a tee and drill the top of the tank and run a pipe to the surface? (June 16, 2014) brian said:

Reply: - bad idea

Brian I'm unclear on why you want to use an elbow instead of a Tee - which would make inspection and cleaning rather difficult and might increase the clog risk.

If you are thinking of inserting a Tee as an outlet or inlet baffle and wanted to extend that to the surface I'd prefer to install a septic tank riser of larger diameter, making inspection and cleaning much easier, but yes one could just extend a tee to the ground surface. Be sure to seal against leaks into the septic tank.

In our article SEPTIC TANK TEES you'll see more about why installing elbows instead of tank tees is not a good solution for septic tanks. You may need to click to show and read those faqs.

I've seen 90's used instead of Tees, but a Tee gives you the ability to see and clear clogs while the 90, pointing down, does not.

The tee also will allow sewage to overflow at the tee top and enter the septic tank if the tee outlet becomes clogged. A clogged 90 degree elbow outlet will give you a sewage backup in the building.

I'd stick with a Tee.

Watch out: I suspect you're describing an old steel concrete septic tank that is way too small by any contemporary standard. The risk is a septic field failure if the tank is not pumped frequently and that risk is greater if the original steel tank baffles have rusted away.

Details are at SEPTIC TANKS, STEEL 

A banging noise echoes from the elbow tube of my septiic tank

I have a new home and there is s banging noise that echoes from the elbow tube of my septiic tank. I don’t hear anyone else’s? What do I do? On 2018-09-19 by Norah

by (mod) - Track down and fix banging noises in septic or sewer piping

Norah:

Here are several articles explaining the causes and cures for the banging noise you describe.

• BANGING BOOMING NOISE DIAGNOSIS & CURE - home
• BANGING WATER PIPES

Septic Tank Baffle Top Venting FAQs

Do septic tank baffles need a vent hole?

Do the baffles need to be vented and a 1" hole +/- be provided? (May 28, 2015) Bill said:

Reply:

Bill:

Because the normal waste level in a septic tank is always below the upper edge of any type of septic tank tee or baffle, they do not need additional venting.

If you see sewage flooding over the baffle top then the tank is flooded, its outlet is blocked, or the drainfield or soakbed has failed.