Questions and answers about using pipe tees as septic tank inlet or outlet baffles or tees to prevent inlet our outlet sewer line clogging.

This article series explains the requirements for septic tank inlet tees and septic tank outlet tees and explains why the length of the tee extensions is important to prevent septic tank or septic piping clogging and to protect the life of a drainfield.

Septic Tank Tee Questions & Answers

Here are answers to questions posted originally at SEPTIC TANK TEES - please be sure to check out the types of tees and baffles, problems, and solutions discussed there.

On 2020-01-15 by (mod) - proper baffle tee lengths?

Rob

Probably you're fine, but I confess I don't have the full picture of your septic tank's design.

The right concept is that the bottom of the PVC tank tee extends deep enough that you're not sending floating scum out into the drainfield,

and the top of the PVC tank tee extends several inches above the highest liquid + floating scum level in the tank so that crud doesn't flow over the top and out into the drainfield.

And the bottom of the outlet tee is 2-3 inches lower than the bottom of the inlet tee

Details and example dimensions are in the article above in the section titled

Sample Specifications for a Septic Tank Inlet Tee

On 2020-01-15 by Rob

I had to repair the outlet baffle of my septic tank with pvc. I matched the length of the old concrete baffle which was about 36 inches is this ok?

On 2019-10-02 by Anonymous

Dose the tank need some type of ventilation device

On 2019-09-06 by (mod) -

Yes, Johnny, it's called a septic tank tee - see SEPTIC TANK TEES https://inspectapedia.com/septic/Septic_Tank_Tees.php

However the Tee in the septic tank is not likely to be the cause or cure for septic or sewer gas odors indoors. Possible but not likely. There may be a blockage or a venting problem. Knowing when the issue began and what else was going on just before that may be diagnostic.

Watch out: never lean over or even work around a septic tank alone - falling in is quickly fatal and you can be overcome by methane gas. Ask for help from a septic expert.

On 2019-09-06 by Johnny Hall

Is there a down spout within the septic tank, reason, I believe its come off. Smells coming into home

On 2019-07-27 by (mod) -

Jim

Watch out: I would NOT try to treat a whole septic tank with root killer. You may kill off the septic tank bacteria and create a worse problem.

You will need to either remove the trees or plants whose roots are invading the septic tank or to dig and install a barrier to keep them out.

Watch out also: if tree roots are invading a septic tank or any septic line that usually means that there has been a sewage effluent leak there or nearby.

At a septic tank I'd look for a septic tank cover or access port or riser or pipe connection at the inlet or outlet end that is not sealed.
The same leakage out of a septic tank can mean surface runoff leaks IN to the tank and septic system, flooding it and causing a failure.

The Tee rather than elbow permits inspection, cleaning, and also helps avoid a blockage in the tank inlet and outlet. I'd use a tee not an elbow. The open top of the tee is what gives you access while an elbow won't. (Your elbow was going to face down and extend the proper distance, right?)

I'm not sure what sort of blow bomb you're considering - some photos and more details would be helpful.

But I'm doubtful that any pressure method will successfully clear roots from a sewer line; more likely you'll just push the debris downline and make for more trouble later.

Typically a sewer drain cleaning company will use a power augur or "roto rooter" type device to clear the line. IN the hands of an experienced operator she can often also feel the condition of the pipes as the augur passes through the line, and can detect a broken or collapsed line - important information. That plus distance would tell you what other digging and line repairs are needed.

On 2019-07-2 by Jim

My inlet baffle area is completely filled with roots embedded in a tar like substance. I have cut the roots where they entered the tank and am treating the tank with chemicals to kill the roots. There is no access cover to this area so all my work is taking place through the inlet hole

. I have managed to clear enough room that I think I can get a elbow with extension Dow into the effluent in place. Is there a reason a Tee is used instead of a elbow?

I like the idea of a elbow if I have to clean the inlet in the future. If I use a “blow bomb the elbow should clear no problem and the same with a cable machine. I would know that I was cleared all the way to the effluent this way. Is using a elbow a bad idea?

On 2019-07-12 by (mod) -

Fred

I can see why you're asking a question about septic tank baffle or tee repair - I cannot make an iota of sense from what you've been told. How can there be a "concrete inlet baffle" on a "fiberglass septic tank" ?

While I agree that a lost outlet tee or baffle quickly leads to trouble ( a failed drainfield), both inlet baffle or tee and outlet baffle or tee are necessary - if they were not they'd not be in tank design specs. The inlet prevents clogging of the inlet pipe with floating sewage and scum as those rise in the septic tank. Such a blockage can result in a sewage spill inside the building - itself a costly mess.

On 2019-07-11 by fred

We're buying a house with a bad concrete inlet baffle. Septic tech report said he can't replace, as he'd have to drill into the fiberfglass tank. Does this sound legit? Report also said that the inlet isn't as important as the outlet baffle. Does that sound legit?

THANKS!

On 2019-02-25 by (mod) -

Most septic tanks have a single Inlet Port. If you need to connect multiple waste lines from the house, normally they joined the pipe in to the septic tank ahead of that entry port.

On 2019-02-25 by Tn

Can you have multiple intake pipes are the house?

On 2019-02-25 by (mod) - multiple pipes from house to septic tank

Most septic tanks have a single Inlet Port. If you need to connect multiple waste lines from the house, normally they joined the pipe in to the septic tank ahead of that entry port.

On 2019-02-25 by Tn

Can you have multiple intake pipes are the house?

On 2019-02-24 by (mod) - grinding up scum and sludge in the septic tank

I'm not sure what you mean by gas grinder for septic tanks, but if you're referring to using a machine to break up sludge and scum in order to more thoroughly pump the solids out of the tank that maybe what's happening.

On 2019-02-24 by Jimmie

Why would you use a gas grinder in a septic tank before pumping.

On 2019-02-06 by (mod) -

Mike

Can you add an image (button below) so I can see what we're patching?

I've used Epoxy to patch a hole in rigid PVC piping and I've used clamp-around clamps + rubber to instdall a removable patch.

The tee is typically sealed into the tank using a flexible sealant (caulk) such as silicone or polyurethane caulk and is a devil to R&R

Older plumbers used asphaltic cement - like roof flashing cement.

Yeah some tanks come with rubber or plastic septic-tank-pipe seals like the one from PolyLock (http://www.polylok.com ) that I show below - click to enlarge and see more specifications.

On 2019-02-06 by mike

I have a 2006 1000 gallon concrete septic tank. On the outlet tee I have a small 1/4' x 1' hole next to the concrete tank at the top of the pvc pipe. Is there a patch kit that will last a life time? If so does it come in two pieces that will wrap around the pvc pipe. after its time for the next clean out, I would replace the tee, how does the new tee seal in the concrete tank? Does the concrete tank come with rubber seals installed in the concrete?

On 2019-01-15 by Epicureaninc

@Zane Lindstrom,
Depends when installed, codes are always updating

On 2018-12-18 by (mod) -

Matt

I expect by now you've discovered if you had a septic contractor look at your tank that the proposal you suggest Men at Work. That's because the inlet to the septic tank needs to be higher than the outlet.

On 2018-12-14 by matt

i have had some backups in the line connecting my house to the septic tank. We ran a camera down the pipe and it looked like a lot of standing water.

I have dug out the pipe now and noticed that it is actually 2 inches higher at the tank than it is at the house.

It is about a 14 foot run so im guessing i should have about 2 inches grade as well. im hoping what we can do cut the line and cap it at the tank and then run a new line about 5 inches deeper and drill a new hole into the tank

. I have a huge tank right now so im not worried about losing a bit of volume.

can this be done or will lowing my inlet about 5 inches affect other parts of the septic system? thanks!

On 2018-12-03 by (mod) - The septic tank tee will be near the top of the inlet end and outlet end of the septic tank.

Dennis,

The septic tank tee will be near the top of the inlet end and outlet end of the septic tank.

See

SEPTIC TANK DEPTH

SEPTIC TANK DESIGN DEPTH

You can find those articles in the ARTICLE INDEX on this page - just above this comments box section.

On 2018-12-02 02:18:42.700295 by Dennis

Inspection pipe on septic is pic. Pipe s stick g out of ground one and a half foot. Dud down one foot and have not found break yet. How much farther should I have to dig.

Hit septic inspection pipe with lawnmower. Broke pipe. Need to replace, how deep is pipe buried nto ground

On 2018-11-30 - by (mod) -

If the piping is intact that is without damage or leaks, then it's fine. There's no code requirement to use a specific material I'd rather there is a range of materials that are permitted. Are you sure it's concrete? If you could send me a photo that would be helpful. You can attach a photo using the add image button.

On 2018-11-30 by Zane Lindstrom

My daughters tank inlet line is concrete. Is that typical. It's just falling apart. I'm no septic guy but I thought it should be PVC or cast iron. Thanks

On 2018-11-30 by (mod) - how deep do I have to dig to find the septic tank tee?

Dennis,

The septic tank tee will be near the top of the inlet end and outlet end of the septic tank.

See

• SEPTIC TANK DEPTH
• SEPTIC TANK DESIGN DEPTH

On 2018-12-02 by Dennis

Inspection pipe on septic is pic. Pipe s stick g out of ground one and a half foot. Dug down one foot and have not found break yet. How much farther should I have to dig.

Hit septic inspection pipe with lawnmower. Broke pipe. Need to replace, how deep is pipe buried nto ground

On 2018-11-30 by (mod) -

If the piping is intact that is without damage or leaks, then it's fine.

There's no code requirement to use a specific material I'd rather there is a range of materials that are permitted. Are you sure it's concrete?

If you could send me a photo that would be helpful. You can attach a photo using the add image button.

On 2018-11-30 by Zane Lindstrom

My daughters tank inlet line is concrete. Is that typical. It's just falling apart. I'm no septic guy but I thought it should be PVC or cast iron. Thanks

On 2018-11-11 by (mod) -

No Dianne not necessarily; a field can fail and become clogged without necessarily showing water at the surface.

That's quite common in some locations, depending on soil depth and soil type. E.g. in northern MN a drainfield may be 8 feet below ground in clay soil. It can clog and begin go dispose of effluent so slowly that the system backs up into the tank.

Please review SEPTIC FAILURE CRITERIA where we describe the signs of septic system failure.

On 2018-11-10 by Dianne

If it was a failing Drainfield wouldn’t we see signs on top of the ground or wouldn’t we have a terrible odor?

On 2018-11-10 by (mod) - house drain backs up and drains slowly into the septic tank

Dianne

What you describe is most-likely

1. a clog in the main drain for the building

2. a clog in the septic tank outlet pipiing

3. a failing septic drainfield

On 2018-11-10 by Dianne

We have a septic tank and the pipe coming out from the house fills up and is very very slow to drain into the septic tank, also it will back up into the house if I wash a couple of loads of clothes. This pipe has a cap on it, one day it’s full and the next day it’s empty. What could be causing this?

On 2018-10-25 by (mod) -

Brian

The problem you can face is a sewage backup into your building when the septic system drainfield fails.

When there is no septic tank outlet tee raw sewage, including large solids, can flow out into the drainfield, clogging it and thus significantly-reducing its life.

On 2018-10-25 by brian

I have my septic tank but I never used tee what problem can I face

On 2018-07-09 by (mod) -

They all require a baffle or a tee

On 2018-07-09 by Bobby

Do all concrete Septic tanks have baffles. I don’t think mine has a wall in it

On 2018-06-24 by (mod) -

Yash

I don't have a shred of information about your system but perhaps your septic system drainfield is blocked, saturated, or failed. That would cause abnormally high sewage levels in the septic tank.

On 2018-06-24 by Yashpal

I have replaced it with new floater kit in septic tank even after adjusting water still over flows. What is the solution?

On 2018-04-17 by Rebecca Ellison

When it rains my tolite will not flush 4 days ?... It's a lovety situation, lol. What can ni do to fix it. I am under the grandfather Claus.what do legally in n.c.

On 2018-03-16 by Mel

Interesting, thanks.

On 2018-03-16 by (mod) -

Mel: repeat clogs at the septic tank inlet are often caused by improper drain line slope and inadequate wastewater velocity as the waste enters the septic tank. Clogging can also occur if the tee or baffle is improperly sized, installed, or constructed.

Before changing the baffle or tee I would have a plumber inspect the sewer line's slope and condition.

On 2018-03-15 by Mel

My wife and I moved into a newly constructed home with a septic tank in in late 2017. In that short time, the septic tank I nlet pipe has clogged 3 times at the baffle in 2 months with waste and toilet paper.

There is only a 3 inch clearance between the end of the straight inlet pvc pipe and the beginning of the baffle-seems short to me.

The pvc pipe could be cut back an inch or two while still allowing for proper inlet drainage into the tank. Is that a reasonable solution or is there such a thing as a larger baffle to increase the spacing? I’ve been in contact with the home builder in case of a warranty issue.

On 2018-03-15 by (mod) -

Mel: repeat clogs at the septic tank inlet are often caused by improper drain line slope and inadequate wastewater velocity as the waste enters the septic tank. Clogging can also occur if the tee or baffle is improperly sized, installed, or constructed.

Before changing the baffle or tee I would have a plumber inspect the sewer line's slope and condition.

On 2018-03-15 by Mel

My wife and I moved into a newly constructed home with a septic tank in in late 2017. In that short time, the septic tank I nlet pipe has clogged 3 times at the baffle in 2 months with waste and toilet paper.

There is only a 3 inch clearance between the end of the straight inlet pvc pipe and the beginning of the baffle-seems short to me. The pvc pipe could be cut back an inch or two while still allowing for proper inlet drainage into the tank.

Is that a reasonable solution or is there such a thing as a larger baffle to increase the spacing? I’ve been in contact with the home builder in case of a warranty issue.

On 2018-01-31 by (mod) - pump runs & effluent coming up out of monitoring ports

That sounds to me as if the piping or field are blocked. I'd ask for a camera scan of the lines.

On 2018-01-31 by Dean

I have a pressurized pump septic system, and while standing outside I noticed the sound of the pump running, and then effluent started coming out of two of the four monitoring ports. It was squirting out just above ground level and seemed to be coming out of the side of the 4" diameter pipe (monitoring ports).

Could they just be cracked and I just need to fix that, or does it indicate a larger problem? Is there supposed to be pressurized water there at those monitoring ports? Thanks .

On 2018-01-22 by (mod) -

Possibly, Bryan, but there are some questions of adequate depth, working space, and installation of a suitable trap as well as fitting the proper type of wyes, not tees (to avoid clogging)

On 2018-01-21 by Bryan

I am installing new bath. There is. 4" inspection port right outside. I dug down 4 feet to where it ties in to main sewer line. It has a sweep on it. Can I tie my new bath into this?

On 2018-01-14 by (mod) - why we need tank baffles or tees

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.

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

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.

On 2018-01-14 by Mike Ruyak

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 2017-12-08 by Rick

Hey, first off; thank you for posting this. This is one of the best informative reads, I've read.

However, just to be 100% clear: My inlet hole is lower in my concrete tank than the outlet hole, like u mentioned above.

Can I solve this problem just by figuring out the height difference between the holes and adding that difference to my outlet t baffle or do I have to drill out the cement and adjust the hole? I'm worried about cracking my tank, if using a hammer drill on it.

On 2017-12-04 by (mod) - a homemade miniature dry well with very limited capacity

Joe,

You are describing what I would call a homemade miniature dry well with very limited capacity. When the soil under and around a dry well has become clogged, the usual repair is to daisy chain a new one downstream from it.

You might want to search this website for DRYWELL DESIGN to see details about purchasing or building something that will be more effective and have a longer life.

On 2017-12-03 by Joe

The "after further research" comment is mine. I forgot to leave my name.

After further research, it appears that a poly 55 gallon drum is being used as a septic system for the washing machine discharge. I removed a bung and saw that the water level was just below where the PVC drain pipe enters the drum.

I don't believe that the drum is draining properly. If the drum holes for leaching are clogged, what can I do? Would muriatic acid help if there is lint clogging the holes?

On 2017-12-03 by (mod) - noticed water coming out of the pipe that enters the green tank.

Check the little green tank to see if it is a washing machine
filter that needs cleaning

On 2017-12-03 by Joe

During another drain cycle, I noticed water coming out of the pipe that enters the green tank.

I noticed water bubbling up (during the washing machine drain cycle) prior to entering the septic tank. I dug the dirt out and found a couple of pipes entering a green plastic tank (appears the waste enters this before the septic tank)

. I ran the washing machine again, and during the drain cycle, I heard air escaping and very little fluid from the pipe where it enters the green plastic tank. It did not appear that the pipe was glued where it entered; should it be? If not, what should I do?

On 2017-09-30 by (mod) -

I'm not sure what to expect as I don't know where the odor is occurring. If you're odor is indoors I suspect that they Plumbing vent system is inadequate or blocked.

On 2017-09-29 by Anonymous

Hi.... When we installed a sepitic tank pipeline connection.and when we are using also we are getting a smell from it. So please give us a suggestion to not to get a smell

On 2017-09-22 by Rick Brandt

Am installing new modular home on other side of septic tank.. What are considerations for entering tank on other end. IE moving inlet.

On 2017-08-08 by Brandy

How do I replace the inlet baffle on a septic tank

On 2017-06-05 by (mod) - citations on proper sewage levels & septic tank construction

• Sources include
  
  Septic Tank Sewage Levels: https://inspectapedia.com/septic/Septic_Tank_Sewage_Levels.php
  
• University of Michigan, Residential Sewage http://extension.missouri.edu/p/WQ402
  
• 19 CSR 20-3.060, Minimum Construction Standards for On-Site Sewage Disposal Systems, Missouri Department of Health, February 1996.
  
• On-site Wastewater Treatment and Disposal Systems Design Manual, U.S. Environmental Protection Agency, 1980.
  
• CI Pre-cast septic tanks - http://www.caymanprecast.com/ci-precast-utility-products.html
  
• Coate septic products - http://www.coateconcreteproducts.com/septic-tanks-dayton-area.html
  
• Milan vault Inc http://www.milanvault.com/septic-tanks/design-installation-consideration/ - NOTE HERE is a 6" difference inlet-outlet
  
• OAS, building drawing guidelines, http://www.oas.org/cdmp/document/codedraw/sectionf.htm
  
• Grimm Building -http://www.grimmbldg.com/precast_catalog.php
  
• Jensen Pre-Cast Concrete Septic Tank Measurements, http://www.jensenprecast.com/Septic-Tanks/Residential-Septic-Tanks-p4060/

On 2017-06-05 by (mod) - distances from tees to sewage etc in the septic tank

Good question, David. And there are opportunities to get confused.

The bottom of the outlet opening of a septic tank will be no less than 3" lower than bottom the inlet opening, - I got that number by examining a number of septic tank architectural drawings from septic tank manufacturers.

BUT: that's not the whole story: take great care to look at the bottom of the inlet baffle or tee will also be higher than the bottom of the outlet baffle tee.

Remember that in a properly-working septic tank the top of the waste in the tank will be at the level of the bottom of the outlet pipe that carries effluent to the drainfield, and the top of the waste will be (addressing yoru question) no less than an inch below the bottom of the inlet pipe, often more.

If there's not enough difference between inlet and outlet opening heights in the septic tank, baffles or tees notwithstanding, the tank outlet can become blocked and the system will back-up into the building it serves.

Typically, if we set the minimum working septic tank depth as (D) (engineers often use 36" as "D")
then

D = working depth = tank bottom to top of wastewater in the tank

0.2D = minimum extension DOWN of the inlet tee below the bottom of the septic tank inlet

0.4D = minimum extension DOWN of the outlet tee below the bottom of the tank inlet into the wastewater

And

0.2D = minimum extension of BOTH inlet and outlet tee or baffle above the wastewater level in the tank

and

4" = typical inlet and outlet PVC pipe diameter and openings
These are minimum numbers in my view.

Here are more "rules of thumb" for septic tank metrics:

The outlet tee should extend 24" down into the wastewater (below the bottom of the outlet opening)
The outlet tee should extend 12" upwards above the wastewater top level (above the top of the outlet opening)

The top of the inlet and outlet tee should be at least 1" below the under-side of the septic tank cover or top or access cover

The inlet tee or baffle should be at least 1" above the top of the inlet opening to the tank and thus 1" above the top of the inlet waste pipe entering the septic tank

The bottom of the waste pipe entering the septic tank from the building should be at least 3" above the top of waste in the septic tank, otherwise velocity of entering sewage and wastewater may be too low and the waste may not be able to enter the tank through the floating scum layer.

On 2017-06-05 by Gary

What is the distance from the center of the septic tank to the discharge baffle

On 2017-06-05 by David

How much lower should the outlet pipe be from the inter. On a septic tank

...

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

Or see these

Recommended Articles

• SEPTIC FAILURE SIGNS
• SEPTIC SYSTEM TROUBLE: WHAT GOES WRONG
• SEPTIC TANKS - home

Suggested citation for this web page

SEPTIC TANK TEE FAQs-2 at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

INDEX to RELATED ARTICLES: ARTICLE INDEX to SEPTIC SYSTEMS

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