Blocked drain or drain backup diagnosis FAQs:

Questions & answers on how to determine if a slow or blocked drain is caused by drain line blockage or caused by septic system failure.

This article series gives advice on how to diagnose and fix clogged or slow plumbing drains and how to recognize failures in a septic system.

Slow drain diagnosis: pipes or septic system FAQs

These questions & answers about how to tell the difference between a clogged drain line and a blocked, clogged, or failed septic system, were posted originally at CLOGGED DRAIN vs SEPTIC PROBLEM - topic home. Please see the diagnosis and repair advice found there.

[Click to enlarge any image]

Photo: oils like coconut oil that are liquid at warmer temperatures can cool and clog drain lines in cold weather.

On 2019-04-19 by (mod) - conditions under which a drain line will freeze.

Indeed a drain line can freeze if there is for example a slow leak into the main building drain during freezing weather. Of course other possibilities include surface runoff leaking into the septic tank and causing, in combination with a failed or blocked septic drain field, back up into the building.

On 2019-04-19 by Anna

Our septic tank had backed up grey water into our toilet and bathtub in February. It was very cold and we had not used our septic as our place is seasonal.
The septic tank was pumped in August so we are wondering if it froze.

On 2019-04-02 by (mod) - effect of cooking oil on septic drainfield

Small amounts of cooking oil in residential use ought not damage a septic drainfield, as it ought to be captured in the floating scum layer in the septic tank.

But you're quite right that coconut oil will solidify at low temperatures - I've seen that same effect in a jar of oil we keep on a bath shower window sill.

The melting point of hydrogenated coconut oil is 36–40 °C (97–104 °F).

So at temperatures below that it begins to gel into a white gloppy muck.

On 2019-03-16 by ann

@Cjris, I had the same problem after pumping my tank. Do you use coconut oil in cooking? I have a MIL conversion. My renter's kit sink stopped draining. Turns out she was running coconut oil down the drain from cooking, which solidified in her pipes. I had to pay a plumber to have them snaked. In the meantime, my 30yr old kit sink was running as slow as molasses. The fix was replacing the part of the u-pipe that goes through the wall, as it was clogged almost completely closed with gunk.

On 2019-02-04 by (mod) -

Sounds like frozen wayer supply pipes.

On 2019-02-04 by Shawna

Hi, our toilet won’t flush but our sinks drain. We have no water coming from our taps either. Do you think all those pipes are froze. Also I didn’t think our septic tank would be full already. Does one have to do with the other ? Could use some advice. Thanks

On 2019-01-31 by (mod) - Pumping a septic tank is not a proper repair for clogged drains. Liquid gold?

Belle

Pumping a septic tank is not a proper repair for clogged drains.

You may need a plumber with a power-snake to clear out the line between house and septic tank;

If your septic system is working properly, pumping the septic tank will not fix a clogged drain problem.

If the backup appears to be due to a backup and flooding in the septic tank itself then most-likley either the septic tank inlet/outlet are blocked or the drainfield has failed. In those cases pumping the tank gives a few days' relief but othewise fixes nothing whatsoever.

On 2019-01-30 by Belle

I recently had my brothernlaw over at the house, the same time, my son flushed one sheet of paper towel down, along with some extra toilet paper.

Now our system is backing up into the tub, we put liquid gold down through the tub drain, and it worked for a little while. Now this morning o went to do laundry and the laundry water drained into the tub?
Is it still clogged or should we have our septic drained again?

On 2018-09-30 by (mod) - pumping the septic tank won't usually affect just one plumbing fixture

I wouldn't expect pumping a septic tank to ever affect the drainage from one single fixture and a house shortly not causing it to fail to drain

unless that fixture has a separate outdoor drain line towards the septic tank that was run over and crushed or damaged by people working in the yard.

or possibly if it's the lowest plumbing fixture in the building and thus the first to respond to a clogged septic system or sewer line

On 2018-09-30 by Cjris

We had our septic pumped yesterday. All the drains worl fine but the kitchen sink.

It was fine before it was pumped. Now it is very slow or comes up in the other sink. What can i do? I plunged it used liquid plummer.

On 2018-08-05 by Anonymous

@Jennifer,
Have your husband run a different pipe from the washer water into your yard somewhere.

Dig a 6 ft-8ft trench, 2 feet down, put peastone in it and run the pipe into that. You'll never have backed up septic again unless the outside water table gets really high from rain.

On 2018-07-13 13:59:56.263041 by (mod) - how to fix a flooded septic system

Steve

Please see FLOODED SEPTIC SYSTEMS, REPAIR

Where we will repeat your question and give a detailed answer.

On 2018-07-13 by Steve Gray

I have A septic that is not in being used.It was attached to A moble home 10 years ago..I had it pumped about A year ago for the heck of it.

I noticed sewage on the ground after a heavy rain and when I removed the cap water poured out.I'm assuming the fill line is stopped up but can someone tell me what the best way to fix this.

On 2018-03-29 by Rachelle

Can a septic tank get clogged from just having 4-5 people over a 4 day period...
having 4-5xtra people using water,t.p.
.or does it happen over a period of time?

On 2018-03-16 by (mod) - We just had out septic tank pumped a month or so ago,

Jennifer

PUmping the septic tank is necessary to protect the drainfield but it will NEVER fix an actual problem such as a clogged drain or failed septic field. You get at most a few days relief while the septic tank is re-filling.

RidX will not fix the problem. You need an onsite septic expert contractor to do some diagnosis starting at the tank and distribution box.

Search InspectApedia.com for SEPTIC ADDITIVES to read about those products.

On 2018-03-13 by Jennifer

We just had out septic tank pumped a month or so ago, because the water from our washing machine was backing up into our downstairs toilet and flooding our bathroom. Once it was pumped, the problem stopped, until now.

Again when we do laundry the water backs up into the toilet and floods.

Once the water goes back down, the toilet flushes and operates fine. As well as all other toilets and plumbing in our house. We do not flush anything other than toilet paper and I can't imagine the tank needing pumped again so soon.

No septic odor or foul water bacling up.. simply the water from washing machine backing up into toilet rather than draining properly. I just bought and applied Rid X.. Hoping this helps. ANY other advice? We've recently moved here and I'm not super familiar with septic systems.

On 2018-03-09 by (mod) -

Roots and mud in a drain line mean the line is open to the earth around it, has failed, and needs to be repaired.

Even cleaning it out won't be a lasting repair. Dirt and roots just find their way back in.

On 2018-03-08 by Tracie

Kitchen sink either drains slow or water sits in both sink for a while then drains. Can not run water for more than a few minutes before it starts to back up. No problems with any other plumbing in the house. Had the kitchen pipe snaked and they said there were some roots and mud in the line. Drained better for about a week, then slow again. Any ideas what the cause is???

On 2018-01-07 by (mod) -

Dave

If a drain piping system is properly installed, sized, and designed (in diameter, use of proper wyes, slope 1/8" to 1/4" per foot) then it should not be clogging with a reduced flush toilet. It might be worth sending a sewer line camera thorugh the rain to look for a slope problem or a partial blockage.

On 2018-01-07 21:18:01.810521 by Dave

I bought 0 .8 gallons per flush wanting to conserve water consumption my drain system backed up twice cleaned it out both times did some research and found out that my drain system needs full 1 .6 gallon flush to carry waist all the way out

On 2018-01-05 18:48:29.277896 by (mod) -

Start with a plumber who can unblock your main drain

On 2018-01-05 06:16:26.938132 by Charlotte

My drain on my basement backed up and about a week later my sink backed up and now they are both backed up and wont drain. What could it be? And what could i do to fix it?

On 2017-12-19 13:46:34.822032 by (mod) -

That sounds to me as if the building main drain is partly blocked and that water is entering the drain from somewhere else in the building.

Another possibility would be a failure in a septic system that uses an effluent pump or an aerobic system using a dosing pump that's cycling but unable to pump water out due to a failure or blockage.

On 2017-12-19 13:45:25.423459 by (mod) -

That sounds to me as if the building main drain is partly blocked and that water is entering the drain from somewhere else in the building.

On 2017-12-18 14:09:26.023329 by Humdec

Septic water is coming back up in toilet. Then it goes down completely, then backup and empty completely. Every 2 or 3 minutes. What's causing this?

On 2017-10-30 by (mod) - signs of a clogged drain

Paul

From your description this sounds like a clogged drain, I agree.

An inspection of the sewage levels in the septic tank and distribution box can confirm that by an absence of abnormally-high sewage or effluent levels at those locations.

Articles in the ARTICLE INDEX describe HOW TO FIND the SEPTIC TANK

and HOW TO FIND THE D-BOX if you need that help.

That's a reasonable place to start: hire a drain cleaning service who can also inspect the drain system for types and location(s) of blockages. Let me know what you're told.

On 2017-10-30 by paul

forgot to tell you that after inspecting the well and septic area on property i do not see any floodind or water or smell anything unusual

we moved into a 2 level home ,have had no problems for 6 months now we have 2 upstair full bathrooms and 1 half bath downstairs i have always had sewer in past years but 1 upstair b/r is working fine including toilet ,shower /and sink the other upsyairs toilet seems like there is a clog between that upstair and downstairs .

we replaced downstairs toilet and tank with a new one but we do not have much of a flush when we use a plunger we have backup in shower then we clean it and water goes down from shower so it seems there is a clog between upstairs b/r and this half b/r the septic was just cleaned and pumped 2yrs ago.

i am not sure to call plumber or septic

On 2017-10-10 by (mod) - A septic field can be saturated but still passing out effluent slowly enough that we don't immediately see a backup

Good question Anon. A septic field can be saturated but still passing out effluent slowly enough that we don't immediately see a backup in the building that it supports. But it's a safe bet that we're headed for a sewage backup - typically occurring when the system is loaded more heavily by having many occupants in the building or by wet weather that further floods the fields.

Standing water over the septic tank sounds like a problem in any case: local groundwater flooding the tank will flood the tank and drainfields even if it's not coming out of the building as sewage effluent. The septic system cannot work under that condition and there is also a risk of backup.

On 2017-10-09 by Anonymous

Anonymous from 3 hrs ago, sorrry my name is Kelly, I felt I should add and clarify a few things pertaining to my earlier post.

We had our septic tank pumped because water was standing in the area of the septic tank, the water however has been clear water and thete has been no foul sewer stinch, I said it had filled back up in 2 days,

well I'm assuming it has filled back up because the water started standing again in the same area as before, the water is clear though and does not smell, hope this is a little clearer! Thanks!

On 2017-10-09 by Anonymous

If your septic leach field lines are full wouldn't you have sewer back up in house, we aren't having any problems in the house but water standing on septic tank,

had it drained and it filled up in two days, but water is clear on top of ground, does not smell like sewer and did not smell like sewer before we had it drained, could we have a water pipe leak , instead of sewer priblem??

On 2017-10-09 by (mod) - it's not normal to see water running continually in a drain line

No, Mike, it's not normal to see water running continually in a drain line. I suspect that a toilet is running somewhere. Try turning off water supply to the toilets then turning it back on one by one. (Another possibility is a partially-blocked drain line, or some other water usage source like a water softener).

On 2017-10-09 by Mike

We have a drain clean out and can see water running after a flush. We put in a wad of TP on all three toilets but can never see that just the water...is that normal?

On 2017-09-26 by Princess

I have a well system, septic, I have 2 bathrooms, everything is draining just fine, except for the toilet in my master bedroom, could the septic be clogged if only one toilet won't flush? When flushed it just fills the bowl up with water, after some time it goes down bit won't flush completely

On 2017-08-20 by (mod) -

Cindy the article CLOGGED DRAIN vs SEPTIC PROBLEM is my best explanation of how to sort out your question. Was that too long, confusing, or just annoying? Your critique will help me make the information more useful and usable.

In short, if all drains clog with the same amount of wastewater flowing into them, then it's either a bad septic OR a clog in the house main drain.
If just some drains clog then the problem is probably closer to the clogging fixture.

On 2017-08-20 by Cindy

Slow drain in shower and toilet, is it septic system or just a clog

On 2017-08-05 by Christa

Sorry that last post was mine. Not sure why it posted as anonymous.

Yes I did remove both of the traps and cleaned them . I have also plunged both sinks. I purchased a snake from the local hardware as well and tried to snake it. I can get the snake completely through both. I'm at a loss for what could be causing this to happen.

On 2017-08-02 by (mod) - kitchen sink was clogged/ draining extremely slowly

The good news is that what you describe sounds like a local drain problem. That would not be a septic system issue - if the septic were the problem I'd expect all of the drains to slow or back up.

Unfortunately the baking soda powder, if it was too much, may have added to a solid blockage.

Have you tried using a plunger?

If the blockage is in the trap, removing and replacing the trap might be a solution.

Keep me posted.

On 2017-08-02 by Christa

My kitchen sink was clogged/ draining extreamly slow in the hoe we just moved into. The bathroom sink, toilet, and bathtub all drained fine. I put vinegar and baking soda in the kitchen drain to try to clear it.

The next day i tried to plunge the kitchen sink. Once I started to plunge the kitchen sink it backed up in the bathroom sink. Now both sinks are blocked and will not drain at all. However the toilet and bathtub are fine. The bathroom sink smells of sewage. (very disgusting)

Could this be my septic needs needs emptied. I live in a mobile home.

On 2017-07-18 by (mod) - how to fibure out if the blockage is the drain or the septic tank

Donna,

It sounds as if wet weather has flooded the septic tank or drainfield or both. If so, the bad news is that significant work is needed.

If all building drains are slow or clogged, or if waste is backing up into the building from the lowest plumbing fixture, you would suspect the sewer line is blocked or there is a failing or blocked onsite waste disposal system (septic system).

On 2017-07-18 by Donna

We been having a lot of rain the past few days. Today my mom did some laundry and later found stuff in her bathtub(looks like water backed up) we have a septic tank. I'm not sure if there is a pipe clogged or if from all the rain the septic is full of water.

Is there a way I can figure it out myself? Don't have hundreds of dollars to call someone please help thanks

On 2017-07-01 by (mod) - main drain is blocked downstream of the point at which both toilet and shower empty into the drain system

Mike,

Most likely the main drain is blocked downstream of the point at which both toilet and shower empty into the drain system. Or if there is no blockage in the building drain itself then the blockage is at the septic tank or in failed septic fields. The article CLOGGED DRAIN vs SEPTIC PROBLEM helps sort out whether the problem is in the building drain or in the septic system.

On 2017-07-01 by Mike

What does it mean when you have a septic system when you flush the toilet and it backs up into the shower

On 2017-05-27 by Izzy

I realize this might be a stupid question, but I'm moving into a third-floor apartment in Maryland, and wondering if I should bother getting the optional Water and Sewage coverage in my renter's insurance.

It "covers damages to a Resident's possessions when water backs up from a sewer or sump pump.

This endorsement applies when there is an issue with the sewage line from the street that causes the sewage to flow back into the apartment. It does not cover flooding, seepage, etc."
Are backups just a problem for basement/ground floor apartments? Thanks.

On 2017-05-02 by Tabatha

My bath tubs and toilets are filling up with water but not sewage is this just a clog?

On 2017-04-19 by (mod) - time to use a sewer camera to inspect the drain line

It sounds to me as if the drain is blocked. Perhaps your plumber can use a sewer camera to find the blockage or damage.

On 2017-04-19 0 by Jon

House on slab septic tank pumped out. Problem is washing machine drains into bathtubs.only 1 vent for housI've had 2 plumbers check it out,they didn't know. I think it needs more vents.HELP PLEASE

On 2017-03-27 by (mod) - clearance requirements of drain or sewer lines to property lines

Not a system I know - in looking I found

https://www.colorado.gov/pacific/sites/default/files/WQ-ENG-WQCD_20120915_WPC-DR-1_WW_Design_Criteria_Final.pdf for Colorado.

and a number of other discussions of this type of wastewater treatment such as

https://www.pca.state.mn.us/sites/default/files/wpc-40sonar1-99.pdf a more academic article.

You've clarified the drain line vs. property line question - thanks.

Blocking a sewage effluent outlet while continuing to run waste into just about any septic tank or treatment system can cause trouble ranging from backups into the building to pushing the floating scum layer into an outlet tee or over an outlet baffle;

IF that is what happened at your system then solids could have been pushed into the line to the drainfield or into the drainfield itself.

I'd suggest opening the tank to inspect the inlet and outlet baffles for signs of recent overflow.

Do keep me posted - what you find will help others. To send photos of the system and its investigation you can find our email at the page top or bottom CONTACT link.

On 2017-03-27 by Jackie

Thanks Daniel it's a W.P.C. Type A unit with filter, media, distributor, pump, control equipment and baffles. It has been working beautifully since 1982 and since we brought the property in 2002 . We had it serviced last year and a new pump put in.

Our property was built by the people that owned next door and the deeds give rights for the discharge drain to run through their garden to the ditch at the bottom.

They have since sold the piece of land with the discharge drain to developers who are putting up two houses. They said they had to block off the drain and relocate it to the new run between the two new plots. I

was just wondering if blocking the drain for the time they needed to reconnect it to the new route has cause it to back up and damage our unit? It has always discharged clear water and now it's not. It seems to be flowing fine but not filtering properly.

I've been waiting for an engineer to ring back. Thank you for your help.

On 2017-03-27 by (mod) - builders next door did something to our septic or sewer line?

Jackie I'm not clear on what happened, what's damaged, what repairs are needed.

1. In most jurisdictions it would not be permitted for sewer lines from house to septic tank nor from tank to soakbed to be off of your own property (plot) so I'm confused about why a builder on an adjoining property would touch your system at all.

Certainly they ought not be driving equipment across your land as the risk is damaging or destroying the septic system

2. You need to find out exactly what was done as well as the current state of the system by direct inspection - I'm not very smart anyway but certainly I can't see your property from here at my lab.

From your comments it sounds as if you r septic system uses a pump - I don't know where the pump is,

what its pumping, where it's pumping to: sewage grinder pump to an uphill septic tank? An aerobic system? or an effluent pump to an uphill drainfield?

There is also a possibility that the line relocation not only left damaged or leaky piping but piping not properly sloped to drain properly.

You need onsite expertise: and probably some digging, to see what happened to the system and its piping, starting at the septic tank.

Daniel

On 2017-03-27 by Jackie

Hello the builders in the plot next door had to re-locate our discharge pipe to our septic tank. Since then the tank has been discharging dirty waste. The builders said the blocked the drain off whilst relocating.

Could they have damaged the pump or the circuit board if the tank had been allowed to back up into the chambers? Thanks

On 2017-01-28 by Greg

Basement toilet has been gurgling for about a week. We've recently had the septic emptied (within the last year) I've taken the toilet off and snaked what I believe to be all the way into the tank (6ft snake) with no problem so I don't suspect a clog. Do you think the septic could be full?

On 2017-01-23 by Mark

Septic tanks were pumped last week. Its been raining really hard for days and toilets wont flush for hours then will flush maybe couple times. The cleanout is full of water and i ran a snake to the tank .

On 2016-12-30 by (mod) - local drain blockage close to the toilet

Jeff, that sounds like a local drain blockage close to the toilet.

On 2016-12-30 by (mod) -

RE-posting

Ken Riddell said:
Various reason can be there for clogged drain lines.

Cleaning out plumbing services will fix your clogged or damaged sewer and drain lines quickly. You may refer to some plumbing services company which provide drain cleaning in south jersey that will be helpful for your problem.

On 2016-12-29 by Jeff

Only one toilet in our house is not flushing. Black contents in toilet and in the basement right below the toilet, water is coming out of the pipes.

On 2016-06-04 by (mod) - blockage pretty far down the drain system

Sounds like a blockage pretty far down the drain system or at the septic tank itself; that can happen by a pipe blockage, D-box blockage, or septic tank backflow from a failed drainfield. Your onsite inspector will want to open and look into the septic tank and Distribution box

On 2016-06-04 by A sudden Clog that is effecting our 2 bathrooms!

I took a shower first. There was no problem. Then my husband gets in and the tub starts to fill and wont drain. We then discover our guest bathroom toilet and shower are clogged too. There was no slow draining, no noises, nothing.

We located the septic and opened it. The water barely trickles out to the septic after flushing the toilet. So we figure the clog is a main pipe leading to the septic. We used a hand snake (25ft). We snaked both showers and toilets. Still its clogged. Any suggetions? Why would it clog so suddenly?

On 2016-04-19 by (mod) - Pumping a septic tank will never fix a clogged line nor a sewage backup

Perplexed

Pumping a septic tank, while critical for preserving septic drainfield life, will never fix a clogged line nor a sewage backup; at most it gives a few days of relief (while the septic tank refills from normal use) if the problem was a clogged septic tank outlet or failed drainfield.

Snaking a sewer line does not always remove blockages, particularly if it's just partial. Then a big blob of toilet paper combined with a volume of wastewater used can cause a sewage backup.

If all drains are slow or if the backup occurs in the lowest part of the building, I suspect the blockage is in the building main drain.

Perhaps your plumber can run a camera to inspect the drainline.

On 2016-04-19 by Perplexed

My drains toilets and pipes have been snaked, the tank does not need emptied ( was told by our septic guy), but we have back up! What could be the problem? there has been recent renos done to the house, a bathroom and kitchen added.

...

Continue reading  at CLOGGED DRAIN vs SEPTIC PROBLEM - topic home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Plumbing Drain Articles

• CLEANOUTS, PLUMBING DRAIN
• CLOGGED DRAIN DIAGNOSIS & REPAIR - home
  • BLOCKED DRAIN REPAIR METHODS
  • CLOGGED DRAIN vs SEPTIC PROBLEM
  • CLOGGED DRAIN DIAGNOSTIC CHART
  • FIXTURE vs SYSTEM DRAIN BLOCKAGE
  • KINETIC WATER RAM
  • POWER SNAKE DRAIN MACHINES
• CLOGGED SUPPLY PIPES, DIAGNOSIS
• CROSS CONNECTIONS, PLUMBING
• DRAIN & SEWER PIPING - home
• SEPTIC BACKUP PREVENTION
• SEPTIC BACKUP REPAIR - home
• SEWER GAS ODORS

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