Photograph of a multi-S-trap plumbing fiasco Plumbing Drain Noise FAQs #3
More Q&A on plumbing drain noises

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Plumbing drain noise diagnostic FAQs:

Frequently-asked questions & answers about the types, causes, & remedies for plumbing drain noises & sounds.

This article series explains how to determine the causes of plumbing drain noises, and we refer to key companion articles that assist in that diagnosis, and we include plumbing noise cures.

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How to Diagnose Sounds of Gurgling or Other Noises in a Building Drain Piping System

Dishwasher drain hookup to sink trap tailpiece (C) Daniel Friedman InspecApedia.comRecent Reader Questions & Answers about Plumbing Drain Sounds posted either at the end of this article or at the topic home PLUMBING DRAIN NOISE DIAGNOSIS

On 2017-11-20 by (mod) - why is water running in our sink drain when the sink isn't in use?


Depending on brand, model, age, a refrigerator might drain during defrost cycle, but usually that just spills into a pan in the fridge base where it is "disposed-of" by evaporation.

Still, 1/4" is so small that I'd bet on a refrigerator or A/C condensate drain line or maybe, depending on how the water filter works, filter wastewater (such as from an RO system).

Below in my first test of a new Comments Box feature I'm clicking the little image icon next to the "Comment" button to see if I can drag in a photo of a more-typical under-sink appliance drain connection into the sink drain tailpipe.

You could test the theory by turning off the water supply to your refrigerator for a bit.

On 2017-11-20 by thomasmyers21

Thanks, mod. I totally get that. When I look at the connections under the sink I can see a small (maybe 1/4" diameter) black plastic hose connected directly to the drain pipe about 5 inches down from the drain base.

I cannot tell where this line runs to, however. With my fingers it feels as though it parallels the copper water line that runs to the refrigerator, but cannot be certain. I confess that I don't have a good knowledge of how the refrigerator water system works

. Our fridge has a filtered water system for drinking water and ice making. With that said, are you saying that there is a problem perhaps with the refrigeration filtration system or something??

On 2017-11-20 by (mod) - where's the drained-water coming from?


A sink cannot be draining water unless there is water to be drained. Take a look under the sink to see if there are not connections to its drain line such as water from a refrigerator condensate drain, a dishwasher, an air conditioner condensate drain.

On 2017-11-20 by thomasmyers21

Hi - our kitchen sink will spontaneously start draining water when there's no water in the sink nor is the faucet running. This is a dual sink and I am able to peer into the drain and visually see the water trickling through the drain.

Just prior to this we had our septic lines cleaned and also prior to this we could hear air knocks in the lines. What could be causing this?

The ONLY thing that makes sense to me could be that the refrigerator water system is flowing back into the sink, because I cannot figure any other source where the water could be coming from. I've tried shutting off all the valves under the sink when I see this happening.

On 2017-10-24 by vee

Please help , gurgling noise always in washer dryer unit in highrise condo

On 2017-09-19 by (mod) - water supply pipe vibration sources

Typically that's a water supply pipe vibration due to the water velocity, pipe size, routing, length, elbows, and other factors. Often a simple small change in the velocity made by party closing the main water supply valve will fix the problem. That's a good place to start. Details are at WATER SUPPLY PIPE WHISTLE NOISE

On 2017-09-18 by Alice

Hello, the pipes in our bathroom (before once a day, now worryingly more frequently) have been making a horrendously loud, vibrating / throbbing sound that lasts for over a minute (used to be more like 30 seconds, now more like 2 minutes).

The noise has happened after we use the bathroom but also, and more often, tends to wake me up between 1 and 5 am. I've lived here 4 months and this has been the past week only, do you have any suggestions as to what it could be? We obviously need a plumber to come check but I'm panicking in the meanwhile. Honestly, it's loud enough to be genuinely a bit scary, not a noise I like any part of a house making, can't think what the neighbours think. Thanks so much for any help!

On 2017-07-24 by (mod) - sources of water backflow into a sewage pump or ejector pump making it run "for no reason"

Wow, several hours, how odd. Is there at your property:

a sewage ejector or sewage pump system that is cycling on later is most-likely being triggered by

On 2017-07-22 by Terry Medearis

After turning off a bathtub shower and waiting several hours, a vacuum sound comes from the fixture. If I turn the bathtub water on-off quickly, the vacuum sound goes away, only to return several hours later. Any idea what might cause this?

On 2017-07-17 by (mod) - test to see where gurgling sound is coming from

Try pouring a bucket of water, or running a lot of water, into that same sink and see if that also causes a gurgling sound.

Separately when the sink is empty, try flushing the nearby toilet to see if that causes a gurgling sound at the same sink drain. If neither of those events causes gurgling then you are hearing the trickling sound of the condensate draining into the fixture but there is probably not a drain blockage nor a ventng defect

On 2017-07-17 by Nathan

Ok that makes sense. I've noticed now too a slight gurgling in where the ac unit is and this is the sink that the ac drains into. I seem to be the only unit this is happening to. I'm not sure if there's anything I can do about that.

On 2017-07-17 by (mod) - A/C condensate drainage as drain noise source

Good sleuthing. So try temporarily re-routing the A/C condensate as a diagnostic step. If you're in a hot humid climate it's possible that quite a bit of condensate production is continuous.

On 2017-07-16 by Nathan

Ok so I have some more variables here. The bathroom sink that is gurgling is also hooked up to my AC condensation line. And I heard it gurgling a little this morning when I woke up. The sink drain hasn't stopped gurgling in 3 days.

Photograph of a plumbing vent blocked by a visiting frog

On 2017-07-16 by (mod) - a partly blocked drain can cause drain noises

No Nathan. A partially-blocked drain, particularly if the blockage is pretty far distant from the fixtures or even outside and distant from the building itself, will accept a considerable volume of wastewater, say several toilet flushes in succession, without backing up into the building.

But wastewater "stored" in the waste line upstream from the blockage will then continue to seep through the blockage and give the gurgling you describe. That problem is more likely to be noticed if venting is also inadequate - the seepage of waste past the blockage creates a vacuum behind it (upstream).

If venting is working air is drawn into the waste piping and building plumbing drain traps remain silent and un-bothered. But if venting is blocked or inadequate, that vacuum "sucks" air into the drain system from the building, down through sink, shower, or tub traps and thus, as air passes through those water-filled traps, the gurgling may appear right at the fixture.

Gurgling may continue for some time as wastewater continues to drain past the blockage, even when the fixture isn't in use.

If after hours of no water being run at fixtures you still hear the sound I suspect that there is water entering the drain system somewhere that has escaped attention, such as
- a running toilet
- roof drainage into the waste pipe system
- groundwater leaking into a septic system or wastepipe system

On 2017-07-16 by Anonymous

ok but if it was clogged wouldn't it be backing up some? It drains perfectly just has a constant gurgling sound that doesn't stop ever and is getting louder.

On 2017-07-15 13:11:20.511741 by (mod) - drain clogs are more-common than vent clogs


Drain plugs are in my view much more common than vent clogs (unless it's a wet vent that also handles drainage). That's because of vent pipe in most Plumbing Systems is normally open and filled just with air while drains have Solid Waste flowing through them and are more prone to blockage.

So on my view I always start by attempting to clear a clogged drain. If plunging a toilet or a sink or a tub or shower drain doesn't clear it after a few minutes of trying I might then need to actually have the drain snaked or cleared with a power auger. If you use the inspectapedia search box above to find out article on kinetic water Ram you may find another neat tool that can often clear a blocked drain

On 2017-07-15 by Nathan

I've been living in this upstairs apartment for about 3 months now and just this week the bathroom drain has been glug gluging. It started real quiet and has been getting progressively louder. I now have to close the bathroom door and can still hear it

. I've done some research and people say it's probably the vent pipe or drain pipe clog/partial. My question is. How do I find out what one it is? Drain or vent? I'm on the second floor and it's technically a condo so no on site maintenance. Please help.

On 2017-05-16 by (mod) - Pumping the septic tank will never fix a clogged drain nor a failed draonfield.

Pumping the septic tank, while required to preserve the drain field, will never fix a clogged drain nor a failed draonfield. A septic tank, in nomal use, is always full..

What we don't know is if the clog is between your house and tank or rather if the draonfield is failing.

Motor noise that you hear sounds like a sewage ejector pump

On 2017-05-16 by Kristy

Live in Florida, been in home 13 years, have septic tank with sump pump tank and no filter between the two, never had to pump tank out until today. Kitchen sink has its own pipe to the main pipe running to the solids tank. Started to back up after few seconds of running water.

Snaked it 3 times, draino it twice. Thought it was just septic need pumping. Note V both full bathrooms drain fine. Started hearing what sounds like a motor, possibly the sump pump, running in the sink drain after the water would go down.

After septic was pumped today the sink was still clogged? Snaked it again and water appears to be draining only we hear this motor type sound coming up from the drain and is rather loud? NEVER heard this sound before after 13 years? What is it?? Husband says its the sump pump, so why have we never heard it before?

There's no baffle down low in the tank only at the top going to sump pump section. I disagree with him only because I know I have not run 1000 gallons of water in a few hours to fill tank and cause pump to kick on. What in the world could this be??? Please help so I don't feel like I'm starting to just hear things that were never there before? Lol

On 2017-05-06 by (mod) - why does kitchen sink noise change?


If the noise is coming from the plumbing drain, I suspect that we're seeing a difference in the rate of flow of water into the drain. If the noise is coming from the supply piping I suspect that when you move your sprayer you are thinking a flexible line under the sink and reducing the water flow rate.

On 2017-05-04 by babygirl

why does the kitchen sink make a diffrent nosie when i spray the spout in a diffrent spot

On 2017-04-24 by (mod) re: kitchen sink bubbles my toilet bubbles when my shower is on


It sounds as if the vent for the drain system you describe is clogged or incomplete, but it also sounds as if the main drain or toilet drain is clogged. If plunging for a while with a toilet plunger doesn't fix the problem start at BLOCKED DRAIN REPAIR METHODS

On 2017-04-24 by D

My kitchen sink bubbles my toilet bubbles when my shower is on and shower is clog up and water is staying in it toilet running overs please help me

On 2017-04-23 by (mod) re: After a hard rain dishwasher flooded

TR Yes what you suggest is possible - moreso if your home is connected to a private septic system.

On 2017-04-23 TRowe

Recently I had 2 odd things happen. After a hard rain I used my dishwasher as usual and it flooded. Thinking it was a fluke I got the water up after inspecting the dishwasher. I washed clothes all day and at the end of the day once again ran another load in the dishwasher while also washing a load of clothes.

The next thing I know the house is flooded. I think this was probably caused by a slow drain from the recent rain. Is that possible?

On 2017-04-19 by (mod) re: washer and its drainpipe, smell like sewer.

I suspect the drain is not vented,and it may also not be a proper destination for the washer drain.

On 2017-04-19 by Libby

My washer and its drainpipe, smell like sewer. The floor drain 5 ft from the washer waste line gurgles or makes sucking noise. Dehumidifier, AC and air exchanger have hoses draining into the this floor drain. Put water into floor drain, still makes noise.

On 2017-04-03 by (mod) re: low running noise in a home

I don't know, from just y our e-text, anon, what is causing a "low running noise" in your home. If you mean running water, I'd start by shutting off each plumbing fixture individually - that can diagnose the source, such as a running toilet.

On 2017-04-03 by Anonymous

We had new pipes installed in our home recently and now have a low running noise that I don't know where it is coming from. Could it be the new pipes?

On 2017-03-27 23:07:12.476657 by (mod) re: signs of a clogged drain or blocked vent show up at the kitchen sink when washing machine runs


Usually the problem is either a clogged drain or a defective or blocked vent. It sounds to me as if the kitchen sink drain comes down to a point where the washer drain joins it and then continues out of the building - if so I suspect that the vent is inadequate, missing, or clogged; the added drain volume of the washer flowing through the drain system creates a vacuum that is burbling back up through the sink because it's air -starved.

Most washers empty into a standpipe that acts as an indoor Vent. It's possible that your washer drain hose is tightly fit or even sealed into its standpipe, exacerbating the drain problem.

You may need added venting on the washer drain.

On 2017-03-27 by Carolyn

Help please my kitchen sink above the laundry room gurgle each time the washing machine empty! It is only the sink in the kitchen and not to the bathroom next to the laundry room It drains fine so the noise is only in the kitchen drain !!!

Been in the house 40 years and this problem is 2years old . I had a clog in 2015 and 2016 Plummer said it was from the wrong t paper so I switched!' And now that noise is back but drains run fine
Any thoughts that you can help me with
Oh yeah my second floor bathroom is fine also!! Just the noise in the kitchen from the washing machine

On 2017-03-18 by (mod) re: signs of inadequate venting of a sink or lav

Alex it sounds to me as if the way the sink drains are arranged one of them is inadequately vented. I speculate that using the sink that is more-remote from the actual drain line is when you hear the problem. But it could go either way. If the sink pair is inadequately vented, water passing down one of the drains may be creating enough vacuum to draw air in through the sister sink trap.

On 2017-03-17 by Alex

I wanted to clarify my previous comment I have two sinks next to each other both drain perfectly when you run one and not the other there's a bubbling noise coming out of the other drain. When I run the water in the other one that noise goes away. And if you run the one that has the bubbling noise and not the other one there is no bubbling in that other sink.

We have two bathroom sinks next to each other. Both work fine but when one of them is Only and not the other always same one) , there is a bubbling noise in the drain of the other sink not being used. If you run water in the other sink at the same time the bubbling noise goes away. and it IS NOT the same the other way around. Why is that both drains drain perfectly,

On 2017-02-22 by (mod) re: signs of a blocked or clogged soakaway bed or leach field

A failed or blocked septic drainfield

On 2017-02-21 by Mary

A vent pipe, located in the drain field occasionally has water pouring from it. What can cause this?

On 2017-02-14 by (mod) re: water pools in the shower and in the yard


Unlike Johnny Carson's Magician the Great Carno, I can't really see what's going on at your home, what plumbing system piping, drains, routing, vents, leaks or blockages are occurring as your message is (nicely) brief.

But I am GUESSING that your main drain is blocked (or if you're on septic, the tank or drainfield are blocked or in failure).

That might indeed cause drainage to back up to a level at which it empties at a vent opening the the drain system that is sometimes found on some buildings in a building wall or at an inspection port along the run of a sewer or septic line.

Time to call a plumber.

On 2017-02-14 by Vee

Water pours out of the drain on the side of our house when we use the shower.

For the first time today, the water actually pooled on top of drain after all shower water ran down the yard.

Why would the water come up out of drain and down the yard ?

On 2017-02-15 by (mod) re: mobile home drain noise diagnosis and repair


Sounds to me as if either a drain remains clogged or a septic system is blocked or has failed. Sometimes in cold weather a drain may be blocked or partly-blocked by freezing-up. A plumber with a sewer line camera can usually find the trouble spot.

On 2017-02-13 by Megan

Recently we been having problems with our drains, we leave in a mobile home park,

I first noticed it when the toilet would flush the kitchen sink would gurgle, I informed our landlord about it and the maitence guy came and check things out, but of course it wasn't making any noises, he replaced the air vent thing to the kitchen sink drain, and it didn't do it again for a couple days, then started back up

, first the kitchen sink would gurgle, then later when my son took a bath and use the toilet shortly after and when he flushed it overflowed, and we noticed the tub didn't drain, plunging didn't help any, and it randomly drained by its self,

not sure what could be causing this problem, since it has drained its self the toilet keeps gurgling, and we ran the tub to see if it would drain and it did but then the toilet started gurgling again.
Also have high windy weather

On 2017-02-03 by Sherri

I have an older single wide mobile home and as I sit here I can hear water going through my pipes like it's pouring but I don't have any water turned on nor have I all day long. Why is this

On 2017-01-15 by (mod) re: plumbing noises from the toilet sound like it is self-flushing

Even changing a toilet flapper valve does not necessarily guarantee that you have fixed a slow, subtle leak out of the tank into the toilet bowl - that will ultimately lead to a minor self-flush. That's because the seal of the flapper to the valve base may still be poor unless the entire assembly is replaced. You're just replacing the flapper itself, not the seat to which it must seal.

Two things to try: dark food coloring (or septic dye) in the toilet tank may show up a leak in colour after a time. Or buy a new toilet fill valve from Fluidmaster - the model that includes a new feature: the valve will not drop and re-fill the tank if the tank is leaking. It only re-fills the tank in response to movement of the flush lever.

With that valve in place, if the tank is leaking it will indeed slowly leak out, but when you next check the toilet you'll find the tank low or empty.

Look for the Fluidmaster 400LSR Universal Fill Valve with Leak Guard.

InspectAPedia is an independent publisher of building, environmental, and forensic inspection, diagnosis, and repair information provided free to the public - we have no business nor financial connection with any manufacturer or service provider discussed at our website.

On 2017-01-15 by Help please !

House is 8 yrs old. On septic. We have two bathrooms. The one adjoining our bedroom (used the least) which is at the end of the house occasionally sounds like it tries to do a minor flush. I was thinking possible ball cock assembly or flapper

. The flapper has been changed a few times. Not the assembly. Nor has the septic been emptied as just my husband and I. What's weird is that sometimes...days on end.... when ever water is run at any point in the house even if that particular drain where the water is run is "closed off" at the time, when the water is turned off, it sounds in this one toilet like water is sloshing against the side.

I am so at a loss and quite worried as the inspector told our Government builders that if they ever used that Plummer again, he'd never inspect another of their houses.

Though he let ours through. Ohhh the troubles we've had. Shiver, shiver. I mean Who puts overhead plumbing in the walls and then runs outer wall insulation beneath the pipes instead of outside of them. That give you an idea of why I'm soooo worried ?

Though I will try to find your site again, is there anyway please that you could copy your answer to my email ??? PLEASE !! Thank you. Am disabled so monies are snug. Maybe a pro can help us pinpoint the issue and still keep an arm if not a leg. Thanks again. :). Steff


Continue reading at PLUMBING DRAIN NOISE REPAIR or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see CLOGGED DRAIN DIAGNOSIS & REPAIR - clogged drains may gurgle or burp

Or see PLUMBING VENT NOISE - since vent problems can cause gurgling at drain lines

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