sink drains may be a source of strange noises Plumbing Drain Noises
Diagnosis & repair of glub-glub, burbling, and other drain sounds

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Plumbing drain noise diagnosis:

This article discusses how to identify different types of plumbing drain sounds, including the cause, diagnosis, and cure of different sorts of plumbing drain noises - how to find, identify, and diagnose the source of plumbing drain, waste, and vent piping and plumbing fixture sounds.

We discuss how to add sound deadening insulation around new work or into existing plumbing pipe routes in buildings. We also cover: What causes noisy plumbing drains? How to investigate & repair plumbing drain sounds. Add sound insulation to reduce plumbing drain noise transmission in homes. Drain noise complaints due to a V200 anti-siphon valve.

That "blub blub" or "glug glug" noise you hear from a building drain might mean that there is a problem with the drain system itself, such as a partial drain blockage, a drain venting problem, a drain odor problem, or even a failing septic system.

This article also 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.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

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

Photograph of a house with missing plumbing ventsAs we explain in more detail at PLUMBING DRAIN NOISE REPAIR, we divide plumbing drain and fixture noises into two groups:

  1. Plumbing defect noises associated with plumbing system problems or defects whose identification and diagnosis is discussed here.
  2. Normal (but annoying) plumbing system noises that will be corrected by noise transmission control or sound insulation are discussed at SOUND CONTROL for PLUMBING

[Click to enlarge any image]

Article Contents

Inadequate or missing plumbing vents & noisy, gurgling, or slow plumbing drains

If a gurgling sound is heard at a sink or shower drain only when a nearby toilet is flushed, or at a sink or shower when a nearby tub is draining, we'd suspect that the building drain-vent system is inadequate.

Photograph of a multi-S-trap plumbing fiasco

This photograph shows a multiple-trap drain on a building sink - forming a double "S-trap" which lacks venting and also is very prone to clogging.

In addition to watching for eccentric home-made plumbing traps like this pair that are likely to cause bad sink, shower, or tub drainage, check for the following:

Blocked plumbing venting & gurgling or slow plumbing drains

Photograph of a plumbing vent blocked by a visiting frog

A plumbing drain line could itself blocked, as opposed to a blocked or inadequate plumbing vent line. In the case of a partially blocked plumbing drain, case all of the fixtures served by that drain line will always be slow to drain.

When weather and safe access permit going onto a roof (or using the services of a professional for that purpose), check for blocked building plumbing vents such as plumbing vents that may have become blocked by an insect nest, birds nest, or as shown in this photo, a frog.

In freezing climates, check in winter to be sure that the plumbing vents are not being blocked by frost or by snow-cover.


Gurgling drains may indicate a partially blocked or sluggish sewer piping or or blockages in the private septic system

If the outside sewer line is partially blocked, or if waste piping to a septic tank or from a septic tank to a drainfield is partially blocked, the building drains may appear to work normally until there is a surge of usage such as an increase in occupants or when using a washing machine.

In lighter usage the waste and wastewater flow down into the main drain line or sewer line where they are in effect, "stored" while the waste slowly seeps past the partial blockage. As wastewater seeps past the partial main drain blockage a gurgling sound may be produced at fixtures in the building as air is drawn intermittently into the drains - an effect more pronounced if the building drain vent system is inadequate.

In heavier usage of building fixtures, such as when there are many occupants or when doing laundry, the additional volume of water may first cause this "gurgling drain" symptom to be more pronounced, and as the blockage worsens, the building drains may actually back up during heavy use. This condition can also produce sewage smells or sewer gas backups into a building.

Gurgling drains heard indoors may also be caused by a clogged septic filter, as reader Will pointed out (at SEPTIC FILTER CLOGGING SIGNS 2017/01/14), or by clogging anywhere that blocks sewage into or out of a septic tank.

At the end of this article we list further diagnostic advice for plumbing noise diagnosis & repair, curing blocked drains, diagnosing blocked septic systems, or detecting inadequate plumbing vent systems.

Also see SEPTIC BACKUP PREVENTION (private septic systems)

or see SEWER BACKUP PREVENTION (buildings connected to municipal sewers)

and also see the health and safety concerns discussed

Sounds of running or dripping water in a building drain

Photograph of a house with missing plumbing ventsContinuous Plumbing Drain Sounds like Trickling Water or Water Dripping Noises

Trickling water sounds coming from a building drain or fixture might indicate a fixture leak problem.

A sound of dripping heard inside a drain line, or the sound of continuous running water may be heard.

Both of these can indicate that a plumbing fixture in the building has a water supply leak which is leaking into the fixture.

If the drip and sound are occurring outside of the fixture or its drain, such leaks are usually discovered pretty quickly when water or leak stains appear in the building.

But a plumbing leak that causes a toilet to run, the only clues might be noticing that the toilet fill valve is sometimes re-filling the tank even though no one has used the toilet, or one might hear water running in the building drains, or if the property is served by a private septic system, the system may experience flooding and backups.

Also see SINK LEAK DIAGNOSIS & REPAIR where we discuss repairing a leaky (and dripping) sink drain basket / strainer assembly.

Normal plumbing drain sounds

Hearing the sound of running water in a building drain is not likely to indicate a problem with the drain system itself. In older buildings where cast iron and steel drain pipes were used, not much sound normally is heard: even the sound of running water, say when a shower is running or when a toilet was flushed.

But in a more modern structure that uses plastic or copper drain piping these materials can transmit the sound of running water to the building interior. Builders can reduce sound transmission from plumbing lines by enclosing them in insulated chaseways.

We have also found cases in pipes in a building transmit sounds from one area of the building to another. We've also found that electromagnetic fields generated in a building, say by a bank of electric meters located in one area, can be transmitted to other building areas through metal piping.

Normal (but annoying) plumbing system noises that will be corrected by noise transmission control or sound insulation are discussed


a section of SOUND CONTROL in buildings where we describe controlling the transmission of plumbing noises in buildings.

How to find the source of plumbing drain sounds

An experienced plumber can often diagnose these problems quite quickly since s/he is more familiar with plumbing problems than most homeowners. But if you want to do some drain sound detective work yourself here are some steps that might help.

How to repair problems causing plumbing drain sounds

Suggestions for repairing or reducing plumbing drain noises and sounds are at   


Excerpts are below.

Reader Question: What can we do about the loud noises coming from the plumbing drains in our home?

Foam insulation in plumbing pipe chase (C) D Friedman Eric Galow

We moved into our home 6 years ago and whenever the ensuite toilet is flushed we can hear the water very loudly go down through the pipes. Recently, whenever ANY toilet is flushed or a sink drained on the 2nd floor we can hear the water travel down the pipes.

What is the cause and how can we fix it? Thank you. Kathy in Calgary

[Our photo, left, shows ABS drain/waste/vent piping (DWV Piping) in a ceiling pipe chase in a New York home during a recent building addition project, courtesy of Galow Homes.

The sound insulation steps for this plumbing drain and pipe chase are illustrated in detail at SOUND CONTROL for PLUMBING

Reply: explanation of plumbing drain noise transmission and suggestions for adding sound insulation

Kathy, I am guessing that your home is fairly new and that the drain piping is ABS plastic (or PVC plastic) run in walls or pipe chases that at least in part pass through building interior walls or ceilings.

Those pipes are indeed noisy and the noise is easily transmitted to the room interiors. By contrast, older buildings that used cast iron drain piping find there is less noise transmitted by wastewater running through the drains.

The level of noise transmitted is a combination of the acoustic transmission properties of the thinner walled plastic piping, the proximity of the piping to occupied space, the absence of noise insulation around the pipes, and details of exactly how the pipe was routed and supported.

Specifically, pipes that are in solid contact with building framing or drywall transmit more noise. Pipes that were suspended using acoustic-isolating hangers transmit less noise to the building interior.
As we cite

According to the Canadian CNRC, "Noise reductions up to about 15 dBA can be obtained relative to systems where no resilient mounts are used for pipes."

What to do now to reduce drain pipe noise?

Foam insulation in plumbing pipe chase (C) D Friedman Eric Galow

Because it would be costly to tear out ceilings and walls to mess with pipe supports and routing, I'd seriously consider blown-in insulation into the areas where these pipes are routed. Typically you'd fill the ceiling joist or wall stud bay where the pipe is contained - fill it completely, a step that significantly reduces noise transmission.

Our photo (left) shows what the ceiling pipe chase (and surrounding areas) looked like after a professional blown-in foam insulation job in the same New York home. Subsequently of course drywall was installed over these surfaces (we do not leave foam insulation exposed because of fire hazards).

After this foam was installed there was no plumbing noise detected in this area when the toilet was flushed in the floor above.

Use foam insulation because it will flow around the piping into odd-shaped spaces and will fill the pipe space completely.

Don't worry, your foam won't have to fill an entire wall or ceiling space, just the space where the pipes actually run, typically 16" or 24" wide by the length of ceiling section or height of wall section by the typical joist or stud width, say 10" or less for 2x10 ceiling joists, and 5 1/2" for 2x6 wall studs or 3.5" for 2x4 wall studs.

Nevertheless the volume of these spaces is more than you can fill consistently, adequately, and economically in a do-it-yourself project using little spray cans of foam purchased at a building supplier. So I recommend hiring a foam insulation installer.

Of course your foam installer should not have to tear off drywall nor foam as extensively as I show in our plumbing chase foam insulation photos above.

Rather it will probably be quite possible to fill the appropriate pipe routing cavities with foam by injecting foam through very small openings spaced along the route of the piping. The result will be no more than occasional 1/2" diameter or less holes to patch and paint along the pipe route.

Install Missing plumbing vents to eliminate odors, sewer gas explosion risks & unsanitary conditions

Repair frost-blocked plumbing vents

Other Plumbing System Noises

Noisy water heaters are discussed

Stop Sewer Gas or "Sulphur Smell" Odors Caused by clogged plumbing vents, drains, or septic systems

Clogged, partly clogged, slow drains or a partly-blocked, failing drainfield can also cause odors when the surge of water from the washer causes a gas backup in the system: see Diagnosing Clogged Drains for more detailed advice along that problem path.

Watch out: sewer gases contain methane and can cause destructive, even fatal explosions in buildings.

Septic additives like Rid-x won't fix a problem with building vents nor sewer odors, and are generally not recommended anyway - see Additives & Chemicals for septic system maintenance. Are septic products needed? Are septic treatments legal?

Question: noise in shower pipes when air conditioner drains into sump pump

(June 24, 2015) Kim said:
I had a new air conditioner and sump pump installed last year before I could use my air conditioner. Now this year the condensation pipe runs to the sump pump but when it comes on to drain the water the pipes in the shower makes a noise sometime. Is that normal



I might say "normal" if we mean "common" but that's not necessarily OK. I'm not sure what you're hearing. If you hear water dripping into a trap that may be fine. If you hear gurgling drains then there's a problem with a drain blockage or with inadequate drain venting.

Question: noise in pipes when we flush the toilet

(Nov 3, 2015) david said:
when we flush our toilets there is a drain noises coming form the cilling


David, in the More Reading section above these articles ought to help out:

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


Or see PLUMBING NOISE CHECKLIST our complete list of various plumbing system noises

Question: Humming sound while water is running

(Nov 9, 2015) Vic said:
I have a two story house. When I flush the toilette or run the kitchen water, I hear a humming sound that last the whole time the water is running, but when I use the water up stairs I don't hear any sound. What could it be?


I don't know; if you have a private well I suspect well or pump noise transmission, say of a vibrating pump motor or loosely-mounted waer pipes.

If you're on municipal water I'd be looking for a valve that's obstructing the water and affecting the velocity just to create a noise to annoy you. Try slightly closing a supply valve.


Continue reading at PLUMBING DRAIN NOISE REPAIR - how to fix drain noises, 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

Or see this

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