InspectAPedia ^TM

Plumbing Drain Noises - Diagnosis & Repair Enter your search terms Submit search form   Search This Website - InspectAPedia.com Plumbing drain sounds may explain drain problems What causes noisy plumbing drains? How to investigate plumbing drain sounds How to repair problems causing plumbing drain sounds This article discusses the cause, diagnosis, and cure of plumbing drain noises. 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. Here we discuss the causes and cures for plumbing drain noises, and we refer to key companion articles that assist in that diagnosis. Citation of this article by reference to this website and brief quotation for the sole purpose of review are permitted. Use of this information at other websites, in books or pamphlets for sale is reserved to the author. Technical reviewers are welcome and are listed at "References." This is a chapter of Inspecting, Testing, & Maintaining Residential Septic Systems an online book on septic systems. © Copyright 2008 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use the links at page left to navigate this document or to go to Other Website Topics. Green links at left show where you are in our document & website.

Plumbing drain sounds may explain drain problems

Sounds of gurgling in a building drain

Gurgling or "glub glub" sounds in building drains are usually heard at or near an individual plumbing fixture such as a sink or shower.

Gurgling drains may indicate inadequate plumbing vents

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.

Examples of inadequate plumbing venting include

Gurgling drains may indicate blocked plumbing venting

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. See Cold Weather Septic Odors or Sewage Odor Diagnosis.

Gurgling drains may indicate a partially blocked or sluggish 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.

At More Information our articles offer further diagnostic advice for blocked drains, blocked septic systems, or inadequate plumbing vent systems.

Sounds of running water in a building drain

Continuous plumbing drain sounds like trickling water

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 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.

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.

How to investigate 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.

• Identify the fixture: Identify which fixtures are producing the sound: is it all fixtures in the building? If so we suspect a system drain problem or that the building has only a single inadequate vent system or no venting at all. If the sound occurs only at a specific fixture, we suspect a blockage or vent problem local to that bath, kitchen, or laundry area and its vent or drain piping.
• Flush the toilets: Blocked or inadequate vents can produce slow drains as well as noise. But if none of the drains are slow, but you hear gurgling at a nearby sink when the toilet is flushed, take a look underneath the sink. If the trap is shaped like an "S" over on its side, the sink is probably not vented and the flushing toilet is trying to draw air into the drain line from the nearby sink when the toilet is flushed. If the trap is shaped like a "P" over on its side, with its horizontal outlet running into the wall, we can't see if the sink is really vented or not, but the style of plumbing is more modern and it might be vented. If the trap is some crazy combination of multiple bends and parts, call a professional plumber to unsnarl the installation since such jury-rigged plumbing traps are likely to be problematic.
• Look in the attic for a plumbing drain line that passes vertically up from the floors below and out through the roof. If you can't find one, the building may not have proper plumbing vents.
• Look outside for plumbing vent pipes poking up through the roof in one or more areas. If you see a plumbing vent at one far end of the building where baths are located, but no plumbing vent stack pipe over the end of the building where a kitchen or laundry are located, those rooms may have been built without proper plumbing venting.
• Check out the septic system: for signs of backup, blockage, or odors outside. Effluent breaking out to the surface, muddy or soggy areas, smelly areas, may indicate that the septic system, or part of it, are failing and are periodically not accepting waste.
• Call a plumber to investigate further.

How to repair problems causing plumbing drain sounds

Repairing Missing plumbing vents

Repairing frost-blocked plumbing vents

• Fixing a freezing plumbing vent line in which the plumbing vent becomes partially or fully blocked by frost or ice where it extends above the roof in a freezing climate, probably requires the installation of a larger diameter vent from the attic out through the roof.
• First check for leaks: before installing a larger diameter plumbing vent line, make sure that there is not a hot water leak into the plumbing drains or continuous shower use. A water leak into the drain system can result in continuous movement of water vapor or "steam" upwards in the vent system too. In freezing weather that water vapor may condense and then freeze in the outdoor portion of the plumbing vent system simply because it's passing that way continuously.
• Too-short plumbing vent stacks: A plumbing vent stack which is too short above the building roof can be blocked by snow and then stop venting. But that does not mean that we should be installing very tall (3' to 6') plumbing vents. Except in areas of unusual snow depth such heights are probably much higher than needed. The plumbing vent stack above a roof needs to be high enough to never be covered by snow, not more. I speculate (really am guessing) that perhaps if a vent is TOO tall in a cold climate, moist air never will escape at its top because the added cold length of pipe actually encourages freezing.

Odors and 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.

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?

We've posted articles on diagnosing odors at:
Sewage Odors in Wet or Cold Weather - Septic Odors or Sewage Odor Diagnosis & Repair Guide for diagnosing and eliminating cold weather sewer gas odors, and
Sewer Gas Odors diagnosing, finding, and curing septic tank and sewer line smells. I welcome questions or content suggestions for these topics.

Technical Reviewers

Particular thanks are due to experts and also consumers who read these articles and suggest corrections, changes, and additions to the material.

• Daniel Friedman - principal author
• Technical reviewers are invited to comment or ask questions - contact us

More expert information on this topic

More Information on Septic System Diagnosis, Maintenance, & Repair

• Backups and Clogged Drains diagnosing septic backups and septic system failures versus clogged drains - key step in septic repair
• Sewage Odors in Wet or Cold Weather - Septic Odors or Sewage Odor Diagnosis & Repair Guide for diagnosing and eliminating cold weather sewer gas odors
• Sewer Gas Odors diagnosing, finding, and curing septic tank and sewer line smells
• Sewer Gas - Methane and other septic system gas explosion or asphyxiation hazards such as hydrogen sulfide


• The Septic System Information Website home page for this topic
• Septic Systems Inspection, Testing, & Maintenance- online textbook. Detailed how to inspect, maintain, repair information
• The Home Buyer's Guide to Septic Systems
• Ten Steps to Keeping a Septic System Working, suggestions from the U.S. EPA, edits and additions by DJF
• What is a Septic System An Engineer's View & Septic System FAQ's


Pennsylvania State Fact Sheets relating to domestic wastewater treatment systems include

• Pennsylvania State Wastewater Treatment Fact Sheet SW-161, Septic System Failure: Diagnosis and Treatment
• Pennsylvania State Wastewater Treatment Fact Sheet SW-162, The Soil Media and the Percolation Test
• Pennsylvania State Wastewater Treatment Fact Sheet SW-l64, Mound Systems for Wastewater Treatment
• Pennsylvania State Wastewater Treatment Fact Sheet SW-165, Septic Tank-Soil Absorption Systems
• Document Sources used for this web page include but are not limited to: Agricultural Fact Sheet #SW-161 "Septic Tank Pumping," by Paul D. Robillard and Kelli S. Martin. Penn State College of Agriculture - Cooperative Extension, edited and annotated by Dan Friedman (Thanks: to Bob Mackey for proofreading the original source material.)

InspectAPedia ^TM Home & Site Map - Building Inspection, Diagnosis, & Repair, Environmental Inspection & Testing - Research Website

Home Inspection Construction Consulting Services & advice for home buyers

Contact Daniel Friedman for website content suggestions or for fee-paid consulting

	Enter your search termsSubmit search form
	Search This Website - InspectAPedia.com