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How to fix a blocked or clogged drain:
This article series explains how to troubleshoot & repair slow or blocked plumbing drains, diagnose & fix sewer line or septic system backups & how to distinguish between a probable septic system failure versus a probable blocked building drain or sewer line.
. What signs indicate a clogged drain? How do we distinguish between a clogged drain and plumbing vent troubles? What are the steps in fixing a clogged drain?
When a building drain or main sewer line is clogged or slow, or when there is a septic system backup, it's important
to determine where the problem lies, since the repair steps can be quite different and costs can vary widely.
Here in addition to a text-based explanation of how we diagnose blocked drains or related sewer line or septic system problems, we include in a drain & drainfield diagnostic table.
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.
Clogged Drain Diagnosis & Repair: how to fix slow or clogged plumbing drains
[Click to enlarge any image]
FIRST SIGNS - What are the First Signs of Trouble Indicating Failure of a Septic System?
What should a building owner do if the building drains stop working or there are odors or sewage-suspect wet areas on
It is important to distinguish between a simple blocked trap or blocked pipe and a failing septic system.
That's because the remedies, as well as the costs, are quite different.
The photo at page top shows the final repair for a toilet that was backing up - in this case the drain was blocked by
a child's underpants.
See TOILET REPAIR GUIDE.
By following the investigative steps we recommend you can determine the difference between
a blocked drain and other more extensive plumbing or septic system problems.
Our photo just above shows a clogged shower drain in an older home.
That white blob of crud in the drain trap may be removed or pushed through by a plumbing snake. But if the building is served by galvanized drain lines, those may be blocked internally by rust or mineral deposits, leading to a more costly repair.
Is it a Plumbing Problem or a Septic System Problem - A First Look
A simple initial step
must be taken to distinguish between an in-building plumbing problem and an (outside) on-site waste disposal
Simply put, if a single building fixture is sluggish or clogged, but if other building fixtures
drain properly, you should suspect a local clog or vent problem at the individual fixture.
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 onsite waste disposal system.
Details to help you make sure that you know whether the clogged or slow drains or backed up drains are due to a drain blockage rather than due to a failing septic system are provided
at CLOGGED DRAIN vs SEPTIC PROBLEM
Diagnose Slow or Clogged Drains: 12 step procedure to diagnose & fix a blocked or slow plumbing drain
Here are twelve easy steps to take, in order, to deal with a clogged or slow drain. In the process we'll discover
if the problem is only a blocked pipe or if the septic system is at fault. Before digging up the septic
system be sure to go through these steps - it may save you some money.
Note: Some of these plumbing drain clog diagnostic steps attend to distinguishing between a drain problem and a septic system problem.
If your building is connected to a sewer system rather than a private septic system, the text in these steps that identifies the location of a problem in drain lines outside the building still apply, as your building sewer line connection between building and sewer main may be in trouble.
Of course other features, such as a flooded or failed septic drainfield won't pertain directly, though indeed a municipal sewer can also back up into a building.
Check several building plumbing fixtures: Refining the above procedure,
if the main building drain is clogged, or if the on-site waste disposal system
is blocked, fixtures on upper floors in a building may appear to drain normally, while fixtures on lower floors
or at the lowest level in the building may not drain at all, or may even overflow back into the building when upper
floor fixtures are operated.
If the problem is just at a toilet see TOILET REPAIR GUIDE for how to diagnose and repair toilet flush, fill, noise, drain, odor, sound, running problems of all kinds.
Check the history of the slow drain problem: if the drain has always been slow, we suspect a plumbing problem such as improper venting, a drain installation error, or a problem with the individual fixture since the day it was installed (such as a poor flushing toilet).
If the drain used to work but has become slow, we suspect a plumbing drain/waste/vent system blockage has developed, or if the building is connected to a private septic system, that could be failing or blocked.
How to Try to clear A Blocked Plumbing Drain by Yourself
There are some simple do-it-yourself drain clearing steps that you may want to try before going further in your investigation or hiring of an expert. The four drain clearing methods listed below are discussed in detail at BLOCKED DRAIN REPAIR METHODS.
Clear a blocked sink trap: before messing with snakes, wires, plungers, and plumbers, if the blockage is at a single sink or tub trap look into the trap with a flashlight.
Use a toilet plunger to clear a simple blocked drain.
Call a professional plumber to clean individual fixture drain:
A reasonable approach at this point is to call a plumber specializing in drain cleaning.
By opening and
attempting to clean the building drain or fixture drains, an experienced plumber can determine if the problem
is with the building DWV system (drain waste vent) or if it's an outside problem. But before calling the plumber here are the simple do it yourself basics for clearing a clogged building drain. If these work you may be back in business.
If the drain clearing effort is unsuccessful, you will have paid the plumber for his/her time and also you should ask for that expert's diagnostic assistance. If the drain problem is more than a simple intermittent blockage, what is the problem?
Check the building drain-vent system: if there is not an obvious drain blockage, and if drains are slow, particularly if you hear a
"gurgling" sound at fixtures during draining, I'd suspect that the building vent system is incomplete, improperly installed, or has become
blocked (perhaps by an animal or an insect nest, or in northern climates, by snow if the above-roof extension is too short, or
by ice if the vent is too small in diameter - rising steam condenses and freezes in the outside portion of the vent).
drain problems occur only in freezing weather or when there is heavy snow, I'd suspect these latter defects.
If you hear a gurgling
at the sink when the toilet is flushed this might be the case. Have a plumber inspect and test the vent system. Blocked vents do not
usually cause drain backup but they will cause slow draining.
PLUMBING DRAIN NOISE DIAGNOSIS: since plumbing drain noises may indicate defective or clogged plumbing: how to diagnose and cure drain sounds, and
If the in-building DWV piping is not blocked, and if the drain line between the building and septic tank (or equivalent
component such as a cesspool) is not blocked, and if in-building drains are slow or blocked, the problem is most-likely in
the on-site waste disposal system.
Even if the problem appears to be "outside" of the building, you still have not determined whether the problem there
is a blocked or damaged drain line or a more extensive failure of the onsite waste disposal system.
This is a very
important distinction. Un-clogging a drain line, or excavating and repairing a crushed or broken drain line outside
the building is typically a much less costly repair than replacement of a septic tank, drain field, or seepage system.
If the problem is in the on-site waste disposal system, additional inspection and testing are needed to
determine the nature of the failure.
Again, a blocked drain line exiting a septic tank, or a failure in the
distribution box (connecting the septic tank to the network of drainfield lines, seepage pits or galleys) the
repair needed may be local and modest in expense.
Snake (clean) the building drain between house and septic tank: this will check for obstructions, roots, and collapse
in the line between house and tank
and will also, if you don't already know, determine the probable distance from the house to the septic tank.
If you're seeing recurrent
blockages in a buried waste line, I'd suspect that it may be improperly sloped, or that the pipe may have been partly broken by vehicle
traffic, or that it's partly blocked by a tree root or debris.
An experienced drain cleaning professional can often tell by the "feel" of
the plumbing snake just what kind of obstruction has been encountered.
Open and inspect the septic tank: if the intake or outlet drains from the tank are blocked because of floating scum or high sludge
in the tank, the tank needs to be cleaned. Call a septic tank pumping company.
But beware: if scum or sludge levels in the tank were excessive,
you've been pushing solids into the absorption system and you may have reduced the remaining life of that component. If the baffles are
damaged they should be replaced.
If your building is connected to a municipal sewer (not to a private septic system) there may be a blockage in or damage to the sewer line between your building and the sewer main. You might also check with your local water and sewer municipal department to be sure that there is not a temporary stoppage in the main sewer.
The sewer line between an private building and the public sewer main is the responsibility of the property owner to maintain and repair, but you may need permission from your municipality before you can excavate or make other repairs.
Find and inspect the distribution box: if the tank is clear and its inlet and outlet not blocked, and if drains are backing up in the house I'd expect the
liquid level in the tank to be abnormally high and I'd be looking for a blockage in the absorption system, or a soil absorption system failure.
The distribution box (or boxes) connect the tank outlet to multiple leach lines, seepage pits, or other soil absorption system(s) (if more than
one is present). Look in the D-box. If the box has been flooding and all of the outlets from it are equally distributing effluent, the absorption system is blocked
or in failure.
But if the box is tipped or otherwise misadjusted so that effluent is not being distributed evenly across the absorption
system sub components, that defect should be corrected. However I would not expect a tipped D-box to lead to drain backup in the building.
Also see CAMPING & EMERGENCY TOILETS and also see TOILET ALTERNATIVES for a discussion of camping toilets, chemical toilets, emergency-use toilets, waterless toilets, graywater systems, composting toilets, home health care toilets, incinerating toilets, outhouses, and latrines.
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Recent questions & answers about diagnosis & repair of clogged or slow plum bing drains, posted originally here are now found at CLOGGED DRAIN DIAGNOSTIC FAQs
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Septic Tank/Soil-Absorption Systems: How to Operate & Maintain [ copy on file as /septic/Septic_Operation_USDA.pdf ] - , Equipment Tips, U.S. Department of Agriculture, 8271 1302, 7100 Engineering, 2300 Recreation, September 1982, web search 08/28/2010, original source: http://www.fs.fed.us/t-d/pubs/pdfimage/82711302.pdf.
Operation & Maintenance Manual for Septic Tank Drainfield Sewer Systems, Missoula MT: NOrthern Region, Environmental Health Engineering, Forest Service, U.S. Department of Agriculture, August 1981. Cited by the above reference.
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.)
Builder's Guide to Wells and Septic Systems, Woodson, R. Dodge: $ 24.95; MCGRAW HILL B; TP;
Quoting from Amazon's description: For the homebuilder, one mistake in estimating or installing wells and septic systems can cost thousands of dollars. This comprehensive guide filled with case studies can prevent that. Master plumber R. Dodge Woodson packs this reader-friendly guide with guidance and information, including details on new techniques and materials that can economize and expedite jobs and advice on how to avoid mistakes in both estimating and construction. Chapters cover virtually every aspect of wells and septic systems, including on-site evaluations; site limitations; bidding; soil studies, septic designs, and code-related issues; drilled and dug wells, gravel and pipe, chamber-type, and gravity septic systems; pump stations; common problems with well installation; and remedies for poor septic situations. Woodson also discusses ways to increase profits by avoiding cost overruns.
Country Plumbing: Living with a Septic System, Hartigan, Gerry: $ 9.95; ALAN C HOOD & TP;
Quoting an Amazon reviewer's comment, with which we agree--DF:This book is informative as far as it goes and might be most useful for someone with an older system. But it was written in the early 1980s. A lot has changed since then. In particular, the book doesn't cover any of the newer systems that are used more and more nowadays in some parts of the country -- sand mounds, aeration systems, lagoons, etc.
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The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
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