Diagnose Clogged Drain vs Septic Backup or Failure
Blocked Drain Diagnosis for Building Owners/Managers
Blocked drain or drain backup diagnosis: caused by drain blockage versus caused by septic system failure: here we explain how to determine if a blocked or slow drain is due to a problem inside the building or outside in a sewer line or failing septic system.
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.
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DRAIN vs SEPTIC - Is the slow drain problem due to indoor plumbing or the septic system?
Is it a Plumbing Problem or a Septic System Problem - A First Look
Sewage odors, wet areas on the property, slow fixture drains, gurgling drain noises, or plumbing fixtures which
"back up" or overflow back into the building may be the first signs of trouble at a property. Image courtesy Carson Dunlop Associates.
[Click to enlarge any image]
If there are sewage odors or soggy sewage-smelling wet areas at a property, the on-site waste disposal system
is likely to be at fault. Even so, without further investigation we don't know yet if the problem is a simple
repair such as a broken pipe underground, or a costly failure such as a saturated absorption field.
If building drains are slow or clogged, the problem could be the in-building plumbing drain-waste-vent (DWV) system
or there may be a problem with the septic system. Without further investigation we don't know.
these clues (and articles about them) that assist in diagnosing clogged drains, drain backups, and septic or sewage odors:
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 sewe line is blocked or there is a failing or blocked onsite waste disposal system (septic system).
Our client (left) is pointing to a leaky clamp patch on a building drain line. Odd and excessive slope, a mix of materials, and this patch were evidence of amateur workmanship that presaged problems with this drain system.
Curtain Drain - Design Sketch for Protecting Drainfields from Wet Soils
Inspect the septic system absorption field: if the field is wet or smelly we suspect a septic absorption field failure.
If the absorption fields
are properly installed there is adequate clearance, typically 4.5 ft. between the bottom of the field and the top of the seasonal (spring)
high water table on the property.
Otherwise in wet weather conditions your field is flooded, cannot readily accept effluent from the tank,
and worse, you're also contaminating the local groundwater with pathogens from the septic tank.
If your absorption field is on a slope and is
subject to high levels of surface or subsurface runoff, you may need to install an intercept drain or curtain drain (sketch above, source US EPA) up-slope from the
Details are at FLOODED SEPTIC SYSTEMS, REPAIR.
Keep the intercept drain or curtain drain at least 10 meters from the absorption field perimeter. If the field is flooded and you do not have
problems with surface runoff, subsurface runoff, or high water table, before you assume that the field is at the end of its life, check for
constantly running plumbing fixtures such as running toilets or a water softener which is stuck in its "backwash" cycle.
If exploration of the on-site waste disposal system piping from house to tank, tank to distribution box, and
distribution box to drainfield indicates that the failure is in the drainfield (or absorption system), a more
extensive system repair is needed and significant costs are likely to be incurred.
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.
Also see SEWER GAS ODORS and Sewer Line Replacement diagnosing a clogged drain leads to drain line replacement - step by step photo-illustrated guide to drain replacement.
Continue reading at CLOGGED DRAIN DIAGNOSTIC CHART or select a topic from the More Reading links or topic ARTICLE INDEX shown below.
Or see SEPTIC BACKUP REPAIR
Suggested citation for this web page
CLOGGED DRAIN vs SEPTIC PROBLEM at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.
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- AGE of PLUMBING MATERIALS & FIXTURES
- BACKUP PREVENTION, SEPTIC
- BACKUP PREVENTION, SEWER LINE
- CHECK VALVES, WATER SUPPLY
- CHECK VALVE FAQs
- CLEANOUTS, PLUMBING DRAIN
- CLOGGED DRAIN DIAGNOSIS & REPAIR - home
- CLOGGED SUPPLY PIPES, DIAGNOSIS
- CLOGGED SUPPLY PIPES, HOT WATER
- CLOGGED SUPPLY PIPES, REPAIR
- CONDENSATE HANDLING
- CONDENSATE RETURN PIPES, PUMPS, STEAM
- CONDENSATION or SWEATING PIPES, TANKS
- COPPER PIPING in buildings
- CROSS CONNECTIONS, PLUMBING
- DIAELECTRIC PIPE FITTINGS
- DRAIN & SEWER PIPING - home
- HOT WATER IMPROVEMENTS
- HOT WATER PRESSURE IMPROVEMENT
- ISLAND SINK PLUMBING VENTS
- LEAK CAUSES in WATER PIPING
- LEAK TYPES, WATER SUPPLY or DRAIN PIPES
- LEAKY PIPE REPAIRS
- NOISE, PLUMBING SYSTEM
- ODORS, DRAIN & SEWER LINE SOURCES
- PIPING in BUILDINGS, CLOGS, LEAKS, TYPES - home
- PLUMBING NOISES
- PLUMBING VENT PIPING - home
- SEPTIC BACKUP PREVENTION
- SEPTIC BACKUP REPAIR
- SEWER GAS ODORS
- SEWER LINE LEAKS & ODORS
- SEWER LINE REPLACEMENT
- SOUND CONTROL for PLUMBING
- SUPPLY PIPING - home
- TRAPS on PLUMBING FIXTURES
- VALVES, PLUMBING
- WATER HAMMER NOISE DIAGNOSE & CURE
- WATER PIPE CLOG DIAGNOSIS
- WATER PIPING GROUND BOND
- WATER PRESSURE LOSS DIAGNOSIS & REPAIR - home
- WATER PUMPS, TANKS, TESTS, WELLS, REPAIRS - home
- WATER PUMP CONTROLS & SWITCHES
- WATER SOFTENERS & CONDITIONERS
- WATER SUPPLY - home
- WATER STAINING CONTAMINANTS
- WATER TANK: USES, TROUBLESHOOTING
- WATER TREATMENT EQUIPMENT CHOICES - home
- WELLS CISTERNS & SPRINGS
- WINTERIZE A BUILDING
- FAQs below discusses field reports of problems & solutions for this topic
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Technical Reviewers & References
Publisher's Google+ Page by Daniel Friedman
Click to Show or Hide Citations & References
- 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.
- Ten Steps to Keeping a Septic System Working, suggestions from the U.S. EPA, edits and additions by DJF
- 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.
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair