septic dye breakout at a basement entry from a failed septic system buried below a driveway during conduct of a septic loading and dye test
- an expert can find clues and perform tests that reduce risk of a costly surprise Warnings When Performing a Septic Loading & Dye Test

Septic testing troubles and mistakes:

This article provides warnings and pitfalls facing people performing a Septic Loading and Dye Test.

We list a number of mistakes that the test consultant might make, resulting in septic system damage, dye spills, invalid septic test conclusions and other dangerous or costly errors.

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DYE TEST WARNINGS - Septic Inspection & Loading/Dye Test Warnings

Although septic system inspection & testing can often find a costly failure, unsafe conditions, or other improprieties, the procedures cannot find all possible septic system problems. So by itself, that is without an expert visual inspection and possibly further investigation at the septic tank, D-box, and even the drainfields, a dye test is not indicative of complete condition of the system.

On the other hand, experienced inspectors have found found so many failed septic systems with this septic loading and dye test procedure that it's well worth performing and it offers an inexpensive way to detect many expensive problems.

  • Watch out: Septic Inspection Safety: Review Safety Warnings to Septic System Inspectors in our main text: "Inspecting, Testing, & Maintaining Residential Septic Systems.

  • Weak Septic Dye or Inadequate Amount: Some septic dye tablets, such as "Trace-A-Leak Tablets" may have limited capacity. These tablets are used by some inspectors for septic loading & dye tests. However it is unlikely that they are a reliable indicator of surface breakout or seepage.

    While individual tablets will dissolve in 1-3 minutes, they produce a yellow-green dye which may be difficult to see in grassy areas. Worse, individual tablets produce dye in concentrations of 1 ppm/50 gallons of water. In order to stain a 1000-gallon septic tank to produce visible output in the fields, at least 200 such tablets would be required. Tablets are packaged in bottles of 100. A few tablets, therefore, would in my opinion produce an unreliable test.
Where the septic dye was placed shows the problem (C) Daniel Friedman
  • Watch out: Wrong septic dye insertion location or wrong water loading location: at SEPTIC FAILURE LAWSUIT we describe an unfortunate case of a buidling inspector who was sued for performing an incompetent septic loading and dye test.

    The inspector used an inadequate amount of septic dye to possibly show up a septic system failure should effluent breakout occur, and worse, he ran water in a washing machine drain standpipe (photo at left) that drained into a separate drywell rather than into the septic system.

    The morning after the new owners moved into the recently-inspected and tested home, sewage effluent was flowing across the property.

    Even a casual inspection of the visible plumbing pipes in the building made obvious that the septic test water was not likely to be entering the main building drain. The inspector lost the case not because it was certain that a proper test would have disclosed a failed septic system, but rather because the test was so incompetently performed that the test had no chance whatsoever of finding a failed septic system.

    The home buyer didn't expect a guarantee that a failed septic system would be found, but he had been hoping for a chance at that discovery.

  • Beware of Bleach: we've encountered a number of instances in which the seller or real estate agent was attempting to assure a satisfactory water coliform test by shocking the well just before a home inspection - in some cases just minutes before arrival of the inspector.

    Not only is such an act likely to be a commission of actionable fraud, but it may do more than "hide" a well sanitation issue. If a large amount of bleach has been placed into the septic tank it is possible for dye entering the system to be bleached colorless. If there is ready access to the septic tank entry port, observe the septic dye entering the tank and confirm that it's not becoming colorless at the instant of entry there.

    A simple HACH test can also check for the presence of bleach in the water supply or in suspected bleached-effluent. This problem is discussed in more detail at CHEATING ON WATER TESTS - Water Test & Septic Test Cheating Warnings for Home Buyers and Home Inspectors. Four grams of 12% bleach will remove the coloration of one gram of septic dye in solution according to Tramfloc Inc.

  • Flush the toilet once BEFORE you put in the dye: this dye stains carpeting and hands; if you put in the dye and the toilet overflows rather than draining it's a terrible mess.

    Watch out: See AVOID SEPTIC DYE POWDER CATASTROPHY and don't spill dye powder nor dyed water in the building.

  • Certification: WARNING: in some jurisdictions, there are existing septic system inspection procedures and in some cases inspector training/certification are required. In some jurisdictions the inspection procedure does *NOT* include the introduction of dye nor system loading with extra water volume.

  • Cesspools can obscure or prevent effective septic loading and dye testing:: If a cesspool is in use at a property a septic dye test would not be a reliable indication of good system condition since the test could simply be trying to fill a large near-empty hole in the ground; yet such a system may fail soon after being returned to active or heavier regular use.

    : watch out for cave-ins, keep away: cesspools, particularly older site-built cesspools present a very high risk of collapse from an unsafe cover or following some types of service involving pumping, aeration, or hydro-jetting.

    Adults or children should not walk over or even near cesspools because of the risk of falling-in followed by collapse, a virtually certain cause of death. If the presence of a cesspool is known or suspected at a property its location should be roped off to prevent access and it should be investigated by a professional.

  • Drywells can obscure or prevent effective septic loading and dye testing: If a drywell system is installed, running water at the fixtures draining into this system (as may be done by some septic tests) are likely to fail to perform a loading test on the septic system even if such a test was attempted.

    First, the fixtures where water was run in attempt to test the septic system (tank and leach field) may not even be delivering water to those components if instead the fixtures drain to a separate drywell.

    It is critical to trace building drains as part of a septic test or to otherwise try to determine if the test water is actually entering the septic system.

  • Failed Septic System - Additional Warnings: The onsite waste disposal system at a property with a failing or failed system is unsanitary and risks contamination of local ground water or wells. According to the United States Environmental Protection Agency, failed septic systems are the most frequently reported cause of groundwater contamination. Once a septic system stops treating the raw sewage it not only begins to contaminate the groundwater supplies, it also begins to contaminate the surrounding soil as well.

  • High groundwater or deep septic effluent release: Systems which release septage effluent at deeper levels in the soil (below 24"), such as cesspools and seepage pits, may successfully "dispose" of the effluent (in that it is not visible to the property occupants) but are unlikely to successfully "treat" the effluent to make it sanitary.

    While such systems may appear to be "working" and may remain unregulated by local health officials, they are likely to be contaminating nearby ground water, streams, and possibly the drinking water supply.

  • Mound Systems and Dosing Systems WARNING: mound system using a pumping station are often designed to use pressure dosing, pumping water to the mound at intervals, usually once per day.

    Timed application of septic effluent & dye allows the mound to rest and prevents unnecessary clogging in the distribution system by maintaining aerobic conditions. Overloading of these systems during testing could damage the septic system.

    • Maximum sewage loading rate to trench and bed in gallons per square foot per day varies depending on soil percolation rate but ranges from .025 to 1.75 GPFD, with the lower numbers for beds than for trenches. (Ref. 14.)
    • Pumping tank working capacity is (typically) 25% of the daily sewage volume; actual tank capacity should be much larger than this, at least one day's sewage volume.
    • Vehicle traffic: Driving heavy vehicles over the mound can damage or destroy it. Typical mound life is 20 years.
    • During testing watch closely for seepage at the perimeter or "toe" of the mound.
    • We recommend limiting the test volume on mound systems to the pumping tank working capacity. This might be as small as 125-150 gallons.
    • Trees and stumps may have been disposed-of below the area to be filled as a septic mound. This "disposal" helps the builder by adding volume and saving on trucked-in fill to form the absorption system. If you see tree trunks extending out from the base of a septic mound this condition is likely - and improper.

  • Pumping a Septic Tank Before Testing: Do not permit the septic tank to be pumped before the septic loading and dye test - that will prevent a valid test of the system and in particular, prevents loading of the drainfield. More details about the problem of septic tank pumpouts as a cover-up of a septic problem or failure are at Don't Pump Before Testing Septic Systems: warnings for home buyers about septic tank pumping.

  • Replaced Septic Tanks: When a septic tank has been replaced but connected to an older existing leach field there is increased risk that problems with the previous (failed) tank may have pushed solid waste into the leach field before the tank problem was discovered.

    If this is the case, which would be common, one should expect that even if the leach field did not fail during a loading and dye test, its future life will be more limited than otherwise.

  • Steel septic tank warnings: older septic systems often used steel tanks which eventually rust out and have to be replaced. A damaged tank can also result in costly damage to the leach field or seepage pits. Opinions of steel tank life range from 15-30 years. If a property is served by an old steel tank it could require replacement at any time.

    SAFETY: Child or Adult Safety Hazard: If an older steel tank (or a home-made system) is found or suspected to be present the owner should immediately protect the area over the tank from access: rotted or rusted covers can collapse and a child or adult can fall into the tank - an event which can be fatal. Also, watch for and investigate any areas of soil subsidence quickly.

  • Other Septic Dye Test Limitations: Dye can identify certain kinds of septic failures, but not others. By itself a dye test is not indicative of overall condition of the system. The probable locations of tank and absorption system are inspected before, during, and after a loading or dye test if these were ordered.

    Ground conditions such as snow, ice, leaf cover, can make it impossible for the inspector to see dye-colored water even if it is leaking to the surface. Reasonable care was used in determining the location of the components.

    However because these components are buried, no guarantee can be made regarding the location nor condition of private waste system components unless specific additional tests, involving opening tank, pumping, and possibly excavation, are ordered. These tests are not usually part of a home inspection unless preliminary examination shows an apparent problem.

These pages are part of our SEPTIC DYE TEST PROCEDURE for testing septic system function. Technical review by industry experts has been performed and is ongoing - reviewers are listed at REFERENCES. Comments and suggestions for content are welcome.


Continue reading at SEPTIC TEST FINAL OVERVIEW or select a topic from the More Reading links or topic ARTICLE INDEX shown below.


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SEPTIC DYE TEST WARNINGS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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