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 surpriseStep by Step: How to Perform a Septic Loading & Dye Test

  • STEP BY STEP SEPTIC DYE TEST - CONTENTS: How to perform a septic loading & dye test, step by step. What to do before, during, and after the test; How much septic dye to use; How to report septic test results; Septic Test warnings and pitfalls
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Steps in a septic loading & dye test: beginning here, this article series provides details of the Septic Loading and Dye Test procedure for testing the function of septic systems, focused on condition of the effluent disposal section, also known as a leach field, seepage pits, drainfield or drainage field.

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HOW TO PERFORM a SEPTIC DYE TEST - How to Properly Conduct a Septic Loading and Dye Test

septic dye going down a toilet

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Septic System Loading and Dye Tests often requested by certain lenders, involve flushing a special dye down a toilet or other drain combined with a known quantity of water sufficient to put a working load on the absorption system.

If waste water leaks to the ground surface (an unsanitary condition indicating serious septic failure) one may find dye in that water provided the septic system is flowing at common rates. Dyed effluent usually appears in 20-30 minutes on a failed system but can take up to five days to show up. If at a building inspection suspect wet areas are observed I recommend a dye test even if one was not previously requested.

When wet areas are not found (or created by running water into the septic system) on the property being inspected, dye tests may still be performed to meet requirements of some lenders.

Although this test can often find a costly failure it does not find all possible problems. So by itself a dye test is not indicative of complete condition of the system. On the other hand, I've found so many failed systems with this procedure that it's well worth performing.

Why do We use Septic Dye during a Septic System Test?

Septic dye tests involve flushing a special florescent dye down a toilet or other drain. The dye itself does not make anything happen.

Septic dye stains the test water: the septic dye is simply a colored indicator that can identify water found outside as having come from the fixture where the dye was introduced. If we did not use any tracer dye we could still conduct a septic system loading test. But if the test produces a sewage effluent breakout anywhere on or near the test site, the inspector could be subjected to an argument that the liquid seen outside did not come from the tested property's septic system.

Now a careful pre-test inspection can avoid most such problems by making note of the pre-test conditions, including any exisiting wet or smelly areas, and including noting the absence of such areas.

A pre-existing wet area might already indicate an ongoing septic system failure, or it might be due to other problems such as uncontrolled surface runoff or local ground water. Septic dye can often (not absolutely always) help sort out those differences.

Watch out: if somone is trying to fool the septic inspector s/he might have poured bleach into the water supply or even directly into at toilet or septic tank before the test begins. Bleach, and on occasion other site conditions, can "hide" the dye itself even though the septic test produces an effluent breakout. Some methods to detect this sort of mistake (or on occasion deliberate dishonesty) are described at CHEATING ON WATER TESTS.

It's the volume of water introduced into the system that forms the actual "test". If waste water is coming to the surface (an unsanitary condition indicating serious septic failure) one may see dye in that water, provided the septic system is flowing at common rates.

When suspect wet areas are observed, if the system has no maintenance history, if the area is known to have problem soils, or if other historic or site conditions raise question about the condition of the system we recommend that the inspector perform a dye test.

A septic loading and dye test will by no means find every septic failure, but this methods finds many failures that otherwise are unnoticed by a home buyer until shortly after moving-in. Septic loading and dye tests are complimentary to and should precede any further inspection steps taken such as pumping the septic tank.

Septic System Testing Articles


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