Septic dye testing is easy: put dye into a plumbing fixture drain, run water into the system, and look for break-out of dyed effluent on the ground at the test property.

But we need to know a bit more than that to perform a valid septic test.

The septic testing protocol given here is used by most home inspectors and septic test consultants.

We give 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.

Page top photo: during a septic loading and dye test performed by the author, the septic tank overflowed and ponded at the basement entry to this home.

Conduct a Septic Loading and Dye Test

Septic dye tests involve flushing a special fluorescent dye down a toilet or other drain.

The dye itself does not make anything happen. It is simply a colored indicator that can confirm that water found on the ground surface outside has come from the fixture where the dye was introduced - thus that the septic system has failed. It's the volume of water put into the septic system, combined with a competent inspection that form a valid septic test.

Starting here and followed by more-detailed procedures at the end of this article we explain just what to do before, during, and after a septic test.

We also describe how to report septic test results and we explain how to keep out of trouble such as spilling dye, leaks indoors, or damaging the septic system.

Septic system loading and dye tests are recommended for home buyers, for home owners who need to assess the condition of their septic system, and they may be required by a lender if you are buying a home.

A septic dye tests includes these three easy steps:

1. Dye: Flush a special septic dye down a toilet or other drain.
   
   How much dye, what color to use and where to put it depend on site conditions, the septic tank size, water test volume and where you can find a working toilet.
   
   Details about how much septic dye to use are at SEPTIC TEST VOLUMES & DYE AMOUNTS
2. Water: Run a quantity of water sufficient to put a working load into the septic absorption system (drainfield)
   
   How much water or how long do you run water into the septic system depend on the building size, number of bedrooms, or other standards that may apply at your location.
   
   Most experts agree that we should use 50 gallons per bedroom as a minimum; some inspectors use 75 gallons and others set a minimum test volume of 200 gallons or more even if the property only has one bedroom.
   
   See details about how much water to run and common standards
   
   at SEPTIC TEST VOLUMES & DYE AMOUNTS
3. Look outside for breakout of septic effluent: Inspect the ground outside the building in the septic drainfield area as well as everywhere else for septic dyed water (effluent).
   
   

   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.
   
   Details about how and where to look for effluent or dyed effluent appearing outdoors at the ground surface are
   
   at OUTSIDE SEPTIC DYE TEST STEPS

Septic Dye Tests Are Useful but Not Exhaustive

The three steps above are the basics of a septic loading and dye test, often referred to simply as a "septic dye test".

Even when done properly, this test can not find all possible septic system 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.

In our more-detailed articles that follow you'll see that there is more than you can do to make the septic inspection and test far more complete and more reliable.

At RECOMMENDED ARTICLES we give a series pages with step by step details to make your septic dye test proper and safe.

Watch out: Anyone inspecting septic systems must be familiar with the hazards and safety concerns discussed

at SEPTIC SYSTEM SAFETY WARNINGS

Don't Let Someone Pump the Septic Tank Before a Septic Test

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 pump outs as a cover-up of a septic problem or failure are

at WHEN NOT TO PUMP A SEPTIC TANK: warnings for home buyers about septic tank pumping.

However, after a septic loading and dye test and before completing the purchase of a property with a septic tank and absorption system, limited but important additional information regarding the condition of the system tank and also the leach field may be obtained by having a septic contractor open, clean, and inspect the septic tank itself.

Particularly in the case of older systems that have not been serviced, if the property owner will permit this step we recommend it. When the tank is pumped, ask the pumping contractor to describe the size, type, and condition of the tank and its components, and also to tell you if s/he saw any indications that the system needs repair or that the tank or leach system are at or near the end of their life.

The links given at the end of this article give more details of how to perform a detailed and thorough septic loading and dye test, including more careful procedures, observations, choosing the right test water quantity, and septic dye quantity and making inspections before, during, and after the test water is being run. We also describe how to properly report the results of a septic test.

Continue reading at SEPTIC TEST PRE-CHECKS

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

After septic tank is pumped how long do you have to wait before you can have a legal dye test preformed

If you have had your septic tank pumped out how long do you have to wait before you can have a dye test preformed so it is legal. - On 2019-07-16 by Deb -

Reply by (mod)

Thanks for the useful question, Deb.

"Legal" doesn't come into play here as there's no statute on septic dye test details.

However if someone wants to perform a septic loading and dye test of a septic system, the septic tank needs to be full - at operating level; that means that the liquid level will be up to the bottom of the tank's outlet line.

Furthermore it would be a more-realistic test if, past that "tank full" point the system has been in normal use for a week or two. That usage assures that any temporary affects of soil drying that could mask a sluggish drainfield have been passed.

The time for the septic tank to reach "full" is not a generic number like "5 days" but rather is a function of the daily wastewater into the septic system; that volume varies by number of occupants in the home and their water-using habits.

Therefore, it's better to rely on a simple inspection of the septic tank to observe its wastewater level.

A septic inspector who can safely access the tank (doing so if you don't know how can be fatal) would, before performing a septic loading and dye test

1. confirm that the septic tank is at normal in-use level

2. confirm that the home has been occupied and in normal use for a week or two since the tank was at that level
or

3. would at the very least confirm that the tank is full, conduct the loading and dye test, and issue an appropriate warning about the limitations of the test to assess the drainfield condition

Watch out: if someone pumps a septic tank right before a septic test that test is likely to be invalid and the condition of the septic system in question.

We explain that issue

at WHEN NOT TO PUMP A SEPTIC TANK

For regular septic tank maintenance

See SEPTIC TANK PUMPING SCHEDULE 

Our septic system failed a month after the dye test

We have had a dye test done and nothing came out until almost a month later.

Is it normal and is it possible that there is an issue if no results showed up in expected time frame, but something green (ish) was in the water almost a month later? - On 2018-11-15 by Ella

Reply by (mod) -

Ella

thank you for an interesting question.

I have had cases of dye showing up days after a test when there is very slow effluent movement through soil. But not a month later.

I think good first step would be to use a UV or black light in darkness to see if the greenish water that you see will fluoresce. That's a test to confirm that a fluorescent septic dye is indeed what is being detected.

 

My septic tank is leaking into the creek - or is the creek leaking into my septic tank?

I live close to a creek and I think my tank is leaking into the creek. I know where the tank is located but that is all I know about it. I have no idea if it is a septic system or if it was designed to empty into the creek. This troubles me and I would like to correct this.

I had it pumped out and 2 days later it was half full again. 500 gallon tank. Is there a dye I can put in the tank to see if it is running onto the creek.
My email is mckeepd@amplex.net. thank you

When the creek rises so does the level of my tank. - On 2018-05-19 by Paul d

Reply by (mod) - Septic tank leaking into the creek? Creek leaking into septic tank?

Paul

From what you describe you do not have a properly working septic system and indeed it's likely that

1. your septic system is flooded and has failed - and
2. the tank is discharging sewage into the creek.

Such a system would be illegal in most jurisdictions and in any event is contaminating the creek and the environment.

You would be best served first by an onsite septic engineer who could evaluate your site to give advice on just how and what form of working septic system is feasible and most-economical for your site.

Sure you could put dye into the septic system and watch for it to appear in the creek - this article series lists sources of septic dye products. But from what you've described that's not necessary - if water is leaking into your septic tank and if the tank floods when the creek floods, we already know the answer.

See FLOODED SEPTIC SYSTEMS, REPAIR -

and note my photo showing an area of septic systems located along Wappingers Creek

 

How much ground is disturbed during a septic front load test? What if the system is damaged by the test?

To do a front load test, besides the dye, which amount of the ground surrounding the site or on top of the septic system will be disturbed.

What if there is damage to the existing system while testing is being completed.? - On 2017-10-19 by Peg

Reply by (mod)

Peg: properly performed, a septic loading and dye test does not disturbe the ground and does not damage the septic system.

However it is possible that a septic loading and dye test, using a proper and reasonable volume of test water, may show up a septic failure that was not previously apparent.

If a septic loading and dye test is not properly performed, such as running far too much water into the system, the septic system could be flooded and fail, though indeed it may recover if allowed to rest.

Septic inspection report said "could not see where the septic test water emptied" = huh?

Recently purchased house. During inspection, inspectors tested septic with blue dye.

The report states they could not see where it emptied. What does that mean - On 2017-02-01 by Susi -

Reply by (mod) - septic test report limitations

Excellent question. I'm not sure what the inspector intended to say either.

It sounds to me like a disclaimer intended to mean that you should not blame the inspector if the septic system is discovered to have failed. C

ertainly it's true that the inspector cannot see underground.

But that's not the purpose of the dye test.

Ther purpose of the septic test is to see whether liquid effluent or water at the surface is coming from the septic system.

Since you paid for this test, it seems reasonable to me to require the inspector to be more clear.

Followup by Susi - Since you paid for this test, it seems reasonable to me to require the inspector to be more clear.

@Susi,
Since you paid for this test, it seems reasonable to me to require the inspector to be more clear.o make sure septic is safe? We are to take possession of the house March 3. We are concerned.

Reply by (mod) - what else to do if the septic test report is vague or confusing

Yes: contact your inspector, tell him his report was unclear, and ask what he meant. His report should plainly state whether or not there was visible evidence of a septic system failure or hazard.

Depending on what else is known about the septic system such as its type, age, and service history (when it was last pumped) you may want further steps taken but those normally can't be done before you own a property:

The tank is opened, pumped, cleaned, inspected as part of regular septic system maintenance. If I were buying new home I would want to know how often the septic tank had been pumped and when that was last done.

Watch out: If the owner doesn't know where the tank is nor anything about its pumping history I would assume that the system may be old, in questionable condition, and has not been maintained: all conditions that increase the chances of an expensive failure regardless of the results of the septic test.

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Continue reading  at SEPTIC TEST PRE-CHECKS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• HOME BUYERS GUIDE to SEPTIC SYSTEMS - what to do when buying a home with a septic tank
• HOME SELLERS GUIDE TO SEPTIC INSPECTION - what a home seller should and should not do
• SEPTIC LOADING & DYE TEST PROCEDURE - home
• SEPTIC TEST PRE-CHECKS
• OUTSIDE SEPTIC PRE-TEST INSPECTION
  • SEPTIC FAILURE EVIDENCE, VISUAL
  • LOOK FOR SEPTIC COMPONENTS
  • DIFFICULT SEPTIC SITE DESIGNS
  • RECENT SEPTIC WORK
• INSIDE SEPTIC DYE TEST STEPS
  • AVOID SEPTIC DYE POWDER CATASTROPHY
  • WATCH FOR INSIDE
• OUTSIDE SEPTIC DYE TEST STEPS
  • SEPTIC DRAINFIELD INSPECTION & TEST
  • SEPTIC FAILURE SIGNS
  • SEPTIC FAILURE SPOTS
  • SPOTTING SEPTIC DYE BREAKOUTS
• SEPTIC TEST VOLUMES & DYE AMOUNTS
• SEPTIC DYE TEST REPORT
• SEPTIC DYE TEST WARNINGS
• SEPTIC TEST FINAL OVERVIEW
• SEPTIC DYE SOURCES, SAFETY, TOXICITY, STAINING, MSDS
• SEPTIC INSPECTION & TEST LAWS & STANDARDS
• SEPTIC TANK COVERS - must be safe and secure
• WHEN NOT TO PUMP A SEPTIC TANK - do not pump the tank right before a septic test & don't test a septic if the tank was just pumped.

Suggested citation for this web page

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

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to SEPTIC SYSTEMS

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