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 Septic Dye Testing

   Septic Dye Testing is a non-invasive procedure that is sometimes used to determine the condition of the components of a home's waste system. A septic dye test can expose obvious leaks and inadequacies in the system and indicate the need for repairs or alterations. It involves the introduction of a fluorescent dye into the septic system, which is "traced" to ascertain that the septic system can handle the volume of waste that is currently being put through it. This test is usually performed by a home inspector or a member of a local or state health department.
   The septic dye test is sometimes REQUIRED as part of a Septic Certification by a lending institution before financing can be obtained from them for a home purchase.  
   This article will provide a brief overview of the septic dye testing procedure, it's benefits and limitations, and how it may affect your home inspection and home purchasing experience.

Different Types of Septic Inspections

   A septic dye test is considered to be part of a Routine Maintenance Inspection of the septic system. The procedures are non-invasive, require no excavation,  and are generally limited to what can be viewed above the ground surface. It is intended as an observation of the parts of the typical waste-handling system - the septic tank, distribution boxes, leach field, and any related portions of the home's plumbing and water fixtures. This type of septic inspection is performed by a home inspector, and in most cases will satisfy any requirements set forth by lenders as related to financing.

   A Functional Maintenance Inspection is performed by a septic contractor. This type of inspection is generally more invasive, and may involve the use of specialized tools and equipment to determine the actual FUNCTIONALITY of the septic system. It can help pinpoint any defects in the system and determine whether or not the system is functioning as it should.
   The Functional Maintenance Inspection is not normally required by a lender, except in cases where a home inspector or health official has noted an obvious defect or inadequacy in the home's septic system or related components.

   Both types of inspections may be ordered at the buyer's discretion regardless of lender requirements. The Functional Maintenance Inspection (by a contractor) may help to determine the need for future repairs or upgrades to the septic system which could affect the real estate transaction.

How a Typical Septic System Works

    This article addresses the typical septic system of a home, and does not address non-typical systems such as seepage pits and cess pools.
   Most septic systems that were installed following modern code guidelines are an anaerobic system. This means that waste broken down in the system without the introduction of an auxilliary source of air.
   Waste is carried from the home to the septic tank by means of a pipe (usually 3" or larger) where bacteria break down the waste.  Baffles in the tank prevent solid waste from exiting the tank. Solid waste is broken down by bacteria into a liquid form, which floats to the surface of the septic tank. The liquid exits the tank via the tank outlet, where it is directed to a distribution box (or boxes) and introduced into the leach lines.
   Leach lines are lengths of piping, usually made of perforated PVC, which carry the liquid waste and deposit it into the absorption field. The absorption field is the area surrounding the leach lines, and it is designed to distribute the liquid waste over a wide area where it can safely diffuse into the ground. During installation, the area beneath the leach lines is excavated to a depth of 18" (generally) and the trenches are filled with porous gravel or aggregate, upon which the leach lines are laid. The gravel or aggregate helps to create a reservoir for the liquid waste and prevents the leach lines from becoming clogged with dirt and clay. Absorption fields are also designed to allow some of the liquids to migrate to the ground surface where evaporation can eliminate some of the moisture.    

How a Septic Dye Test is Performed

    The septic dye test uses a fluorescent dye solution to visually identify a problem with the septic system. The dye is flushed down a toilet that is (presumably) connected to the septic system being tested. The amount of dye used is determined by the size of the septic tank. Tank sizes range from 500 gallons to several thousand gallons, and of course a larger septic tank will require that more dye be used. In most cases, several ounces of concentrated dye solution is adequate for a test.
    Then water is run into the system with a faucet (also presumably connected to the septic system) in order to flush the dye into the septic tank, and then into the absorption (leach) field. Again, the volume of water introduced to the system is determined by the size of the tank serving the septic system. The objective is to flood the absorption area with water containing the dye solution. A home inspector will use a formula which takes into account the size of the tank and the length of the absorption field to determine how much water to run into the system.

NOTE: the home inspector makes this determination based upon the information that is available to him. More on this later.

   When the system is inundated with water, the absorption field becomes saturated to capacity with dyed water. If there is a perforated leach pipe that is broken, crushed or disconnected, the dye solution will migrate to the ground surface at this point because it's progress through the leach field has been terminated. Dye may also come to the surface in several other areas such as the tank inlet and any inlets or outlets to distribution boxes connected to the system.
   In most cases, the dye will be visible on the ground surface within several hours of the start of the test. However, it may take longer for the dye to make it's way to the surface - sometimes as long as 3 days.
   It is generally up to the inspector or health department official as to how long the area will be monitored for a problem as indicated by the dye solution. Some are satisfied that the septic system is in good condition after 3 hours, and some may insist upon returning for several days after the start of the test to look for signs of dye on the surface.
   Under no circumstances should a Septic Certification be issued in less than 3 hours after the start of the septic dye test, since anything less would certainly compromise the integrity of the test.  
   If dye is observed on the ground surface, the home inspector or health department official will note this in the septic certification report, and may recommend a more thorough, invasive inspection by a septic contractor to determine the extent of the problem.    

Limitations of Septic Dye Testing

   Since this type of septic inspection is a VISUAL inspection, it has many limitations. A home inspector or health department official can only report upon what is observed above-ground, which does not always give an accurate evaluation of the health of a septic system. Some home inspectors will not perform a septic dye test due to these limitations, because so many factors can influence the results.
   One of the biggest factors that could affect the results of a septic dye test comes down to seller disclosure. In order for a septic dye test to give an accurate result, an assumption is made that the septic tank is full, and has not been emptied (pumped out) recently. If the tank has been recently pumped, it may not be full; therefore, the water that is run into the system to move the dyed water is simply filling the septic tank, and not pushing waste through the leach (absorption) field. If the entire septic system is not inundated with the dye solution, the test results are unreliable.
   Unfortunately, some home sellers do not disclose that the tank was recently pumped, and the integrity of the septic dye test is thereby compromised.

   Another factor that can affect the results of a septic dye test is the visibility of the ground surface in the area of the absorption field. If the area is overgrown with grass or weeds, any dye that migrates to the ground surface will not be easily observed. This can be a problem in the case of a foreclosed home that has not been maintained, or a home that has been on the market for a long time.
   In some cases (and not ALWAYS) the dye can discolor vegetation in the absorption field after a few days, since the dye is carried along with the water that the plants utilize in the area. If an area is overgrown with vegetation, it should be mowed before the septic dye test and cleared of debris so that the ground surface is more readily visible, assuring a more accurate test result.



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