Septic dye indicating a failed septic drainfield (C) Daniel Friedman Failed Septic System Drainfields as a Source of Septic Odors or Smells

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Odors from the septic drainfield or soakaway bed: this article explains how to diagnose & correct sewer gas or septic odors (and other building smells and odors traced to a failed septic drainfield, leachfield or soakaway bed. Some of the diagnostic steps pertain to all seasons, others to cold weather conditions.

The photograph at page top shows green septic dye appearing in a septic system drainfield during a septic loading and dye test. Even before we performed this test to confirm that the liquid found on the surface of the drainfield area was indeed septic effluent (coming from the septic tank), sewage odors in the drainfield area outdoors told us that the septic field was in trouble. Also see our broad-scope article on diagnosis and cure of sewer gas and septic odors: Sewer Gas Odors diagnosing, finding, and curing septic tank and sewer line smells.

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How to Investigate & Repair Failed Drainfields and Septic Odors

Failed drainfield by a pool (C) Daniel FriedmanNotice sewage odors present outdoors, strongest in and traced to the known or most-likely area for the septic drainfield or leach field, also called the soakaway bed or soil absorption system.

[Click to enlarge any image]

Look for wet areas in or near the septic drainfield. Consider performing a septic loading and dye test to confirm that the wet areas found are septic effluent from the septic tank.

Even if wet areas around a septic leach field are local ground water or runoff, the added water load that those conditions place on the septic drainfield may themselves constitute a septic failure or may require site work to redirect those water sources away from the drainfield.

If the septic system drainfield is blocked or failed it may be possible to reroute effluent to an un-used or under-used section of the drainfield (if effluent was not being distributed uniformly in the first place) - check the distribution box (if any).

photo of a septic distribution box used to connect the septic tank effluent outlet line to a network of
drainfield pipes

There will be additional evidence of septic field condition in the D-box; if the box is flooded either these lines are blocked (such as by poor, uneven installation, tree roots, or a collapse, something not too likely unless you drove a truck over the fields), or the field has stopped percolating and needs replacement.

If on opening the D-box or excavating a drainfield line you see standing water in the leachfield line, either the field is saturated - lost perc - or the line has collapsed nearby and is not flowing.

You can test this by running a hose into the leach line from the D-box or from your point where you've cut it open.

Sometimes you'll see that only one field line is saturated and failed - you can close it off in the D-box and just use the others to give the saturated one a rest, but at the end of the day, you probably need a new drainfield.

See SEPTIC D-BOX INSTALL REPAIR for help in finding and inspecting the septic system drainfield distribution box.

Septic Repair Shortcuts and Septic Treatment Products and "Magic bullet" septic repair products and procedures like chemicals, additives, root killers, or soil restorers are mostly ineffective, waste money, and in some cases are illegal as they contaminate the environment. If the septic system drainfield is blocked or failed, most often the property needs a new drain field.

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