How to Spot Unexpected or Odd Septic Drainfield Locations
How to find the septic leachfield or drainfield when it is in an unusual or unexpected location. This article series and our accompanying septic system location videos explains how to find the leach field or drainfield portion of a septic system. We include sketches and photos that help you learn what to look for, and we describe several methods useful for finding buried drainfield components. (Septic drain fields are also called soil absorption systems or seepage beds.)
In the page top photo you can see septic effluent running across a rocky surface during our septic loading test. Actually effluent was running across this rock before we began our septic test, but our dye succeed in proving that the wet area was indeed coming from a failed septic system. A conventional tank and drainfield could not work in this location.
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Remember that septic system components can be at an "illogical" or "unlikely" location since people often make expedient or otherwise bad design choices, or may have had no alternative.
We've found drainfields that were quite remote from the building and from the septic tank, more than 200' away (downhill).
The reason this is abnormal is that it is expensive and trouble to dig great distances and there must either be proper slope (elevation change) between the tank and drainfield, or a pumping system is needed.
So normally the septic contractor will not put a septic system component farther away from the building or the tank than is necessary.
But rocky sites, steeps slopes, ponds, or other site features may mean that the tank or drainfield are located surprisingly far from the building they serve.
We've found leaching beds that were located across a public highway from the house and septic tank. We've found leaching beds that were not on the owner's property at all.
Especially at older, unsupervised, or remote rural properties, the temptation to simply route effluent leaving the septic tank to a stream, lake, pond is sometimes overwhelming (though unsanitary and illegal).
This is particularly true at sites where the soils into which one would have to put the drainfield are rocky, wet, or where the drainfield has previously failed.
In the photo you can see that this septic tank is less than ten feet from a lake.
For example, at properties along Wappingers Creek in Dutchess County, NY, many of the homes located their drainfields downhill from the house and too close to the creek. In times of spring rains the creek floods and floods the drainfield area. These are not working drainfields and are unsanitary.
At a home inspection at one of these properties we found that the previous owner had installed a straight pipe from the end of his failed drainfield right into the creek. Our septic loading and dye test was turning Wappingers Creek a reddish pink!

We've also found that there was in fact no leaching
bed at all - simply a short perforated pipe into the ground next to a septic tank, or worse,
an illegal pipe to a storm drain, creek, or to the surface of a hillside.
This farm property, which we were inspecting outside Frankfort, Germany in 1968, had toilets but no working drainfield at all.
Watch out.
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