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How to Spot Areas Where one Should Not Expect to Find (nor Locate) the Septic Drainfield InspectAPedia®  -

• How to find the septic drainfield or leach field
• Video here shows where septic system components are probably not located
• Where not to expect to find septic system components

This article 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.) Also see How to Find the Septic Tank.

The septic system video#4 at right describes walking a homesite by a lake in order to reason that the drainfield, which must be not only uphill from the lake but in this case uphill from the septic tank too, cannot be located in the front yard, even though that looks attractive for a drainfield. In the center of the yard we spot the well casing - end of story. The septic field should not be located here.

A septic pumping system will be needed and the drainfield will have to be located elsewhere on the site, and at a good distance from the well. More videos on septic system location & maintenance are at SEPTIC VIDEOS.

Uphill areas, area

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This is a chapter of Inspecting, Testing, & Maintaining Residential Septic Systems an online book on septic systems.

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A Guide to Finding the Drainfield - Part 5

What areas are least likely to contain the drain field, or if they contain a drainfield, are likely to be a problem?

Site areas too close to a drinking water well cannot be used for septic drainfields. See Table of Required Septic Tank, Drainfield, & Well Clearances if you need to reference typical septic component clearance distance guidelines. Our video at the top of this page demonstrates how we discover where the well is located and why that should preclude finding the septic fields in an area that otherwise looked pretty attractive.

Uphill areas, areas that are higher than the elevation of the septic tank are unlikely to contain the drainfield. Unless a septic pump or effluent pump system are installed (you'd find wiring, and perhaps alarms) the drain field is going to be at or below the elevation of the septic tank. In other words, down hill from the septic tank since effluent has to enter a conventional drainfield by gravity..

Naturally nothing prevented the installer from burying the leach lines very deeply in an area which is, on the surface "uphill" from the tank, but this would be an extra costly installation (more excavation) and also it would violate good design (leach trenches too deep).

Rocky areas like this should not contain a septic drainfield but sometimes they do - even though a conventional septic system won't work on rock: such as the failed septic system shown at left, and areas where bedrock is exposed on the surface won't make a normal absorption field.

But beware, we've found non-functioning systems installed in just such a location as the rocky, steep site shown in the photo at left. The wet marks were water from the septic system leaking across the hillside.

At the upper center of this photo you can see straw that the owner's contractor piled atop of the septic tank in anticipation that any problems would be hidden from view.

All we had to do was walk downhill at this steep rocky site to see these signs of a totally inadequate septic system installation

• Septic effluent running over bare rock
• Bare bedrock so close to the soil surface that no working septic drainfield could be installed here without considerably more fill
• A septic tank overflow pipe that spills directly onto the soil surface - visible at the bottom center of the straw pile

Swamps or low wet areas, unless the site is using a constructed wetlands for effluent treatment (such as we show in this area of Mexico in our photo at left) should not contain conventional drainfields.

If the septic fields are too close to a wet area like this the property may be disposing of septic effluent but a conventional tank and drainfield spilling untreated wastewater effluent into a swamp, stream, or lake, is not properly treating it and is contaminating the environment.

Areas with Trees: thickly forested areas are unlikely to contain a drainfield, first because of the tree root-drain-clog problem and second because the backhoe operator would have a heck of a time manipulating the excavation equipment in such a tight area. If there is no room to operate a backhoe it is unlikely that there is a recently-installed drainfield in that area.

This area on a homesite in the Northern U.S. is an unlikely spot to place a drainfield - certainly the presence of trees close together means a backhoe has not been in here digging in many years.

But don't rule out a very old, overgrown, and ruined drainfield in such a spot at an older property.

Site areas too close to a drinking water well cannot be used for septic drainfields, as we demonstrate in our site-walking septic-locating video at the top of this page.

Our septic search photo at left shows that some well locations are pretty obvious - we don't expect to find the septic tank or drainfield within 75' to 100' of this spot - but we might, depending on the age and size of the building site.

Sites too close to a lake or stream should not contain the septic tank and certainly not the drainfield - but they might

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. We discuss this problem installation further at Surprising Leachfield Locations.

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Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

SEPTIC DRAINFIELD LOCATION
  Why Look For the Drainfield?
  Using Septic System Records
  Where to Look
  Areas Not Likely
  Locate Piping Precisely
  Excavating to find Drainfield
  Surprising Leachfield Locations
  SEPTIC VIDEOS show how to find the drainfield and tank

Detailed Guide for Finding Other Septic System Components

More Information on Building Diagnostic Inspections and Repairs

• The Septic System Information Website home page for septic system design, installation, maintenance, repair
• Buyer's Guide Home Buyer's Guide to Septic Systems Inspection & Testing - What to Do, Step by Step.
• Septic Drainfields, Leach beds, Drwells, Absorption Systems
  • Absorption Field Design size and specifications for leach fields, absorption beds, gravelless systems, seepage pits
  • How Big Should the Leach Field Be? - table of soil percolation rate vs. field size
  • Planting Over Septic Systems: trees, shrubs, groundcover over the septic system: what can you plant over or near septic system components without causing a problem?
  • Septic System Drainfield Absorption System Biomat Formation - what leads to drain field clogging and expensive drainfield repairs
  • Table of Required Septic Tank, Drainfield, & Well Clearances: Distances Between Septic System & Wells, Streams, Trees, etc
  • SEPTIC SYSTEM DESIGN BASICS
  • Septic System DESIGN ALTERNATIVES
• Septic Tank Location - How to Find the Septic Tank, how deep will the cover be, how to document its location
• Septic Tank Pumping Guide: When, Why, How to pump the septic tank
• How to Measure the Distance From the House to the Septic Tank gives details of making a septic location sketch.
• Distribution Box design, inspection, testing, and maintenance of the septic system D-box

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