LARGER VIEW of a septic system sketch that helps understand conventional tank and drain field design. Private Sewage Disposal Systems - Septic Drawing Library

  • SEPTIC DRAWINGS - CONTENTS: Septic system drawings, sketches, plans . Illustrations of basic land forms and how they affect septic system installations. Illustrations of septic tanks. Illustrations and sketches of septic system distribution boxes, drainfields, lines. Sketches of leach fields, seepage pits and other onsite waste disposal systems
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Septic system drawings: Here are some sketches explaining septic system components and installations. These septic system illustrations help readers understand, identify, and possibly even locate buried onsite wastewater disposal and septic tank equipment at properties. Some of the illustrations also show why septic systems, particularly drainfields may not be working. These drawings are for educational purposes and are not engineering plans or specifications.

Click on the thumbnail sketches below to see each full-sized illustration. This website is provided as a non-profit public educational service - intended for on-line study.

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Septic System Illustrations, Sketches, Design Layout Drawings & Examples

The color sketches below are courtesy of Purdue's Environmental Education Software Series. Educational software on diskettes is available from the Farm Building Plan Service, 1146 AGEN Building, Purdue University, W. Lafayette, IN. The black and white sketches are courtesy of Carson Dunlop Associates. The illustrations are shown here for educational purposes - are all © copyright protected and may not be duplicated or reproduced in any fashion, printed or electronic, without prior written permission.


The contents & illustrations seen here are all © copyright protected - If you see our material elsewhere please let us know.

Basic LandformsBasic landforms.

Water Table 1Leaching bed effluent distribution schema

Water Table 2Water table well below leaching beds

Water Table 3High clay, likely problems of limited capacity

Water Table 4Mounding water table subverts leaching bed


Septic tank

Septic tank A typical septic tank , cross section.

Septic sketch 1 Two types of commonly-used pre-cast concrete septic tanks, in cross-section.
Sketch courtesy of Carson Dunlop Associates, Toronto, Ontario


Absorption Field Typical absorption field (aka leach field, leaching bed).

Distribution BoxDistribution Box typical location.

Trench cross sectionPlan view gives cross section of typical leaching bed trench.

Septic sketch 1

Isometric sketch of tank and distribution lines, gives an idea why you need a distribution box.

ABSORPTION SYSTEMS - Leach Fields, Seepage Pits, etc

Click on the thumbnail sketches below to see each full-sized illustration.

Septic sketch 1

A somewhat unusual view from the "far-end" of a typical tank and leaching-bed system.

Photograph of  a septic effluent seepage pit

Elevation-view sketch of a tank and drywell or leaching pit or "seepage pit" system used at some older homes. In this illustration the seepage pit is being used to dispose of septic effluent from a septic tank.

Photograph of  a seepage pit used as a drywell for graywater

Elevation-view sketch of a drywell or leaching pit or "seepage pit" system used for gray water. In this illustration the seepage pit is being used to dispose of graywater from non-sewage carrying drains such as a laundry, sink, or shower. Drywells to handle graywater separately from blackwater (sewage) are often used to reduce the water load on septic systems which have a limited effluent handling capacity. If the pit shown in this sketch were receiving sewage and blackwater from a building we would call it a cesspool, not a drywell.

Sketch of common residential tank and leach-field layout


Elevation-view and a second, plan-view sketch of common residential tank and leach-field layout.

The septic consultants who are listed at SEPTIC CONSULTANTS can provide that service for both traditional and alternative onsite waste disposal system designs. Other documents throughout our website include photographs of various septic system components, site conditions, septic test and inspection tools, etc. To suggest needed sketches or to contribute drawings to this library contact us. Our main websites are at the bottom of this page.


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SEPTIC DRAWINGS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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