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This article describes the types of trees, shrubs, or similar plants that should or should not be planted over or near septic fields or other septic system components. Planting trees, shrubs, and even some ground covers over septic system components are causes of septic system failure in the drain field, leach field, seepage bed, or similar components.

Planting Guidelines for Septic Drainfields, Mounds, Raised Beds, Septic Tanks and other Septic Components

Planting fruit trees, or vegetables (or anything else edible) over the septic drainfield might produce food that is unsafe to eat: see SEWAGE CONTAMINANTS in FRUIT / VEGETABLES for details.

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Guide to Planting Trees or Shrubs Near or Over Septic Absorption Systems

This is the only sort of tree that we suggest can be placed over septic system components with little risk of damage. This is actually a metal sculpture. Even the placement of this "tree" could have damaged a septic field if during its installation heavy equipment was used to deliver the tree to this spot. Real trees will damage septic components by root movement or clogging. If you have a shrub for which you have reliable knowledge about the maximum extent its roots will normally reach, you might think it’d be ok to plant it exactly that distance from the nearest drainfield trench. Watch out: the extra levels of nutrients delivered to the soils by the drainfield may attract roots from nearby trees or shrubs and cause them to travel farther than usual. OPINION: keep shrubs with a “known” root travel distance 25% farther than that distance from the edge of a drainfield.

How much distance is needed between trees and septic drainfields?

Whether you are planting trees or planning a new septic drainfield, keep the drainfield or septic leach field away from trees or shrubs which are likely to put down deep or aggressive roots. The roots will quickly invade and clog the buried effluent lines and may also cause them to move, break, or become disconnected.

The actual tree to septic distance needed depends on the tree variety and its normal root growth range. Keep at least as much distance between the tree and the nearest drainfield component as the anticipated height of the tree at its maturity. So if the tree will be 30' tall at maturity keep it at least 30' from the drainfield. Some trees should be kept at much greater distances, up to 100' from septic fields, as we discuss just below.

What kinds of trees should be kept farthest away from septic systems?

Trees considered to have deep and/or aggressive roots that are likely to damage a drainfield include:

• Bamboo, Beech trees Fagus sp. and Birch trees Betula sp.
• Cypress trees
• Elm trees Ulmus sp. and Eucalyptus
• Pepper trees
• Pine trees, such as Monterey pine. The pines in our photo (above-left) are white pines approximately 30 years old.
• Poplar trees Populus sp.
• Maple trees, particularly red and silver maples Acer rubrum and Acer saccharinium
• Walnut trees
• Willow trees Salix sp are popularly known for "liking water" and will certainly send out long root systems.

Kahn, Allen, Jones (book cited at Septic Systems Home-References) point out that certain of these trees such as bamboo, weeping willows, eucalyptus, cypress, Monterey pine, pepper, and walnut have particularly aggressive and deep roots. Keep such trees at least 100 feet from the nearest septic field component.

Can I Plant Non-aggressive Rooting Trees near Septic Drainfields?

Some trees have less aggressive roots and may do less rapid or less extensive damage if they are a bit nearer to septic fields. These include:

• Ornamental trees such as Cherry, Crabapple trees, and Dogwood trees.
• Other trees with less aggressive root systems such as Oak trees (red oak, scarlet oak, and white oak)
• Some Pine trees (but not the Monterey pine) and Sourwoods.

OPINION-DF: Some authors accept the near-septic use of these less aggressive trees with the advice that "... their damage is likely to be less severe". This seems silly to me. Any root clogging of septic systems is likely to be costly and inconvenient.

If you have a shrub for which you have reliable knowledge about the maximum extent its roots will normally reach, you might think it’d be ok to plant it exactly that distance from the nearest drainfield trench.

But I’d be careful: the extra levels of nutrients delivered to the soils by the drainfield may attract roots from nearby trees or shrubs and cause them to travel farther than usual.

OPINION-DF: I’d keep shrubs with a “known” root travel distance at least 25% farther than that "known root travel distance" from the edge of a drainfield.

Guide to Planting Trees near Septic Mound Systems

Some experts (Kahn, Allen, Jones) also point out that if you're planting on the edges and lower toe of a septic mound, those plants need to be able to tolerate the higher moisture levels found in those parts of the mound system.

In the photo at the top of this page, our field in northern Minnesota provided ample room to place septic system components more than 100 feet from the nearest tree. But what about those tire track that show up in light snow? Driving over the drainfield can also damage it.

Frequently-Asked Questions (FAQs) about recommended distances from septic drainfields to various trees and shrubs

Question: septic distances for Norway Pines & Red Spruce Trees?

Have you any information on Norway PInes and Red Spruce as i have these planted in my yard and am concerned about there potential damaging effects on my septic system......... thanks.... they r only 4 feet so far so i can transplant them if need be - Will Treeman (4/11)

Reply: 40-60 feet for a 20-40-year early tree-life range, longer for longer tree life expectancy

Tree distances to septic drainfield for red pine / Norway pines

According to Pennsylvania State University "The red pine is a native North American tree species sometimes erroneously called the "Norway pine". ... Red pines grow very rapidly for their first 60 or 70 years of life. They can live for up to 350 years and reach heights of 120 feet and diameters of up to three feet. " [1]

Using a 60-year planning time frame, and our rule of thumb for distances of normall-aggressive-root-system trees from septic drainfields, assuming a 60-foot tree height, I'd keep my red pines (or "Norway pines") sixty feet away from the drainfield. 100 feet would be safer as pines can have aggressive root systems.

Tree distances from septic drainfield for Red Spruce.

According to the University of Maine's Maine Tree Club, "Red spruce can attain a height of 60-80 feet and a diameter of 1-2 feet. It will occasionally exceed these measurements." Synonyms for red spruce include Yellow Spruce, West Virginia Spruce, Eastern Spruce, He-Balsam" Picea rubens, [2]

So the same rule of thumb as for red pines applies: if you don't want the trees to ever threaten the septic drainfield for the next 30-60 years, promising the trees a long and happy life, keep them 100 feet from septic drainfields.

Note: guessing at the tree root area and health for red spruce is complicated by soil chemistry and nutrients and so guessing root area size based on canopy size is less reliable for this species. [3]

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SEPTIC SYSTEM INSPECT DIAGNOSE REPAIR

PLANTS & TREES OVER SEPTIC SYSTEMS
  Gardens Near Septics
  Grasses or Flowers
  Grazing, Animals
  Ground Cover, Ivy
  Trees or Shrubs
  Using Root Killers
  Using a Roto Rooter

SEPTIC CLEARANCE DISTANCES

• "Planting Over Septic System Components", Daniel Friedman (author/editor, InspectAPedia.com), The Innovator, Winter/Spring 2008, BCOSSA, British Columbia OnSite Sewage Association, 201-3542 Blansard St., Victoria BC V8X 1W3 Canada
• "Planting on Your Septic Drain Field", Susan D. Day, Extension Associate; Ellen Silva, former Extension Technician; Horticulture, Virginia Tech. publication Number 426-617, Posted December 2000, published by the Virginia Cooperative Extension
• Escherichia coli O157:H7- US CDC
• Demistifying Ecoli - Federation of Ontario Cottagers
• Microbiology home page - US EPA
• Septic System Drainfield Absorption System Biomat Formation - what leads to drain field clogging and expensive drainfield repairs
• Septic Contaminants, identifying - what are the Nitrogen contaminants produced by septic systems and what can be done about them if they escape initial treatment?
• Septic Tank Pathogens in Sludge and Floating Scum: what makes up the contents of residential sewage
• Measuring Septic Sludge & Scum Levels in Septic Tanks - Measuring the Level of Accumulated Solids, Sludge and Floating Scum in Treatment Tanks
• Sewage and Septic Contamination in Residential buildings - inspecting and testing for bacterial contamination after a sewage spill: consumer information and expert resources
• Septic Flood Response when and what to do to a septic system after area flooding
• Remediation of Sewage Contaminated Crawlspaces - Byjim Holland, CR, "Cleaning and Restoration," July 1999, pp 22-24
• Escherichia coli O157:H7- US CDC
• Cost effective testing for blackwater contamination in buildings Aerotech Labs
• Indicator organisms, testing for sewage contamination in buildings Aerotech Labs
• [1] "The Virtual Nature Trail at Penn State New Kensington", the Pennsylvania State University, 2002, web search 04/30/2011 original source: http://www.psu.edu/dept/nkbiology/naturetrail/speciespages/redpine.htm
• [2] "Main Tree Species Fact Sheet: Red Spruce (Yellow Spruce, West Virginia Spruce, Eastern Spruce, He-Balsam" Picea rubens, The Maine Tree Club, University of Maine, http://extension.umaine.edu/mainetreeclub/FactSheets/even-year-htm/RedSpruce.htm
• [3] "Vitality and chemistry of roots of red spruce in forest floors of stands with a gradient of soil Al/Ca ratios in the northeastern United States", Philip M. Wargo, Kristiina Vogt, Daniel Vogt, Quintaniay Holifield, Joel Tilley,
  Gregory Lawrence, and Mark David", NRC Research Press, NRC Canada 2003. The relationship between the root area (and vitality) and tree crown area is complicated by soil chemistry and other factors and may be more difficult to guess by rule of thumb. - http://www.nrcresearchpress.com/doi/pdf/10.1139/x02-195

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

• Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
• Inspecting Septic Systems: Online Book, Inspection, Test, Diagnosis, Repair, & Maintenance: our Online Septic Book: Septic Testing, Loading & Dye Tests, Septic Tank Pumping, Clearances, details of onsite waste disposal system inspection, testing, repair procedures.


• Advanced Onsite Wastewater Systems Technologies, Anish R. Jantrania, Mark A. Gross. Anish Jantrania, Ph.D., P.E., M.B.A., is a Consulting Engineer, in Mechanicsville VA, 804-550-0389 (2006), Advanced Onsite Wastewater Systems Technologies. Outstanding technical reference especially on alternative septic system design alternatives. Written for designers and engineers, this book is not at all easy going for homeowners but is a text we recommend for professionals--DF.
• Builder's Guide to Wells and Septic Systems, Woodson, R. Dodge: $ 24.95; MCGRAW HILL B; TP; Quoting from Amazon's description: For the homebuilder, one mistake in estimating or installing wells and septic systems can cost thousands of dollars. This comprehensive guide filled with case studies can prevent that. Master plumber R. Dodge Woodson packs this reader-friendly guide with guidance and information, including details on new techniques and materials that can economize and expedite jobs and advice on how to avoid mistakes in both estimating and construction. Chapters cover virtually every aspect of wells and septic systems, including on-site evaluations; site limitations; bidding; soil studies, septic designs, and code-related issues; drilled and dug wells, gravel and pipe, chamber-type, and gravity septic systems; pump stations; common problems with well installation; and remedies for poor septic situations. Woodson also discusses ways to increase profits by avoiding cost overruns.
• Country Plumbing: Living with a Septic System, Hartigan, Gerry: $ 9.95; ALAN C HOOD & TP; Quoting an Amazon reviewer's comment, with which we agree--DF:This book is informative as far as it goes and might be most useful for someone with an older system. But it was written in the early 1980s. A lot has changed since then. In particular, the book doesn't cover any of the newer systems that are used more and more nowadays in some parts of the country -- sand mounds, aeration systems, lagoons, etc.

Design Manuals for Septic Systems

• US EPA Onsite Wastewater Treatment Systems Manua [online copy, free] Top Reference: US EPA's Design Manual for Onsite Wastewater Treatment and Disposal, 1980, available from the US EPA, the US GPO Superintendent of Documents (Pueblo CO), and from the National Small Flows Clearinghouse. Original source http://www.epa.gov/ORD/NRMRL/Pubs/625R00008/625R00008.htm Onsite wastewater treatment and disposal systems, Richard J Otis, published by the US EPA. Although it's more than 20 years old, this book remains a useful reference for septic system designers. U.S. Environmental Protection Agency, Office of Water Program Operations; Office of Research and Development, Municipal Environmental Research Laboratory; (1980)
• Eco John® Innovative Toilet Solutions, Global Inventive Industries, Fountain Valley CA, PDF, product brochure
• "International Private Sewage Disposal Code," 1995, BOCA-708-799-2300, ICBO-310-699-0541, SBCCI 205-591-1853, available from those code associations.
• "Manual of Policy, Procedures, and Guidelines for Onsite Sewage Systems," Ontario Reg. 374/81, Part VII of the Environmental Protection Act (Canada), ISBN 0-7743-7303-2, Ministry of the Environment,135 St. Clair Ave. West, Toronto Ontario M4V 1P5 Canada $24. CDN.
• Manual of Septic Tank Practice, US Public Health Service's 1959.