Guide to Planting Trees or Shrubs Over or Near Septic System Components

Photo-illustrated guide to trees or shrubs planted near septic systems
- Advice for planting over or near septic systems
PLANTS & TREES OVER SEPTIC SYSTEMS
Questions & Answers about recommended distances from septic drainfields to various trees and shrubs
References

Click to Show or Hide Related Topics

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

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.

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

Photograph of a tree which can be placed over septic system components

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.

Photo of a failed septic field with nearby trees.
In this photo the light and excavated area is where the new home owner saw and dug into a smelly wet spot that appeared in the yard the morning after moving into their new home - a house built 30 years before and one which employed a home made septic tank.

While there were tree roots in the drainfield pipes of the system, the septic tank itself, which was too small, never pumped, and fully blocked, was the "root" cause of system failure in this case. (Pardon the pun).

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.

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.

Shrubs or Trees Recommended as Suitable for Planting Over / Near Evaporation-Transpiration Septic Systems

The following table of native (to New Zealand) or introduced species of shrubs and trees lists species that are considered suitable for planting over an evapo-transpiration system and should be acceptable over a mound system or conventional drainfield as well. Note that other native species local to your area might also be suitable. [3] Separately at Grasses or Flowers we provide a similar table of suitable grasses.

Table of Shrubs or Trees Suitable for Planting Over / Near Evaporation-Transpiration Septic Systems [3]
Common Name	Botanical Name	Comments
Aralia
Begonias
Cabbage tree	Cordyline Australias	fast growing
Canna lilies
Coprosma	Coprosma propinqua
Flax	Phormium Tenax	fast growing
Fuscia
Hebe	Hebe
Heketara	Olearia Rani
Kohuhu	Pittosporum Tenufolium	fast growing
Lacebark	Hoheria Populnea	fast growing
Pokaka	Elaeocarpus Hookerianus	slow growing
Rangiora	Brachyglottis Repanda	fast growing
Ribbonwood	Plagianthus Regius	fast growing
Manuka	Leptospermum Scoparium
PhilodendronsPoataniweta	Carpodetus Serratus
Taro
Weeping mapou	Myrsine Divaricata
Notes: Original source: "Looking after your household sewerage system," New Plymouth District Council, Taranaki NZ, [3] Also see Grasses or Flowers ok to plant over septic systems and drainfields or soakaway beds.

...

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]

Ask a Question or Search InspectApedia

Questions & answers or comments about recommended distances from septic drainfields to various trees and shrubs.

Ask a Question or Enter Search Terms in the InspectApedia search box just below.

Technical Reviewers & References

Related Topics, found near the top of this page suggest articles closely related to this one.

"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
[3] "Looking after your household sewerage system," New Plymouth District Council, Taranaki NZ, newplymouthnz.com, retrieved 4/4/13, [copy on file as Septic_Maintenance_Taranaki_NZ.pdf]
Escherichia coli (E-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, original source: restcon.com/links/articles/Remediating%20Contaminated%20Crawlspaces.pdf
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
"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.

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.

The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.

Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page "Promo/Redemption" space.


	InspectAPedia^®	Question? Just ask us!	InspectAPedia
Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair

Question? Just ask us!

Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair