Frequently-asked questions & answers about sewage pathogens appearing in fruits and vegetables grown near septic disposal fields:

Here we answer FAQs about the risk of sewage or septic effluent contamination of fruits, vegetables, or other edibles grown near septic drainfields or aerobic septic systems.

This article series discusses the health hazards of consuming fruits and vegetables that may contain contaminants produced if they are grown over septic drainfields or too close to other sources of effluent from septic systems or on-site waste disposal systems

FAQs on Sewage Contaminants in Fruits and Vegetables Grown Near Septic Drainfields?

These questions & answers about risk of garden or fruit contamination from septic systems were posted originally at SEWAGE CONTAMINANTS in FRUIT / VEGETABLES - you will want to review that article.

On 2019-04-02 by (mod) - Growing in fill in boxes above a drainfield

Growing in fill in boxes above a drainfield may not produce contaminated vegetables,

BUT adding 16" of soil atop a drainfield will reduce its ability to dispose of moisture by transpiration and evaporation - ultimately risking damaging the fields.

On 2019-03-16 by ann

I have multiple raised bed vegetable garden boxes 16" high, built over glacier til. It's so rocky and completely devoid of dirt that I brought in 6-8" of top soil some 30 years ago.

Recently I discovered that one veg box is running length-wise along one leg of my cement pipe drainfield. Being a raised bed system of 16" deep boxes, sitting on a minimum of 6" topsoil, with hazelnut shells over the pathways between the boxes;

I'd like to know if the lettuce & spinach in the box over the drainfield pipe safe to eat? What about the vegetables (short carrots to tomatoes) planted in the other boxes not directly on top of the drainfield pipe? I live in the liquid sunshine state of Western WA.

On 2019-01-10 by (mod) -

LR

At SEWAGE CONTAMINANTS in FRUIT / VEGETABLES you will find the homepage for this topic

Take a look at that article as it may be helpful to you.

You'll see that many experts are of the opinion that the risk from sewage on ground surfaces is from rain splash or dust contamination that gets onto edible foods not so much from pathogens or chemicals traveling through plant roots.

Nevertheless my opinion which is not an authoritative remark is that I wouldn't eat avocados that have been on the ground in sewage, fix skin soap and water or not. I'm just not confident in the cleaning process that you need to use.

However to be fair, here in Mexico we regularly first wash our fruits and vegetables to remove any surface dirt or debris and then we second disinfect them using a disinfectant solution that is intended for that purpose. So if you need to salvage your lazy on ground avocados that's the approach you should take.

On 2019-01-10 by L.R.

Our sewer line from house goes right under our avocado tree. We had a temp cleanout, but line backed up so bad the soil around tree was flooded with sewer water during a rain storm.

Are the avocados safe to eat? Is is safe to eat any fruit that hits ground while I am harvesting fruit if it doesn't break skin & is washed? I'm not sure how porous avocado skin is, or how dangerous soil is around tree now. The plumber put his bare arm elbow deep in a hole filled with sewage & rainwater....so wondering just how dangerous it is.

On 2018-03-16 by (mod) - . I would like to plant over septic field using some Feed Bunks.

It's an interesting idea that I wouldn't rule out though I'm not sure what plants will survive in the volume of soil you could put in to the feed bunks.

There are still some concerns, Aldo such as

= weight of equipment moving around your planting

= excess water over the drainfield during planting watering that then saturates the fields

On 2018-03-16 Aldo said:

Hello. I would like to plant over septic field using some Feed Bunks. These would work as raised planters that would keep them at least a foot above the ground. Do you think this would be a safe alternative so I could plant vegetable in the Feed Bunks? Here is the link for the bunks so you can see what I'm considering using.
...
I'll eagerly await for your comments. Thank you. -Aldo

IMAGE LOST by older version of Comments code - now fixed. Please re-post the image if you can. Sorry. Mod.

On 2017-05-08 by (mod) -

I can't say, Deborah; if there are root vegetables in sewage or if sewage splashes or is air transported by dust onto edibles there could be hazards; I would start with a call to your local health department since open sewage isn't permitted and is a hazard to not just your veggies but to people in the neighborhood too.

On 2017-05-08 by Deborah l Burman

There is sewer leaking in an area in my back yard. I put a garden in outside of our fence away from leak will my vegetables be alright?

On 2017-03-18 by (mod) -

Andrea

About kinda-science, at the bottom of any InspectApedia article, where you see the heading

Technical Reviewers & References

you'll see additional supporting research citations that didn't make it into the article main text - principally for economy of viewing space.

On 2017-03-17 by Andrea

Lol! My friend, I'm lost in a Google forest of gleen kinda science where people's "researched" (because in Twitter and the National Enquirer we trust) 2 bits resemble less the train wreck it used to be and has graduated to a bright orange Trump Trolly. Bread crumbs can lead a girl home. Don't downplay, giving me material that is ACTUAL research means you rock socks clean off a body. Thanks bunches for that, it's always fun to watch ones appendage coverings spontaneously evacuate the space in which said appendages are currently residing. See? I be edumacated too yo. 'MURICA!!

On 2017-03-14 by (mod) -

Andrea

Aw gee, I'm disappointed if our articles seem to offer just crumbs. I'll welcome questions, critique, content suggestions, references, citations that expand the information in this article series.

I've not found research on the effects of septic effluent on insects and on birds that eat them, though I suspect those risks are far less than the hazards of pesticides for those two populations.

A scholarly search for "impact of septic effluent on insects" doesn't turn up a perfect research article or book; most of the research is on effects of sewage effluent on groundwater and aquatic life, including aquatic insects. I give some examples below. Be sure to see Hawkes (1955)

• Goudreau, Stephanie E., Richard J. Neves, and Robert J. Sheehan. "Effects of wastewater treatment plant effluents on freshwater mollusks in the upper Clinch River, Virginia, USA." Hydrobiologia 252, no. 3 (1993): 211-230.
• Gaufin, Arden R. "The use and value of aquatic insects as indicators of organic enrichment." BIOLOGICAL PROBLEMS (1956).
• Hawkes, H. A., and M. R. N. Shephard. "The effect of dosing-frequency on the seasonal fluctuations and vertical distribution of solids and grazing fauna in sewage percolating filters." Water Research 6, no. 6 (1972): 721IN3723-722IN4730.
• Hawkes, H. A. "The effects of methods of sewage application on the ecology of bacteria beds." Annals of Applied Biology 47, no. 2 (1959): 339-349.
• Hawkes, H. A. "The effect of periodicity of dosing on the amount of film and numbers of insects and worms in alternating double filters at Minworth, Birmingham." Jour. and Proc., Inst. Sew. Purif., Part I (1955): 48.
• Pettry, D. E., R. B. Reneau Jr, M. I. Shanholtz, S. A. Graham Jr, and C. W. Weston. "Soil pollution and environmental health." Health services reports 88, no. 4 (1973): 323.
• Canter, Larry W., and Robert C. Knox. Evaluation of septic tank system effects on ground water quality. US Environmental Protection Agency, Robert S. Kerr Environmental Research Laboratory, 1984.
  
  
  

On 2017-03-14 by Andrea

Thanks so much for the great bread crumbs and links to more info, I knew I was sounding off the right board. To clarify, I wanted to plant the wild flowers directly in the spray field

, I need pollinators around and since that but if land is a no go area I thought it would be a good spot for wild native blooms ( NOT for cuttings) once it's seeded the only thing going into that spray field ( other then wild critters) are the septic maintenance company if the sprinklers need service. It sounds like a great idea

but I wonder what the good bugs might pass along to the surrounding gardens.

If your original thoughts still stand then we're golden- I'll plot it out after a bit more planning and when edible stuff starts growing elsewhere on property I'll get things tested to see if the minute amount of contamination from the pollinators even matters. Thanks again and rock on

On 2017-03-12 by (mod) - safe distances from aerobic system for hazelnut trees & wildflowers

Thank you for the nice comment, Andrea. In an era of fake news and loss of appreciation of the importance of objective facts, we can but increase our commitment to doing our best to provide accurate, un-biased information.

About planting wildflowers over a septic area out of the spray area, I think that's a fine idea. From my reading, the greatest concern with septic effluent contamination would be either direct spray onto edible crops or contaminated soil-splash-up onto them. But do consider prevalent wind direction and force - that may lead you to use a somewhat greater safety distance from the drainfield.

GARDENS NEAR SEPTICS at https://inspectapedia.com/septic/Plant_Garden_Over_Septic_Fields.php adds some detail about such plantings right over or close to septics (not your case)

About planting trees near the septic field, with enough distance that you're not splashing contaminated soil nor wind-drifting septic effluent onto the trees, the remaining question will just be root damage to the fields - unlikely if you're far enough away. "Safe" distances (about root damage) ranges from 50 to 100 ft. depending on tree species.

There are many on-line sources of advice on growing hazelnut trees. You need at least two trees, and typical planting spaces gives each tree 20x20 ft. So if you're 50 feet from a fence that marks the perimeter of your effluent absorption area you should be OK. It'd be smart to double check about hazelnut root growth patterns with an arborist.

See Baron, Lloyd C., Craig Riggert, Robert L. Stebbins, and Susan M. Bell. "Growing hazelnuts in Oregon." (1985).

see TREES or SHRUBS OVER THE SEPTIC FIELD or TANK at https://inspectapedia.com/septic/Plant_Trees_Over_Septic_Fields.php for some distance guidelines. You'll see that safe distances to avoid root damage depend on the tree or other plant species.
There you will also find a link to a PDF file describing procedures for growing Hazelnut trees, prepared by Henry and Kaiser for the USDA.

InspectAPedia is an independent publisher of building, environmental, and forensic inspection, diagnosis, and repair information provided free to the public - we have no business nor financial connection with any manufacturer or service provider discussed at our website. We do not sell products nor services.

We are dedicated to making our information as accurate, complete, useful, and unbiased as possible: we very much welcome critique, questions, or content suggestions for our web articles. Working together and exchanging information makes us better informed than any individual can be working alone.

On 2017-03-12 by Andrea

Hi there, I really appreciate this forum- it's hard to find educated answers you haven't paid for out the nose for that try to cover so many variables with such effort and honesty as I've read on here. Before I ask my question I just wanted to say your restraint from giving in to trolls so as to answer their real questions is awesome.

So with that said here's my question, I'm hoping for a few good points to pursue because I've no idea where to start with an answer. I have an aerobic septic system with two sprinklers that spray gray water. The plan is to fence of the area of farthest spray reach and seed wildflowers for pollinators (I live in Texoma, pasture land). I'd like to plant hazelnut trees for consumption about 50ft away from fence.

I'm worried about food safety

. Im considering hazelnut because I'd need to bake it before eating ( to remove skin) and I'm hoping that approach will give me a safe end product for flour and animal feed (geese and chickens as a treat and winter staple. Don't mind cooking/skinning as it makes crushing easier.) What are your thoughts? I'm thinking worst case scenario hazelnut crop experiences splash up but not soaking. Very possible run off during rain from fenced area to tree roots.

Small property of 2 acres, 2 adults 4 children to give you an idea of septic loads, co-op well water, no large livestock.

On 2016-08-30 by (mod)

The concern would be more likely whether or not sewage effluent splashes up onto the grapes during rainfall - if the tank is sealed and the drainfield is not in failure you may be ok.

On 2016-08-30 by can u eat grapes planted near septic tank

i have concord grapes growing close to septic tank can i make jelly and be safe to eat

On 2015-12-28 by Anonymous

Test the produce for sewage bacteris, keeping in mind that changing weather or change in septic field conditions still can create a contamination risk.

On 2015-12-27 by Karen

Testing I can do, but I'm at a loss as to what tests. Would the local extension office be the best place to go? Would they know of regulations regarding selling to the public?

It seemed most people were talking about being very close to the system whereas I think I'd be at least 100 feet away (I'll need to find out exactly where the system ends).

I'm inclined to think that would be sufficient but don't want to go through the effort & expense to plant trees if I can't sell the fruit. Thank you for your time and input; I'm so glad I found this site!

On 2015-12-26 by (mod)

"Near" is not a fixed number so I agree the discussion, even from experts, can be confusing; whether or not edibles will be contaminated depends on not just distance but soil properties, water flow rates through soils, rain splash-up, dust transport, etc.

I think some common sense and perhaps some testing can answer the question.

On 2015-12-26 by Karen

After reading all of the posts above the first question that comes to mind is "What is NEAR?" I know of a piece of land, I'd guess about 450' x 450', with a mound at one end of it. If fruit trees were planted in the center of that square would they be "near" it? If planted at the other end of it would they be "near" it?

Are there government entities (or others) who regulate how far away you must plant in order to be "safe" to sell your harvest to the public?

Question: we have constructed a vegetable garden or plantd fruit trees over the drainfield but now we're worried

(Sept 10, 2011) Anonymous said: hey what about if waste water went in a lemon tree ?can we eat the lemons or is it dangerous

(Mar 9, 2012) Anonymous said: Large new drain field. Family 4. Orange tree 15 feet from tree to in ground drain field with lift station. Only brown water from lift station. Safe or not safe.

(Apr 28, 2012) RICK said: LEMON TREE OR NUT TREE 15' AWAY FROM LEECH FIELD-IS IT SAFE TO EAT????

(July 31, 2012) tanya said: Hi there we have a community growing area,we have small ground level plots that we have been growing our veg in, sadly last night we were flooded by the local brook/dike, leaving a dark brown mud and foul smell, would it be safe to eat these vegtables as many were potatoes or should we destroy and start again?

Would these areas need to be have fress top soil incase of sewage damage or could we clean it, any advice would be great

(Jan 25, 2013) Jennifer said: We recently rebuilt a house in a large, old, established residental hilly area, at the very bottom. There was a water drainage problem, which has been corrected as best we can. Still very high underwater flow. Is it safe to plant veggies/herbs in this area?

4/24/2014 Summer Costello said:

We have prepared a large site for growing vegetables in a nice flat spot of our yard following guidelines for "Eden" gardening. We started with a layer of newspaper right on top of the grass, followed by a layer of decomposed cow manure, added in some mushroom mulch, and finally three inches of wood chips. We began this process last fall in excited preparation for planting this spring.

Recently, however, a visiting plumber noted that our garden plot is situated directly over our drainfield and could produce vegetables that are unsafe to eat. We were so disappointed and began researching to confirm or disprove his concerns. I read most of the pertinent info on your website, but still have some questions.

1) Since our plot has been prepared over the grass and vegetables will not be planted directly into the soil, will this reduce the possibility of contaminants in the veggies?

2) Should't the wood chip layer adequately protect veggies from contaminant splash up?

3) Is our prepared plot considered a raised bed?

I read that this is not good for the drainfield and am wondering what affects it could have on the functioning of the system? Also, is there anything we could do, since the plot is already prepared, to help combat any negative affects? PLEASE HELP! We worked so hard on this and will be soon ready to plant but don't want to endanger our family with contaminated foods!

Reply: variation in site conditions may cause risk of actual sewage contamination of vegetables and possibly higher-up fruit crops to risk to vary accordingly

Tanya,

Good question but not one we can hazard by text exchange and no real data; For example, some creeks will seasonally contain quit high levels of local septic field runoff and more seriously, in communities where there are many older, crowded, or under-designed, or under-maintained septic systems, a high level of sewage effluent may regularly be discharged to the surface or to nearby creeks and streams. So unforutnately there's no simple Yes or No answer that in my opinion would be reliable.

I think this is a good question to take to your health department.

Summer,

Thanks for the interesting question Summer. I am torn between wanting to be helpful and wanting to be careful not to bet your health on a situation that I cannot really know much about by just exchangin text messages.

I agree that you understand the different sanitation concerns or contamination pathways: bacteria entering a plant through the soil vs. contaminant splash-up. Generally one would imagine that above-ground crops have their greater risk from sewage splash-up.

But interestingly even among fruit trees planted over questionable soils, the rate of infection appears to vary by species (though I suspec there may have been other factors at work). See Sipahioglu (1999) in the citations above.

More examples of variation in site conditions that may cause sewage contamination risk to vary as well

• Drainfield-grown food crops may be safe today but maybe not tomorrow or next year: You may think that there is no wastewater splash-up. Suppose you're right - right now.
  
  Generally building and health codes are written not just for the special case of people who are very careful and pay close attention to hazards, but for the more general real-world case that includes "what goes wrong" including
  • area flooding
  • heavy rains, snow melt, and saturated soils
  • changes in soil moisture, wind, nearby surface runoff
  • changes in the area water table height, particularly an increase in the seasaonal high water table
  • changes in septic system maintenance - a new owner forgets about pumping the septic tank or has a large family who make much heavier use of the system
  • changes in what is being flushed down drains: chemicals, medications (see the June 2012 remarks from Anonymous about chemotherapy chemicals)
  • changes in soakaway bed pipe condition: equpment damage, soil added or taken away, changes in surface drainage from nearby properties, even normal drainfield clogging that eventually occurs with age and bio-film formation
  • temporary septic system overloading or new drainfield failures or similar events all of which can contaminate surface crops.
    
    So in other words, you might be ok but not risk-free. If you are inclined take a look into some of the research documents we've cited on this.
• Further, you want to be sure not to drive any kind of heavy equipment (heavier than a homeowner's type lawn mower) over a septic drainfield as doing so risks damaging the field.
• Next, adding a cover that interferes with evaporation or to be fancy transpiration interferes with proper soakaway bed functioning and increases the failure risk.
• Adding additional feet of fill also interferes with drainfield function by reducing the oxygen available to soil bacteria thus reducing the level of treatment. That's why deep drainfields in areas of deep freezing soil are really never really treating effluent anyway.
• Further, any crops that may send deep roots may end up seeking and invading and clogging the drainfield lines.

Question: does greywater contaminate fruits and vegetables planted over the septic area ?

AUTHOR:B. Sturgis (no email)
COMMENT:Lemon tree planted over greywater, washing machine only, septic area. Will lemons be safe to eat?

Reader Question: How can I get my vegetable and fruit produce professionally tested to ascertain contamination from sewage pathogens?

(Apr 28, 2014) Mark said:
How can I get my vegetable and fruit produce professionally tested to ascertain contamination from sewage pathogens?

Reply:

Mark a microbiology test lab, the same folks who do water testing, sewage contamination testing, can test other materials for pathogens. Be sure to discuss with local labs in your area just what is their normal scope of work and expertise. Some labs drastically limit their practice.

(Apr 29, 2014) Mark said:
Thanks so much -- that was very helpful.

Reply:

Glad to assist, Mark and your question is helpful to me as well.

If you want to better understand the concerns around pathogens found in fruits & vegetables I found the following article quite pertinent.

• Leff, Jonathan W., and Noah Fierer. "Bacterial communities associated with the surfaces of fresh fruits and vegetables." PloS one 8, no. 3 (2013): e59310.
  Abstract:
  Fresh fruits and vegetables can harbor large and diverse populations of bacteria. However, most of the work on produce-associated bacteria has focused on a relatively small number of pathogenic bacteria and, as a result, we know far less about the overall diversity and composition of those bacterial communities found on produce and how the structure of these communities varies across produce types.
  
  Moreover, we lack a comprehensive view of the potential effects of differing farming practices on the bacterial communities to which consumers are exposed. We addressed these knowledge gaps by assessing bacterial community structure on conventional and organic analogs of eleven store-bought produce types using a culture-independent approach, 16 S rRNA gene pyrosequencing.
  
  Our results demonstrated that the fruits and vegetables harbored diverse bacterial communities, and the communities on each produce type were significantly distinct from one another. However, certain produce types (i.e., sprouts, spinach, lettuce, tomatoes, peppers, and strawberries) tended to share more similar communities as they all had high relative abundances of taxa belonging to the family Enterobacteriaceae when compared to the other produce types (i.e., apples, peaches, grapes, and mushrooms) which were dominated by taxa belonging to the Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria phyla.
  
  Although potentially driven by factors other than farming practice, we also observed significant differences in community composition between conventional and organic analogs within produce types. These differences were often attributable to distinctions in the relative abundances of Enterobacteriaceae taxa, which were generally less abundant in organically-grown produce.
  
  Taken together, our results suggest that humans are exposed to substantially different bacteria depending on the types of fresh produce they consume with differences between conventionally and organically farmed varieties contributing to this variation.

My point is that when we ask a lab to test for pathogenic contamination of fruits and vegetables we need to

1. ignore the folks who argue that such foodstuffs are not at risk and so testing is always unnecessary

2. ask the lab what they will test-for, as we might need to look for different pathogens on different foods. I worry that some prior research, as I've found in the area of mold contamination, seriously misreports the presence or absence of hazards because the investigator didn't look thoroughly or used an unreliable test method.

Like bird watching, how do you spot a Quetzal? Well you have to look where they live (in certain areas of Costa Rica) and it helps to know what they eat (little avocados) and when they will be there eating (early morning).

Another bird watcher might say there are no Quetzals there, even looking in the same spot, but at the wrong time of day.

...

Continue reading  at SEWAGE CONTAMINANTS in FRUIT / VEGETABLES or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see

• BACTERIAL PATHOGENS in FRUIT & VEGETABLES - research citations on sewage contaminants in fruits & vegetables
• VEGETABLE or PRODUCE DISINFECTION
• SEWAGE CONTAMINANTS in FRUIT / VEGETABLES
• SEWAGE NITROGEN CONTAMINANTS
• SEWAGE PATHOGENS in SEPTIC SLUDGE for a list and discussion of of the common pathogens and other contaminants in residential sewage

Suggested citation for this web page

SEWAGE CONTAMINATION of FRUIT VEGETABLES, FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to SEPTIC SYSTEMS

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