Irrigating Your Vegetables With Treated Sewage Water? Still Not a Good Idea if You Are Concerned About E. Coli


Posted on 05 January 2007

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By Frank Pecarich
Retired Soil Scientist

Well, the season for growing leafy vegetables in Salinas Valley is mostly over until the spring. According to the history of the past 10 years, we will again see an outbreak of deadly E. coli 0157H: 7 sometime this coming summer of fall. We can safely say that because nothing of substance has changed since the furor over the 3 deaths and over 200 sickened citizens in the Fall of 2006.

According to the U.S. Centers for Disease Control and Prevention, Americans suffer 6.3 million illnesses per month, 27,000 people are hospitalized each month, and 416 die each month from something they ate.

We are being told that future attention to pathogen prevention in Monterey County will be mainly focused on animal grazing areas being too close to cultivated fields. That is because the primary “host” animal for E. coli 0157H: 7 is an animal like a cow. What isn’t appreciated is that when the pathogen E. coli 0147H:7 is ingested by a human, we humans are the “host” for that organism until it passes from our body.

In this last outbreak, there were 200 such humans who were harboring E. coli 0157H:7 plus all the others who were infected but did not report the disease. It has been estimated by pathologists and medical specialists that for every reported incident of E. coli 0157H:7 there are 9 more that are not reported. Those people then aided in the pathogen getting to another source of contamination, the sewer and ultimately, the local waste water treatment system. In the Monterey County incident, there may well be 2,000 people out there that were adversely impacted, not just the 200 as oft reported.

How Does It Get From Cows to Humans?

In addition to humans who are sick with drug resistant pathogens such as E. coli 0157H:7 passing their contaminated feces into the sewage system from their homes and the hospitals, blood and fecal material are flushed away from animal slaughter houses that can be contaminated with pathogens, like E. coli 0157H:7. Add to that source, the hospital treatment centers that have their sewage flushed into the local waste water treatment facility and you have a deadly toxic “Witch’s caldron” environment in the local sewer treatment system.

To further illustrate this problem, a research study entitled, “Hospital effluent: A source of multiple drug-resistant bacteria” was done by V. Chitnis, D. Chitnis, S. Patil and Ravi Kant. This project was carried out to study the spread of “multiple drug-resistant” (MDR) bacteria from hospital effluent to the municipal sewage system. The study showed that MDR bacteria population in hospital sewage effluents ranged from 0.58 to 40% for ten hospitals studied while it was less than 0.00002 to 0.025% for sewage samples from the residential areas. In other words, there were 1000+ times more drug resistant pathogens in the hospital sewage compared to the average residence.

Further, the study showed that MDR bacteria carried simultaneous resistance for most of the commonly used antibiotics. It illustrates that not only do drug resistant pathogens pass from hospitals into the sewage system, these multi-resistant strains of bacteria are becoming totally invulnerable to treatment.

Antibiotic Resistance Spreads

Antibiotic resistant genes spread readily between human beings, and from bacteria inhabiting the gut of farm animals to those in human beings. Antibiotic-resistant strains of pathogens have been present in many hospitals for years. In the USA, up to 60% of hospital-acquired infections are antibiotic resistant according to the World Health Organization

In 1998, Thomas A. Ternes , a chemist with the municipal water research laboratory in Wiesbaden, Germany realized that tons of medicines are prescribed each year in
Germany, "but nobody knows what happens to those compounds after they are excreted." So a few years ago he launched a water-monitoring project to look for drugs in sewage, treated water, and rivers.

He expected to find a just a few medicinal compounds. Instead, he detected 30 of the 60 common pharmaceuticals for which he tested. These included lipid-lowering drugs, antibiotics, analgesics, antiseptics, and beta-blocker heart drugs. He has even found residues of drugs to control epilepsy and ones that serve as contrast agents for diagnostic X rays.

Ternes detected concentrations of these drugs in both raw sewage and the water leaving treatment plants. "We also found these compounds in nearly all streams and rivers in Germany," he says. The highest concentrations tended to show up in the smallest rivers, where 50 percent of the water could be sewage treatment effluent.

Sewage Treatment Does Not Kill All Pathogens

It has been repeatedly proven scientifically and most recently in a University of Minnesota study reported in May, 2006, that certain antibiotic resistant pathogens such as E. coli 0157H:7 can pass through the tertiary treatment process and come out in the water released into the environment. They are then ready to infect their new host either human or animal.

Actually, many types of bacteria, virus, and other pathogens pass through sewer treatment works into the surrounding environment.

Because pathogens that might otherwise seldom come together are crowded together during sewer treatment, the opportunity for genetic exchange is also greatly enhanced. The results can be a sort of “super germ” totally resistant to antibiotics just as is E. coli 0157H:7 Thus the sewage treatment environment gives potential for highly accelerated genetic exchange to this variety of pathogens and non-pathogens that can continue to exist once released to the environment.

Back to Monterey County

As I have explained in earlier articles, Monterey County in California has built a sewage recycling system that provides treated sewage water to irrigate 12,000 acres of prime vegetable cropland in the vicinity of Salinas and Castroville, California. The sewage wastewater reclamation plant was completed in 1997 and began delivering reclaimed water (tertiary treated) sewage water for food crop irrigation in 1998. They call this system the Castroville Sea Water Intrusion Project (CSIP)

In the case of the CSIP project in Monterey County, the pathogens are free to rest and lodge on the leaf surface because most of the irrigation used for these spinach and lettuce crops is by sprinkler rather than by furrow. It is reported that water is only tested as it leaves the treatment plant but not at the point of delivery in the field. The waters that are sprayed should be tested at the sprinkler heads in the irrigated fields and there has been no indication that this is done as a matter of practice by growers.

The 45 mile long CSIP pipeline is a potential germ reservoir environment where “biofilms” of pathogens can collect at turns, bends and imperfections in the pipeline. These pathogen colonies can then easily be dislocated, jarred and discharged with the mechanical shock of the high power pumps being turned on. Those toxic pathogens then are released into the sprinkler spray to eventually rest and lodge on the plant leaf. If there are leaks in the pipeline – a common occurrence -- materials from the outside can reenter the pipes, thus contaminating the water.

The Monterey County sewage treatment plant must meet the minimal standards under Title 22 of the California code. But it is reported that there have also been “upsets” within the treatment plant where it was unable to comply with those standards.

Further, there is the possibility that when the sewage treatment plant did fail to meet the minimal standards and thus discharged substandard and potentially contaminated water (something that is not a rare event for this plant), pathogens could escape. Once pathogens are within the pipe, whether from a hydraulic “burp” at the plant or from a hydro-hammer pumping effect at a pipeline crack, it would be possible for biofilms to develop. These biofilms defy standard disinfection techniques and hence become permanent shedders of pathogens.

Further the laboratory tests required by Title 22 do not consider many of the newly emerging infectious diseases and completely miss pathogens that have shifted into protective states – “stealth pathogens”. One of these states of protection is the “viable but non-culturable” state (VBNC). It has been well demonstrated that while in the VBNC state, these microbes are invisible to the standard lab tests required under Title 22.

Monterey County officials would try to have you believe that their sewage effluent does not contain pathogens. However, Monterey County in a proposal to build another phase of the CSIP confesses in their written material that their recycled water indeed contains pathogens. This new phase they propose to build will directly inject recycled sewage water into the groundwater aquifers in an additional attempt to forestall more seawater intrusion into their water aquifers. In a section entitled “Water Quality Implications” they state:

“In general, there is a concern that storage of recycled water in the groundwater aquifer would lead to long-term water quality degradation from nitrogen (nitrate) and other constituents of recycled water such as pathogens and trace organic compounds. Such degradation could cause a portion of the aquifer to become unusable for domestic purposes, including adjacent areas of the aquifer outside the area of direct injection/extraction.” [emphasis added]

They conclude by saying:

“Consequently, it would be necessary to contain and control the injected recycled water to a specific area, and to control migration, so that the water in the aquifer in the vicinity of the subsurface storage facility is not adversely affected.”

On November 6th, we read that two major players in the recycled (treated sewage effluent) water business were sponsoring a research study. American Water, the private water utility company, has joined forces with the WateReuse Foundation to conduct a research project on the biology of recycled water.

The 30-month long, $500,000 project will “examine the data on how microbial re-growth in recycled water distribution systems alters effluent microbial water quality and how to control this germ re-growth”, the release said.

These same organizations have for years been telling the public that recycled/reclaimed tertiary treated sewage effluent was OK to spray on our leafy green vegetables such as lettuce and spinach. Now they want to spend $500,000 to find out how to control microbial germ (E.coli 0157H:7) re-growth? They now want to study something that they said didn’t exist.

Currently, the apparent thrust by the food production and wastewater industry is to blame cattle or wild pigs for the contamination of spinach in the Monterey County. I believe that this is an attempt to deflect attention away from sewage derived materials used to irrigate vegetable crops. It appears to be a carefully orchestrated effort by the wastewater industry to shift focus away from an important and highly suspect area for causing food related illness.

The upshot of all this is that a serious and publicly transparent review of this problem as well as the underlying standards and regulatory framework is highly warranted. Our health depends on it.


Frank Pecarich retired from the Washington, D.C. headquarters of the US Bureau of Reclamation in 1987. During his 26 year federal career he worked as a soil scientist with the USDA on the now- published Soil Survey for Monterey County. He lives in Ventura County.

Related articles that have been published by the California Progress Report by Mr. Pecarich include:
E. coli: Why Monterey County Made a Poor Decision on the Type of Water to Use for Irrigation of Their Croplands

E. coli: Is There a Cover-up of Poor Decisions on the Type of Water Used for Irrigation of Croplands in the Salinas Valley?

Why Do We Abandon Science in Favor of PR? Orange County Follies

Monterey Cover-up on Cause of Spinach and Lettuce Contamination?
Deadly Pathogens and Science vs. PR and Politics: Spinach in Monterey County

Arnold Schwarzenegger and the “I Heart Spinach” Program or Has the “Terminator” Become the “Germ-a-nator”?