Most people think hard-to-treat germs are something you only hear about in hospitals. But these pathogens don’t stay in one place — they’re everywhere, and you don’t need to be in a medical setting to come across them.
Germs live on food, surfaces, pets, and throughout the environment. As they grow more virulent and harder to control, researchers now look beyond hospitals to understand where they come from and how they spread.
One of the most common sources of exposure today is the water supply. And it’s not only drinking water, but all the water that moves through our communities, including treated wastewater. In many places, it is dumped into rivers and reused on farms for irrigation, which means it comes into contact with the crops we eat. Most people never think about that connection, but it’s becoming an important part of the public health conversation.
Treated Wastewater May Be Part of the Antibiotic-Resistance Problem
As water shortages intensify around the world, recycled wastewater has become a widely used irrigation source, supporting over 20 million hectares of farmland across 50 countries.1 Yet even when treated, it introduces foodborne pathogens onto the food we eat. Considering this, a study published in Frontiers in Microbiology2 investigated how varying treatment levels affect the movement of contaminants from irrigation water to crops.3
• Framework of the analysis — Researchers grew three sets of 936 lettuce plantlets and irrigated each group with a different type of water to observe how each one affected the presence of bacteria and antibiotic resistance genes (ARGs) on the leaves.
The water was sourced from a municipal wastewater treatment plant (WWTP) that employed standard multi-stage treatment processes. Here’s a breakdown of each type of treated wastewater used in the study:
◦ Potable water — Drinking-quality water with very low levels of germs and contaminants.
◦ Secondary-treated wastewater — Water that has gone through basic biological treatment at the WWTP, including aeration, solids removal, and sludge processing. While cleaner than raw sewage, it may still carry fecal bacteria and ARGs.
◦ Tertiary-treated wastewater — Water that receives additional cleaning through sand filtration and ultraviolet-C (UVC) light, a short-wavelength UV light that damages and inactivates microbes.
• Bacteria and genes were tracked across both water and lettuce samples — The researchers tested for the presence of Escherichia coli (E. coli), a common fecal bacterium, and extended-spectrum beta-lactamases (ESBL)-producing E. coli, a drug-resistant strain capable of deactivating antibiotics. They also measured four ARGs known to help bacteria break down various types of antibiotics and provide resistance.
• Secondary-treated wastewater was the most contaminated — Tap water and tertiary-treated water showed no detectable E. coli or drug-resistant strains. In contrast, secondary-treated wastewater consistently tested positive for both bacteria and resistance genes at much higher levels.
• What researchers discovered in the lettuce — Samples irrigated with secondary-treated water had varied contamination rates:
â—¦ 94% of these plants contained E. coli
â—¦ 61% carried the drug-resistant ESBL-producing strain
â—¦ Only 33% of plants irrigated with tap water or tertiary-treated water contained E. coli, and none had the drug-resistant strain
• Some resistance genes were present even before irrigation — Some ARGs were present in seedlings before the experiment even started, suggesting that seeds or starter soil might already carry resistance. After irrigation, ARG levels increased most noticeably in the secondary-treated group.
Tertiary-treated water caused only a slight increase. Interestingly, only about 4% to 6% of resistance genes in the water ended up in the lettuce, suggesting limited transfer under controlled conditions, but still enough to matter for crops eaten raw.
In future studies, it would be great to explore how widely these results can be applied, understand why some seedlings already have ARGs, and see how farming practices and environmental factors influence the spread of antibiotic resistance in fresh produce.
How Hospital Waste and Urban Sewage Contributes to the Spread of Drug Resistance
If treated irrigation water poses risks, what about the rest of our wastewater? A second review, published in Tropical Medicine and Infectious Disease,4 broadens the lens and examines how hospital waste, urban sewage, and even mass-gathering events contribute to the global spread of drug-resistant bacteria.
The authors reviewed 63 studies spanning a decade, analyzing wastewater from hospitals, municipal systems, rivers, and religious events like the Hajj in Saudi Arabia and Kumbh Mela in India. All studies used genetic testing to detect ARGs and antimicrobial-resistant bacteria (ARBs) in real-world environments.
• Resistance genes and bacteria were everywhere — Researchers found ARGs and drug-resistant bacteria in untreated sewage, treated effluent, downstream rivers, and even water sources labeled safe for use. The strains included Klebsiella, Salmonella, Acinetobacter, and Enterococcus, some of which were resistant to last-line antibiotics such as carbapenems and vancomycin.
• Treatment doesn’t always remove resistance — Standard wastewater treatment can lower the number of bacteria, but it often fails to eliminate resistance genes. These survive the process and move into rivers and soil.
• Hospitals and pharmaceutical plants are major hotspots — Hospital sewage contained some of the strongest resistance traits, including carbapenem-resistant and ESBL-producing strains. Pharmaceutical wastewater held high levels of clinically important resistance genes. In low-income regions, this waste often enters the environment with little or no treatment.
• Large religious gatherings worsen the issue — During events like the Hajj and Kumbh Mela, wastewater tanks and nearby rivers showed sharp spikes in resistant bacteria and resistance genes. Pilgrims at the Hajj were found to acquire resistant strains and may unknowingly carry them home. At Kumbh Mela, mass bathing caused dramatic increases in river contamination.
• Gene sharing makes resistance more dangerous — Resistance doesn’t spread only through infection. Bacteria can trade resistance genes using plasmids — small loops of DNA they pass between each other — and other mobile elements. This allows even harmless microbes in wastewater to become resistant to antibiotics over time.
• Urgent upgrades are needed — The authors emphasized the importance of investing in modern treatment technologies such as membrane filtration, ozonation, and UV treatment. They also stress the need for closer monitoring in high-risk settings, especially hospitals and large-scale gatherings.
The findings from the wastewater-and-lettuce study highlight a broader point: Antibiotic resistance can enter the food system through multiple pathways; irrigation water is just one example. Another major and overlooked route is fertilizer made from sewage sludge, which is applied to millions of acres of farmland in the U.S. and abroad.
How Biosolids and Pesticides Fuel Antibiotic Resistance
When you hear the word biosolids, it almost sounds eco-friendly, but it is really the industry’s polite term for sewage sludge used as fertilizer. It’s made from everything that’s washed down household drains, hospital pipes, and industrial facilities. And when it’s used on farmlands, it brings more than just nutrients. Here’s what researchers and regulators found out:
• Biosolids contain a wild mix of contaminants — Sewage sludge isn’t just decomposed organic waste. It also holds antibiotics, pathogens, industrial chemicals, pharmaceuticals, hormones, flame retardants, and per- and polyfluoroalkyl substances (PFAS) chemicals — basically anything that goes down the drain.
In 2018, the U.S. Office of Inspector General5 reported that biosolids contained hundreds of pollutants, many of which had incomplete or missing safety data.
• Nutrient overload from biosolids also harms the environment — Because biosolids are rich in nitrogen, applying them in large amounts can contribute to algae blooms in coastal waters. These reduce oxygen in the water, kill fish and other wildlife, and disrupt entire ecosystems.
• Biosolids help spread antibiotic resistance — Human waste already contains antibiotics, antibiotic-resistant bacteria, and resistance genes from both medical use and everyday drug exposure. When this waste mixes with industrial and hospital contaminants and is then applied to soil, it creates another pathway for antibiotic-resistant microbes to spread.
Biosolids aren’t the only issue. Researchers have discovered that numerous common chemicals affect how bacteria adapt, survive, and become more resistant. To learn more about the hazards of herbicides, read “Pesticides Compound Antibiotic Resistance.”
• Lots of chemicals, little testing — Around 8 million chemicals are manufactured today, and about 3,000 of them are produced in very large amounts each year. Yet most of these chemicals are not assessed by the U.S. Environmental Protection Agency (EPA) to determine whether they may contribute to antibiotic resistance.6
• Why researchers say this gap matters — Scientists argue that looking only at antibiotic use overlooks other factors that push microbes to adapt. They point to non-antibiotic chemicals that can change bacterial behavior, gene expression, and biofilm formation — factors that can blunt antibiotic effectiveness. As one paper in PeerJ put it:7
“Evidence that antibiotic resistance evolution is influenced by exposure of bacteria to a wide range of substances may require us to make changes in how we manage both antibiotics and other manufactured and widely distributed chemical products …
As our results show, complex effects of exposures to nontherapeutic chemicals may undermine strategies to preserve the effectiveness of antibiotics through altering just their use. To our knowledge, there has been no attempt to systematically test common chemicals to which pathogenic bacteria are chronically exposed for effects on antibiotic resistance.”
Given that resistance genes now permeate our soil, water, and food supply, researchers are asking a different question: Can anything we eat actually help us fight back? Emerging evidence suggests certain vegetables might do exactly that.
How Crucifers Help Combat Antibiotic Resistance
Cruciferous vegetables are known for their many health benefits, but they also play a surprising role in fighting antibiotic resistance. A study published in Pharmaceutics8 indicates that compounds found in these crops help reduce bacterial virulence and enhance the efficacy of antibiotics.
• Cruciferous veggies offer potent health benefits — Vegetables such as broccoli, kale, cabbage, Brussels sprouts, cauliflower, and collards provide sulforaphane, a sulfur-rich compound known for detox and cellular protection, along with indole-3-carbinol (I3C),9 which supports hormone balance and immune health.
• When digested, I3C converts into Diindolylmethane (DIM) — This is a potent antimicrobial agent that boosts immune function. Scientists now believe DIM may help reduce antibiotic resistance by interfering with the defense mechanisms of antibiotic-resistant bacteria.10
• DIM blocks biofilm formation in multiple superbugs — In lab studies, DIM reduced biofilm growth in four dangerous bacteria by up to 80%.11
When paired with the antibiotic tobramycin, DIM cuts biofilm formation by 94%. Researchers caution against daily DIM supplementation because it can affect hormone metabolism, but suggest it could be helpful during active infections. Drug-resistant species showed the strongest response.
When DIM was tested against Pseudomonas aeruginosa and Acinetobacter baumannii, which resist many antibiotics, biofilm formation dropped by 65% to 70%. Biofilms act as protective shields that block antibiotics, so this reduction suggests DIM could help antibiotics work against persistent infections
Choose Healthy, Organic Foods Whenever Possible
Choosing organic foods are a practical way to reduce everyday exposure that may affect long-term health. While organic produce generally costs higher than conventionally grown ones, it offers meaningful protection like:12
• Less exposure to antibiotics from animal products — Organic meat, dairy, and eggs come from animals raised without routine antibiotics or growth hormones. This can help reduce your indirect exposure to antibiotics, which may otherwise contribute to resistance and gut microbiome imbalance.
• Lower exposure to pesticides and insecticides — Organic produce is grown without synthetic pesticides and insecticides, which reduces your overall chemical load.
• Cleaner soil and water practices — Organic farming prohibits sewage sludge and emphasizes soil and water protection. That means less chemical runoff into rivers and groundwater — an important consideration as wastewater and agricultural pollution increasingly affect food systems.
• Making wiser purchases — Consider buying organic fruits and vegetables you eat raw, while choosing conventional varieties for those you cook, as many common cooking methods reduce, but do not completely eliminate, pesticide residues on food. This can lower your pesticide exposure and still fit within a realistic budget.
More Ways to Reduce Your Risk of Antibiotic Resistance
Antibiotic resistance isn’t unavoidable. Small, everyday decisions can reduce your exposure and support your long-term health, especially in areas where antibiotics are frequently used. If you’ve taken antibiotics before, it’s advisable to be proactive in reducing your overall exposure and to use alternatives when suitable. Here are practical steps to stay ahead:
• Avoid antibiotics unless truly needed — Antibiotics shouldn’t be your automatic first response. Most minor infections resolve on their own, and antibiotics don’t work for viral illnesses like colds or the flu. Using them “just in case” contributes to resistance and reduces their effectiveness when needed.
• Include probiotic-rich foods in your routine — Traditional fermented foods such as sauerkraut, kimchi, yogurt, and kefir contain naturally occurring probiotics that support overall resilience. Making them a regular part of your diet helps maintain a balanced microbial environment in the body, especially after illness or stress.
• Reduce your intake of linoleic acid (LA) — LA is found in high amounts in vegetable oils, many nuts, and ultraprocessed foods. Excessive LA contributes to systemic inflammation and can increase susceptibility to the adverse effects of repeated antibiotic use.
Lessen your exposure to seed oils by replacing them with healthier fats such as beef tallow, grass fed butter, coconut oil, or ghee. Aim to keep your daily LA intake below 5 grams and ideally closer to 2 grams. You can also sign up for the upcoming Mercola Health Coach app, which includes the Seed Oil Sleuth — a feature that tracks your LA intake down to a tenth of a gram.
• Prioritize foods that help maintain balance — Certain foods naturally support internal balance and resilience. Options like apples (with the skin), onions, and asparagus contain fiber and plant compounds that your body uses to maintain stability during periods when you’re more susceptible to infection.
• Explore natural antimicrobials before turning to pharmaceuticals — Some natural substances can help your body respond to mild bacterial challenges without resorting to prescription antibiotics. Manuka honey, garlic, ginger, and thyme essential oil all have documented antimicrobial properties. For deeper guidance, see “Natural Options to Try Before Taking Antibiotics.”
Your health isn’t one-size-fits-all, and it shouldn’t be treated that way. What works for someone else might not work for you, and that’s exactly why you deserve real options. Whether it’s changing what you eat, using targeted natural compounds, or rethinking when you truly need antibiotics, you should have the freedom to choose what supports your well-being.
Frequently Asked Questions (FAQs) About Treated Water and Antibiotic Resistance
Q: What did the lettuce irrigation study reveal about treated wastewater?
A: The Frontiers in Microbiology study showed that crops irrigated with secondary-treated wastewater were more likely to carry fecal bacteria and antibiotic-resistance genes, while tertiary-treated water performed similarly to potable water.
Q: What broader risks did the wastewater review uncover?
A: The review in Tropical Medicine and Infectious Disease found that antibiotic resistance genes and drug-resistant bacteria show up not just on farms, but in hospital waste, rivers, and even water used at large public gatherings.
Q: Why does wastewater treatment level matter so much?
A: Basic treatment removes visible waste but often leaves resistance genes intact. Advanced steps like filtration and UV treatment are far more effective at reducing microbial risks before water is reused or released.
Q: How do biosolids and chemicals worsen the resistance problem?
A: Sewage sludge and common chemicals can expose soil bacteria to antibiotics and pollutants, creating conditions that help resistance develop and persist in the environment.
Q: What can I do to lower my personal risk?
A: Choosing organic foods, eating fermented and fiber-rich foods, limiting unnecessary antibiotics, and supporting gut health can help reduce your exposure and strengthen natural defenses.
