Atrazine is a widely used herbicide that can enter rivers, streams, and groundwater after application to agricultural land.
Because atrazine is used extensively on crops such as corn, sorghum, and sugarcane, it is monitored as a drinking-water contaminant in the United States.
The U.S. Environmental Protection Agency has established a federal Maximum Contaminant Level (MCL) for atrazine in public drinking water of 0.003 mg/L, or 3 parts per billion (ppb).
Quick answer: Atrazine can reach water through agricultural runoff and movement through soil. Public water systems must meet EPA's 3 ppb drinking-water standard. If you use a private well in an agricultural area, testing is the most reliable way to determine whether atrazine is present. Granular activated carbon and some reverse-osmosis systems can reduce atrazine when the finished system has been specifically tested or certified for that purpose.
In This Guide
- What Is Atrazine?
- How Atrazine Gets Into Water
- EPA Drinking-Water Limit
- Potential Health Effects
- Atrazine and Cancer
- Pregnancy and Reproductive Research
- How to Test for Atrazine
- How Atrazine Can Be Reduced
- Activated Carbon
- Reverse Osmosis
- Public Water Systems
- Private Wells
- Frequently Asked Questions
What Is Atrazine?
Atrazine is a synthetic herbicide in the triazine chemical family.
It is used primarily to control annual grasses and broadleaf weeds before or after they emerge.
EPA-registered uses include crops such as:
- Field corn
- Sweet corn
- Sorghum
- Sugarcane
- Wheat
- Macadamia nuts
- Guava
Atrazine is also registered for some non-agricultural applications.
It works in susceptible plants primarily by interfering with photosynthesis.
Atrazine does not occur naturally. It is manufactured for use as a herbicide and can enter the environment during and after application.
How Does Atrazine Get Into Drinking-Water Sources?
Atrazine applied to soil or crops does not necessarily stay where it is sprayed.
Depending on rainfall, irrigation, soil, geology, and application conditions, it may move through:
- Surface runoff
- Drainage water
- Soil
- Groundwater
Surface-water concentrations can sometimes increase after agricultural application followed by rainfall.
Groundwater contamination can occur when atrazine or its breakdown products move downward through soil into an aquifer.
This makes agricultural regions an important focus for monitoring.
For broader context, see our Pesticides and Drinking Water Guide.
What Is the EPA Limit for Atrazine in Drinking Water?
EPA regulates atrazine under the National Primary Drinking Water Regulations.
| Measure | Atrazine Level | What It Means |
|---|---|---|
| MCLG | 0.003 mg/L | 3 parts per billion |
| MCL | 0.003 mg/L | 3 parts per billion; enforceable public drinking-water standard |
The Maximum Contaminant Level Goal (MCLG) is a health-based goal.
The Maximum Contaminant Level (MCL) is the enforceable limit that applies to regulated public water systems.
3 ppb does not mean atrazine becomes instantly harmful at 3.1 ppb. Drinking-water standards are regulatory thresholds established based on toxicology, exposure assumptions, safety considerations, treatment feasibility, and other factors.
What Are the Potential Health Effects of Atrazine?
The health effects of atrazine depend on:
- Dose
- Duration of exposure
- Route of exposure
- Age
- Individual health factors
- Other chemical exposures
EPA's drinking-water regulations identify cardiovascular-system and reproductive effects as potential concerns associated with long-term exposure above the drinking-water standard.
Animal studies have identified effects on reproductive and neuroendocrine function at sufficiently high exposures.
Human epidemiological studies have also investigated atrazine in relation to:
- Pregnancy outcomes
- Reproductive effects
- Hormonal changes
- Selected cancers
However, associations observed in epidemiological studies do not necessarily establish that atrazine directly caused the reported outcome.
The old version of this article overstated the human evidence. Animal findings involving hormones or reproduction should not automatically be presented as proven effects in people drinking water at typical environmental concentrations.
Does Atrazine Cause Cancer?
The evidence is more complicated than many older articles suggest.
Some older animal studies reported increased mammary tumor incidence in a particular strain of female rats.
However, EPA concluded that the mechanism responsible for those tumors in that rat strain was unlikely to operate the same way in humans.
EPA has therefore classified atrazine as not likely to be carcinogenic to humans.
Human epidemiological research continues to examine possible associations with particular cancers, but those studies have not established that atrazine in drinking water causes breast or prostate cancer.
Bottom line: It is not accurate to state that atrazine is a proven human carcinogen or that drinking atrazine-contaminated water is known to cause breast or prostate cancer.
What About Pregnancy, Birth Outcomes, and Reproduction?
Atrazine's possible effects on reproduction and development have received considerable scientific attention.
Animal studies have reported effects involving:
- Reproductive hormone regulation
- Puberty timing
- Reproductive cycles
- Fetal growth or development at sufficiently high exposures
Some observational studies in humans have reported associations between maternal atrazine exposure and selected pregnancy or birth outcomes.
However, the evidence is not strong enough to state that drinking atrazine at environmental levels directly causes:
- Miscarriage
- Infertility
- Specific birth defects
- Diabetes in children
- Cardiovascular disease in children
These outcomes can have many causes, and observational studies can be affected by other environmental and individual factors.
EPA continues to reevaluate atrazine as new scientific evidence becomes available. Pesticide registration review is an ongoing process rather than a one-time determination.
Is Atrazine an Endocrine Disruptor?
Atrazine has affected neuroendocrine and reproductive signaling in animal studies.
For example, research in rodents has examined effects involving:
- Luteinizing hormone signaling
- Puberty timing
- Ovarian cycles
- Male reproductive systems
These findings are important for toxicological assessment.
However, they do not justify the simplified claim that atrazine "converts testosterone to estrogen" in people who drink exposed water.
Human endocrine effects at environmental exposure levels remain an area requiring careful interpretation.
Who Is Most Likely to Be Exposed to Atrazine?
Potential exposure can occur through several pathways.
Agricultural Workers
People who mix, load, or apply atrazine may have more direct occupational exposure than the general population.
People Living Near Agricultural Areas
Atrazine can occur in nearby surface water or groundwater, particularly where the herbicide is heavily used, and environmental conditions favor runoff or leaching.
Private-Well Households
Unlike public water systems, private wells are generally not routinely monitored by a water utility.
That makes household testing more important when local agricultural activity raises concerns.
How Can You Tell Whether Atrazine Is in Your Water?
You cannot reliably identify atrazine by looking at, smelling, or tasting the water.
Laboratory testing is required.
If You Use Public Water
Start with your utility's annual Consumer Confidence Report.
Public water systems monitor regulated contaminants in accordance with applicable federal and state requirements.
If You Use a Private Well
Consider contacting:
- Your state drinking-water or environmental agency
- Your county health department
- A cooperative extension office
- An accredited drinking-water laboratory
Ask whether atrazine or a broader pesticide panel is appropriate for your location.
See our Well Water Testing & Treatment Guide.
Do not assume a general home test strip can accurately measure atrazine at drinking-water concentrations. Atrazine is typically measured using specialized laboratory analytical methods.
How Can Atrazine Be Reduced in Drinking Water?
Treatment should be selected based on the actual atrazine concentration, water chemistry, flow requirements, and the intended treatment point.
Two commonly used approaches are:
- Activated-carbon treatment
- Reverse osmosis
The most important consideration is performance of the finished treatment system.
Granular Activated Carbon and Atrazine
Granular activated carbon is widely used to adsorb many organic contaminants in drinking water, including atrazine.
Performance depends on factors such as:
- Carbon type
- Amount of carbon
- Contact time
- Water chemistry
- Atrazine concentration
- Filter age
- Flow rate
As carbon becomes exhausted, its contaminant-reduction capacity declines.
Look for atrazine-specific performance. NSF's certification database includes drinking-water treatment products with an Atrazine Reduction claim under NSF/ANSI 53. The fact that a filter contains activated carbon alone does not prove that the finished product is certified or tested for atrazine.
Can Reverse Osmosis Reduce Atrazine?
Some reverse-osmosis systems can reduce atrazine and other organic contaminants as part of a multistage treatment system.
Household RO systems often combine:
- Sediment filtration
- Activated-carbon prefiltration
- An RO membrane
- Post-filtration
As with carbon filtration, performance should be verified for the specific model.
For a comparison of RO, activated carbon, ion exchange, gravity filtration, and other technologies, see our Types of Drinking Water Filtration Systems Guide.
How Do Public Water Systems Address Atrazine?
Public water systems regulated under the Safe Drinking Water Act must comply with the federal MCL for atrazine.
Where treatment is needed, utilities can use appropriate technologies, such as granular activated carbon, as part of a larger treatment strategy.
Utilities may also modify:
- Source-water selection
- Treatment operation
- Carbon replacement or regeneration schedules
- Monitoring programs
If you receive public water and want to know whether atrazine has been detected, check your utility's Consumer Confidence Report or contact the utility directly.
What Should Private-Well Owners Do?
If you live in or near an agricultural area where atrazine is used, a private well may warrant additional attention.
1. Understand Local Land Use
Find out which herbicides are commonly used in the surrounding area.
2. Inspect the Well
Maintain the well cap, casing, grading, and surrounding area to reduce opportunities for surface contamination.
3. Ask About Local Testing Recommendations
State agencies or extension services may know which pesticides are most relevant to local groundwater.
4. Use Laboratory Testing
If atrazine is a specific concern, request appropriate pesticide analysis rather than relying on general-purpose test strips.
5. Choose Treatment Based on the Results
If atrazine is detected, look for a treatment system with contaminant-specific test data or certification and follow replacement requirements carefully.
6. Retest as Appropriate
The appropriate testing frequency depends on local risk, source conditions, previous results, and guidance from your laboratory or health authority.
Can You Boil Atrazine Out of Water?
Boiling should not be relied upon to remove atrazine from drinking water.
Boiling is primarily useful for addressing many microbial concerns during an appropriate boil-water advisory.
It is not a general chemical-contaminant removal process.
For chemical contamination, use a treatment technology specifically designed and tested for that chemical rather than assuming boiling will solve the problem.
Does Atrazine Have a Taste, Smell, or Color?
Atrazine contamination at drinking-water concentrations should not be diagnosed by taste, smell, or appearance.
Water that looks completely clear may still contain atrazine.
Conversely, strange-tasting or discolored water may be caused by entirely different substances.
This is why laboratory testing and utility monitoring are more useful than sensory clues.
How Does Atrazine Compare With Other Pesticides?
"Pesticide" is a broad category containing many different chemicals.
Different compounds vary in:
- Toxicity
- Persistence
- Solubility
- Mobility in soil
- Likelihood of reaching groundwater
- Response to treatment
A treatment system that reduces atrazine should not automatically be assumed to reduce every other herbicide or pesticide to the same extent.
See our Pesticides and Drinking Water Guide for a broader explanation.
Where Does Berkey® Filtration Fit?
If you are evaluating any drinking-water filter for atrazine, focus on the performance information for the specific filter element rather than relying on the brand name or filtration category alone.
Different Berkey®-compatible filter elements have different media formulations, test results, rated capacities, and certifications.
For current contaminant-specific information, review our Water Filter Test Results and Berkey® Replacement Filters Guide.
Do not assume that every carbon-based or gravity-fed filter has been tested for atrazine. Check the documentation for the exact filter element being considered.
Frequently Asked Questions
What is atrazine?
Atrazine is a synthetic triazine herbicide used primarily to control broadleaf and grassy weeds in agricultural crops such as corn, sorghum, and sugarcane.
How does atrazine get into drinking water?
Atrazine can move from treated agricultural land into streams, rivers, reservoirs, or groundwater through runoff, drainage, or movement through soil.
What is the EPA limit for atrazine in drinking water?
The federal Maximum Contaminant Level for atrazine in regulated public drinking water is 0.003 mg/L, equivalent to 3 parts per billion.
Is 3 ppb the same as 3 mg/L?
No. Three parts per billion is 0.003 milligrams per liter. Confusing the units would result in a thousand-fold difference.
Can you taste atrazine in drinking water?
Do not rely on taste or smell to detect atrazine. Laboratory testing or public-water monitoring is required to determine whether it is present.
Does atrazine cause cancer?
EPA has classified atrazine as not likely to be carcinogenic to humans. Some epidemiological studies continue to investigate possible associations with cancer, but atrazine should not be described as a proven human carcinogen.
Does atrazine affect hormones?
Animal studies have found effects on reproductive and neuroendocrine signaling at sufficiently high exposures. Translating those findings into specific human health effects at environmental drinking-water levels requires caution.
Can atrazine affect pregnancy?
Animal research and some human observational studies have raised questions about reproductive and developmental outcomes. The evidence does not establish that ordinary environmental exposure directly causes a particular birth defect or pregnancy outcome.
Is atrazine common in private wells?
The likelihood varies by region, land use, soil, geology, well construction, and pesticide use. Wells near agricultural areas where atrazine is used may warrant targeted testing.
Does activated carbon remove atrazine?
Granular activated carbon can reduce atrazine when appropriately designed and maintained. Look for atrazine-specific performance data or certification for the finished treatment system.
What NSF standard covers atrazine reduction?
Atrazine reduction can be included as a certified health-effects claim under NSF/ANSI 53 for qualifying drinking-water treatment products.
Does reverse osmosis remove atrazine?
Some reverse-osmosis systems can reduce atrazine levels, particularly when used as part of a multistage system. Verify performance for the exact model.
Does boiling remove atrazine?
Boiling should not be relied upon as an atrazine-removal method. Use treatment specifically evaluated for chemical-contaminant reduction.
How should I test well water for atrazine?
Contact an accredited drinking-water laboratory and ask for atrazine analysis or an appropriate pesticide panel. Local health or environmental agencies may help identify which pesticides are relevant in your area.
How often should I test my well for atrazine?
There is no universal three-year schedule appropriate to every well. Testing frequency should reflect local agricultural use, previous test results, well vulnerability, seasonal conditions, and guidance from state or local authorities.
Final Thoughts
Atrazine is an important drinking-water contaminant to understand because it is widely used in agriculture and can move from treated land into surface water and groundwater.
EPA regulates atrazine in public drinking water at 3 ppb.
Scientific research has identified reproductive and neuroendocrine effects in animals and continues to examine possible effects in humans, but many health claims found in older articles overstate what the current evidence can establish.
If atrazine is a concern where you live:
- Review your public-water report or test your private well.
- Do not rely on taste, smell, or appearance.
- Choose treatment based on atrazine-specific performance.
- Maintain the treatment system in accordance with its rated service life.
The most useful sequence is simple: determine whether atrazine is actually present, compare the result with applicable drinking-water standards, and then choose a treatment system with documented atrazine-reduction performance if treatment is needed.