Stephanie Angione, Ph.D.  |  Scientific Contributor

Pesticides are chemicals used to kill environmental pests including insects, weeds, fungi and rodents. These are commonly divided into insecticides (used to specifically target and kill insects) and herbicides (used to kill undesirable plants or “weeds”). The most widely used agricultural pesticides are herbicides, which account for 40% of all pesticide use in the US. In typical agriculture, pesticides are applied to crops in order to provide protection against destructive insects and invasive weeds or fungi. By design, pesticides kill or deter pests and thus are toxic to their intended target organisms. Additionally, many pesticides are toxic to humans, and organochlorine pesticides are 9 of the 12 most toxic organic chemicals, as outlined by the Stockholm Convention in 2001.

Which Pesticides Are Most Commonly Found In US Water Systems?

The most comprehensive information available about pesticide occurrence at the national level is part of a 10-year program by the National Water-Quality Assessment (NAWQA), part of the US Geological Survey (USGS). It provides information about pesticide concentrations in streams and groundwater from data collected between 1991-2001.

Major findings of this study are that pesticides exist in both streams and groundwater throughout the US, in both urban and rural areas, but seldom occur at concentrations that will affect human health. Of the water systems studied, pesticides were found 90% of the time in streams throughout the US in urban and agricultural areas. Groundwater sources were less affected by pesticide contamination, with shallow groundwater sources in agricultural and urban areas having pesticides 61% and 55% of the time respectively.

The most commonly detected pesticides in stream water include five agricultural herbicides, atrazine, metolachlor, cyanazine and acetochlor and five non-agricultural herbicides in urban areas, including simazine, prometon, tebuthiuron, 2,4-D and diuron and three insecticides – diazinon, chlorpyrifos and carbaryl (Figure 1).

Figure 1: Percentage of samples found with pesticide contamination in agricultural and urban stream water (upper) and groundwater (lower).

Additionally, pesticides detected the most frequently in fish and streambed sediment were organochloride pesticides and degradation products (Figure 2). Organochlorides were used heavily in the 1950s and 1960s and were largely abandoned by the 1980s. However these compounds including DDT are very persistent in soils, sediments and animals, and were thus found at high levels in stream sources.

Figure 2: Percentage of samples of fish tissue containing organochlorine pesticides and degradation products in agricultural and urban streambeds

Despite the widespread existence of pesticides in water systems, levels of pesticides only exceeded human health benchmarks in about 10% of agricultural streams, and 7% of urban streams studied. It should be noted that for public water supply intakes that withdraw water from streams in the US, only 12% are from an agricultural land-use areas, and only 1% from an urban land-use areas. As for groundwater, only 1% of wells sampled had pesticide levels above human health benchmarks.

As for the pesticides present at these excessive concentrations, the most commonly found were atrazine, cyanazine, diazinon and dieldrin. Notably, stream contamination was commonly atrazine and cyanazine and well contamination was dieldrin, which is no longer used but is a known persistent pollutant.

While the compounds discussed above were detected the most frequently in the study period from 1992-2001, pesticide usage changes as new pesticides are developed. A new study of streams sampled in the US in 2015 by the USGS indicates the existence of the relatively new class of pesticides- neonicotinoids, in US water systems. The study found at least one neonicotinoid detected in 53% of all samples, with imidacloprid detected the most frequently (37%). Guidelines on the effects of neonicotinoids in humans and safe levels of exposure have not yet been systematically investigated.

In addition, a 2022 study revealed that very high levels of PFAS were detected in 6 of 10 varieties of pesticides commonly used in rural and agricultural environments. 

For more information on tracking of common pollutants and pesticides in drinking water, the USGS has an interactive map to examine levels of pesticides nationwide.

How Is Pesticide Contamination Regulated?

The EPA regulates pesticides nationally under the Federal Insecticide, Fungicide and Rodenticide Act to protect human health and the environment. Aside from the 141 banned and severely restricted pesticides, the EPA has set limits on the allowable amount of pesticides in food and drinking water. Many pesticides including alachlor, atrazine, carbofuran, chlordane, 2,4-D, glyphosate, heptachlor, and simazine are included in the national primary drinking water standards that outline the maximum contaminant level for each compound. Public water suppliers are required to maintain levels below the maximum contaminant level for all compounds listed. The EPA has also established 394 human health benchmarks for pesticides that are registered for use on food crops but are not regulated under the national primary drinking water standards.

How Do I Find Out If My Drinking Water Is Contaminated With Pesticides?

If you are concerned about the effects of pesticides in your drinking water and are served by a public water system, your local water supplier is required to issue a Consumer Confidence Report that lists contaminant levels in the water supply. If you have a private well, a laboratory can test your drinking water.

Although the EPA regulates many pesticides as drinking water contaminants, there are many that are not. Additionally, levels of pesticide contamination can vary widely depending on the agricultural season and pesticides can be used in water systems to control pests like mosquitos.

If you get water from a household well, the local health department should have information about ground water quality and contaminants of concern, but it is often a good idea to have your water tested by a certified laboratory for contaminants. The EPA’s Safe Drinking Water Hotline (800-426-4791) can provide additional resources in your local area. It is also important to consider the proper use of pesticides at home if you have a private well, as pesticide runoff can contribute to well contamination.

How Do I Remove Pesticides From Drinking Water?

A home water filtration system can remove pesticides from drinking water that may not fall under EPA regulation. Water filter systems that use activated carbon as part of the filtration media blend or reverse osmosis can be effective in removing pesticides from water. Contrary to what some people tell you, boiling/freezing water does NOT remove pesticides from drinking water!

Do You Have More Questions About Pesticides In Drinking Water?

At Hydroviv, we make it our business to help you better understand your water. As always, feel free to take advantage of our “help no matter what” approach to technical support! Our Water Nerds will work to answer your questions, even if you have no intention of purchasing one of our water filters. Reach out by dropping us an email (hello@hydroviv.com) or through our live chat. You can also find us on Instagram, Twitter or Facebook!

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Emma Schultz, M.S.  |  Scientific Contributor
Updated 12/1/2023 to include latest numbers of Superfund sites by state. 

Do you know where your nearest EPA Superfund Site is? Chances are there is one close by, given that one out of every five Americans lives within three miles of an EPA-designated major hazardous waste site. There are two sites located within four miles of my childhood home, in an idyllic and quiet suburb of St. Paul, Minnesota. I now live within the same distance of five sites -- and I had no clue. 

Superfund Sites - Environmental Hazards

What Is The Superfund Process?

The concept of EPA Superfund Sites is widely known and understood, but the intricacies of the program and the approach to hazardous waste mitigation are elaborate and prolonged, as can be expected of any federally-funded long-term project.

History: 

Resources for homeowners:

Stephanie Angione, Ph.D.  |  Scientific Contributor

What Are Polychlorinated Biphenyls (PCBs)?

Polychlorinated Biphenyls (PCBs) are a class of industrial chemical that were widely manufactured in the US from the 1930s through the 1970s for use in electric equipment such as capacitors and transformers, and also as heat transfer fluids, plasticizers, adhesives, fire retardants, inks, lubricants, cutting oils, pesticide extenders, and in carbonless copy paper.
 
While PCB production slowed in the 1960s and was banned completely in the US in 1979, they are still found in industrial applications due to their chemical longevity. The US congressional ban was enacted due to the fact that PCBs are persistent organic pollutants, which create long lasting environmental toxicity and cause harmful health effects. Products that contain PCBs include old fluorescent lighting fixtures, PCB capacitors in old electrical appliances (pre-1978) and certain hydraulic fluids.
 
Nearly 2 million tons of PCBs have been produced since 1929, 10% of which persists in the environment today. Generally, environmental concentrations of PCBs are low, but due to their chemical inertness they are largely resistant to chemical breakdown or thermal destruction, and thus accumulate in the environment. Additionally, PCBs are highly fat soluble, resulting in the build up of PCBs in animal fat, resulting in higher concentrations of PCBs in top food chain consumers (e.g. predatory fish, large mammals, humans).
 

Where Are PCBs Found In The Environment?

Polychlorinated Biphenyls accumulate primarily in water sources, organic portions of surface soil, and in living organisms.
 

Water

Surface water that is contaminated with PCB waste generally has high levels of PCBs in sediment, as the PCBs attach to organic matter. PCBs can be slowly released from the sediment into the water and evaporate into the air, especially at higher temperatures.

Air

PCBs have been detected throughout the atmosphere, and can be transported globally through air. Concentrations of PCBs in the air are generally the lowest in rural areas and highest in large cites. Areas that are close to bodies of water that were highly contaminated with PCBs from industrial waste (e.g. Lake Michigan, Hudson River) can have higher air concentrations, due to evaporation of PCBs into the air over time.  

Living Organisms

PCBs accumulate in living organisms via bioaccumulation, or uptake from the environment, as well as biomagnification, from consumption along the food chain. Bioaccumulation is typically highest in aquatic species, with bottom feeding species having the highest levels of PCBs due to accumulation in sediment.  PCBs biomagnify up the food chain, as bottom feeders like shellfish are eaten by other species, and thus the greatest levels are found in large predatory fish. This process can also occur on land, as PCB contamination in soil is transferred up the food chain to insects, birds and mammals. Thus, one of the largest sources of PCB exposure and accumulation in humans is from food, specifically meat and fish.

How Do PCBs Impact Humans?

While PCBs have been classified as probable human carcinogens, there is no evidence that the low levels of PCBs in the environment cause cancer. Exposure to high levels of PCBs have primarily occurred through workplace exposure in people who work in plants that manufacture the chemicals. Studies of workers exposed to high PCB levels have shown association with certain types of cancer. These high levels of exposure have also been known to cause liver damage, skin lesions called chloracne, and respiratory problems.

Exposure to PCBs during pregnancy can result in developmental and behavioral deficits in newborns. Additionally, there is evidence that reproductive function can be disrupted due to PCB exposure. Women of childbearing age, or those who are pregnant or nursing should be aware of fish and shellfish advisories to limit consumption of PCB contaminated fish.
There are additional studies that suggest PCB exposure can cause health effects including thyroid dysfunction, liver dysfunction, as well as adverse cardiovascular, gastrointestinal, immune, musculoskeletal, and neurological effects.

How Are PCBs Regulated & Monitored In The US?

With so many sources of PCB exposure from food and water sources, the US government has guidelines on the amount of allowable environmental PCB contamination for each.  

Food

The FDA enforces a tolerance level in fish of 2 ppm, and overall 0.2 -3.0 ppm for all foods. PCBs in paper food packaging are limited to 10 ppm.
 
If fishing recreationally and you plan to eat your catch, check if any local fish consumption guidelines exist for your area. The EPA maintains a national database of fish and shellfish advisories issued by each state. These consumption advisories may recommend limiting the amount of a certain fish consumed, or from specific waters or water sources. As of 2011, five areas have advisories for PCBs in freshwater sources (Missouri, Minnesota, Maryland, Indiana, and District of Columbia) and nine states (Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, and Rhode Island) have PCB advisories for coastal waters.

Drinking Water

Under the Clean Water Act, industrial discharge of Polychlorinated Biphenyls in water is prohibited. The goal is to reach zero contamination in drinking water, but the enforceable maximum level is 0.0005 part per million (ppm).  Additionally, industries are required to report spills or accidental releases to the EPA. 

Routine monitoring of PCB levels in drinking water require the water supplier to maintain the limit enforced by the EPA and must make the data regarding water quality and contaminants public. Every year, the EPA requires water suppliers nationwide to provide a Consumer Confidence Report (CCR), which will include information about water treatment and any known contaminants. These reports are available on the EPA website and should be available on your water company’s website. Additionally, the supplier is required to alert customers of increased levels of PCB contamination as soon as possible.
 
If you get water from a household well, the local health department should have information about ground water quality and contaminants of concern, but it is often a good idea to have your water tested by a certified laboratory if you are worried about PCB (or other) contaminants. The EPA’s Safe Drinking Water Hotline (800-426-4791) can provide additional resources in your local area.

How Can I Remove PCBs From My Water?

If your water has high levels of PCBs in it,  the water should also not be used to drink, prepare or cook food,  or given to pets for consumption without first treating it.  Fortunately, PCBs are effectively removed from water by filters that use activated carbon as part of their active filtration media blend.
 
Hydroviv makes it our business to help you better understand your water.  As always, feel free to take advantage of our “help no matter what” approach to technical support!  Our water nerds will work to answer your questions, even if you have no intention of purchasing one of our water filters.  Reach out by dropping us an email (hello@hydroviv.com) or through our live chat. You can also find us on Twitter or Facebook!

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Eric Roy, Ph.D.  |  Scientific Founder

This past week, the Environmental Working Group (EWG) released a website where people punch in their zip code, and view contaminants found in their water. As a company that uses water quality data to optimize each customer’s water filter, we applaud EWG for putting in the enormous amount of time & effort to build the database so the public can learn about their water. Unfortunately, we are seeing that these data are being used to generate inflammatory headlines, which can leave consumers confused and unnecessarily panicked.

We will be updating this water quality database blog post as more questions come in. If you have your own question, please reach out to us (hello@hydroviv.com). One of our water nerds will do their best to get back to you very quickly, even if it’s outside of our business hours.

Frequently Asked Questions 

Updated July 31, 2017

Are All Potential Contaminants Listed In The EWG Tap Water Database?

No. The EWG Tap Water Database pulls data from municipal measurements, but municipalities are only required to test for certain things. Simply put, you can’t detect what you don’t look for. One example of this can be seen by punching in Zip Code 28402 (Wilmington, North Carolina) into the EWG Tap Water Database. GenX, a chemical that has been discharged into the Cape Fear River by Chemours since PFOA since 2010, is not listed, even though it’s been in the center of a huge topic of conversation for the past 2 months in the local media.

Why Is The “Health Guideline” Different Than The “Legal Limit?”

The two different thresholds use different criteria. For example, the “Health Guideline” cited by EWG for carcinogens is defined by the California Office of Environmental Health Hazard Assessment (OEHHA) as a one-in-a-million lifetime risk of cancer, while the “Legal Limit” refers to the MCL which is the limit that triggers a violation by EPA. The OEHHA's criteria are established by toxicological techniques, while the EPA limits are negotiated through political channels. We wrote an article that addresses this topic in much more detail for those who are interested.

Why Am I Just Learning About This Now?

The EPA's Safe Drinking Water Act requires municipalities to make water quality test data public in Consumer Confidence Reports. These reports are required to talk about the water's source, information about any regulated contaminants found in the water, health effects of any regulated contaminant found above the regulated limit, and a few other things. As discussed before, the data in the EWG report use different criteria than the EPA, and it's hard for people to make sense of what's what.

Are The Data Correct If My Water Comes From A Private Well?

No. The EWG Tap Water Database only has data for municipal tap water. Private wells are completely unregulated, and there's no requirement to conduct testing. If you'd like us to dig into our additional water quality databases to help you understand likely contaminants in your private well, we're happy to do so. We don't offer testing services, but we're happy to help you find an accredited lab in your area, give advice on which tests to run, and help you interpret the results! We offer this service for free.

What About My City's Water Quality?

Hydroviv makes it our business to help you better understand your water. As always, feel free to take advantage of our “help no matter what” approach to technical support! Our water nerds will work to answer your questions, even if you have no intention of purchasing one of our water filters. Reach out by dropping us an email (hello@hydroviv.com) or through our live chat. You can also find us on Twitter or Facebook!

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Eric Roy, Ph.D.  |  Scientific Founder

***Updated to include 2021 water quality data***

For Hydroviv’s assessment of Washington, D.C. drinking water, we aggregated water quality test data from D.C. Water (the public utility provider) and the U.S. Environmental Protection Agency (EPA), as well as from samples that we collect and analyze. We cross reference these data with toxicity studies in the scientific and medical literature, and look at upcoming regulatory changes. The custom water filters that build and sell for Washington, D.C. are optimized with these factors in mind.

Lead In DC Tap Water

Washington, D.C. is an old city with a lot of lead service lines, so it's not a huge surprise that D.C. has had such a big problem with lead in drinking water. Lead leaches from lead-containing pipes, solder, and fittings, unlike most contaminants which are found at the source. D.C. Water uses two sampling periods when testing for lead: January-June and July-December. In the 107 samples pulled during January-June period, the 90th percentile concentration for lead was 2 parts per billion, and 3 samples were above the 15 part per billion Action Level (AL). In the 105 samples pulled from the July-December sampling period, the 90th percentile concentration was 3 parts per billion, and one of the collected samples exceeded the action level. Although these results indicate that D.C. is in citywide compliance with federal water quality standards, it's important to point out that EPA, CDC and the American Academy of Pediatrics all agree that there is no safe level of lead for children. The bottom line is that the federal standards allow up to 10% of sampled taps to have lead concentrations over 15 parts per billion.

We highly recommend that Washington D.C. residents take a look at this map to see if their home has a lead service line, because those homes (and homes with plumbing that predates 1986) are most susceptible. We also highly recommend taking advantage of D.C. Water's free lead testing program, and any families with small children take steps to remove any lead from their water, even if they don't use a Hydroviv filter. It's important to remember that most pitchers and fridge filters do NOT remove lead from water. Hydroviv Undersink filters are NSF/ANSI 53 certified to remove lead from drinking water.

Detectable Levels of Unregulated Contaminants In DC Tap Water

One thing that has caused quite a bit of alarm from several people in this year's report is that several herbicides, VOC's and synthetic compounds were all found at detectable levels in D.C. drinking water. Herbicides such as Dalapon, shouldn't be a huge surprise seeing that D.C. draws water from near at the end of a river, so there is opportunity for agricultural runoff to enter the river. For anyone who is interested, The Maryland DEP has made the Source Water Assessment for the Potomac River (404 pages) publicly available. 

DC's Water Source: Potomac River

The Washington Aqueduct (operated by the Army Corps of Engineers) draws water from the Potomac River for treatment. District of Columbia Sewer and Water Authority (aka D.C. Water) purchases treated water from the Washington Aqueduct, and is responsible for distributing it throughout D.C. We also have a stand-alone article that entirely focuses on the Potomac River.

Left Out Of The Report: Chromium 6

We were a bit surprised to see Chromium 6 left out of the 2019 water quality report for Washington, D.C. Even though it's a known human carcinogen, chromium 6 is categorized as an "Emerging Contaminant" by EPA but is not regulated on its own. D.C. Water (and 6000 other municipalities) participate in the Unregulated Contaminant Monitoring Rule (UCMR3), which is a nationwide testing program to study "emerging" contaminants. UCMR acknowledges that contaminants on the list most likely cause adverse health effects, including cancer. The concentration in D.C. water average 86 parts per trillion. For perspective, these levels are roughly 4-5x higher than what The State Of California set as a public health goal. We believe that people should not wait for EPA to begin regulating chromium 6 on its own, and filter their water, even it they aren't using our product. It's important to remember that most pitchers and fridge filters do NOT remove chromium 6 from water.

Per and Polyfluoralkyl Substances (PFAS) In Washington, D.C. Drinking Water

PFAS are a category of chemicals found in various non-stick/stain resistant products, as well as fire fighting foam. PFAS are considered to be "emerging contaminants" because they are not currently regulated by EPA, but are known to be toxic and persistent in the environment. PFAS have been detected at surrounding military installments that are in close proximity to the Potomac River (DC's source water). Most municipalities are not required to test for, or remove, PFAS from drinking water. Not all filters are designed to remove PFAS from drinking water. If you'd like find water filters that remove PFAS from tap water, check out this Duke/NC State study.

Disinfectant

The primary disinfectant used to treat Washington DC's tap water is chloramine, except for a few weeks in the spring when DC switches over to chlorine. D.C. (and a growing number of municipalities) use chloramine instead of chlorine for a few reasons: for one, chloramine is more persistent than chlorine, so it maintains its ability to disinfect the water further away from the source. On the other side, chloramine does not quickly dissipate from water if left in a jug overnight. If you want to get it out of the water, you'll need a filter designed to remove chloramine, because a regular charcoal filter doesn't do a great job removing it.

If you want to learn more about Hydroviv's water filters, check out www.hydroviv.com, or drop us a line through live chat or email (hello@hydroviv.com). Even though we sell our products nationwide, Hydroviv is a DC company and we take care of our own backyard!

As always, feel free to take advantage of our "Help No Matter What" approach to technical support. We will answer your questions about water quality even if you have no desire to purchase one of our products. 

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