By Peter S. Cartwright, PE

Every time water goes down the drain, whether to a sewer, septic system, storm drain or wherever, it carries contaminants with it, which usually end up in someone’s drinking water. Included are unmetabolized pharmaceuticals, chemicals and particles from hand and face washing, bathing, laundry, the toilet—from virtually any and all human activity. The contaminants are in tiny concentrations, but from many thousands of sources and, as our use of pharmaceutical and personal care products (PPCPs) increases, our drinking water is becoming more contaminated. No scientific connection between this contaminated drinking water and human health has yet been made, but in this writer’s opinion, it will surely come. There’s plenty of anecdotal evidence to support this belief. This article addresses the sources of water contaminants, their possible health effects and offers some guidance on what we, as responsible caretakers of this planet and concerned consumers, can do now and in the future.

Virtually every water source, whether wells, rivers, lakes, oceans or rainwater, requires some treatment to make the water potable. The 1974 US EPA Safe Drinking Water Act is one of our fundamental environmental laws to ensure this. At this time, the act addresses about 100 contaminants and lists the maximum acceptable concentrations for each, above which water is not considered safe to consume for drinking or cooking. These particular contaminants have undergone thorough scientific screening and risk-assessment protocols, but they represent only a tiny fraction of the trace chemicals that are actually in our water supplies. Additional chemicals are being assessed and some will ultimately be added, but it is a (necessarily) slow process.

What is the issue?
Globally, we now produce more than 85,000 different chemicals,1 many of which end up in our drinking water. Chemicals are used to manufacture 96 percent of consumer products; the average adult uses nine products per day containing 126 different chemicals.2 Fertilizers, pesticides, herbicides and antibiotics are all also used in agriculture and animal husbandry operations. Whether from hand washing, bathing, showering, laundry, dish washing, toilet use—no matter for what purpose we use water, it carries contaminants down the drain. If this water enters a municipal wastewater treatment system, it ultimately ends up in a body of water (lake, river, etc.), which often becomes a source of drinking water. If the wastewater is directed into a septic system, the treated water percolates into the earth, where it usually enters an aquifer or other water supply. Weather events generating runoff from lawn and agricultural surfaces also contribute to this contamination. It’s a fact of life: virtually every time water goes down the drain, it is carrying some contaminants that end up in someone’s drinking water.

Many of the pharmaceutical products we ingest are not completely metabolized, pass through the body and contribute to this contamination, as illustrated in Figure 1. America is the largest pill-popping nation in the world, with 70 percent of us taking one prescription a day, 50 percent taking two and 25 percent five or more per day.3 Additionally, because people are living longer, more pharmaceuticals are consumed and more end up in the water. Opioid addiction has become a crisis. In the US alone, in 2016, almost 4.5 billion medical prescriptions were issued.4 Other sources of contaminants include food, toothpaste, artificial sweeteners, caffeine, vitamins, as well as cosmetics, lotion, sunscreen, perfume, deodorant—the list goes on and on.

The primary contaminants in toilet discharges are organic materials with high concentrations of what is known as biochemical oxygen demand (BOD). BOD is readily broken down into generally benign components during the traditional sewage treatment process. On the other hand, this water (and virtually all other waters leaving any facility of human or animal activity) will contain tiny concentrations of other contaminants, as described above. These are mainly in two forms: dissolved organic compounds and tiny particles, fibers or other insoluble materials.
Contaminants in the first form are known by many acronyms:

  • PPCPs (pharmaceutical and personal care products)
  • CECs (contaminants of emerging concern)
  • EPOCs (emerging pollutants of concern)
  • EPPPs (environmental persistent pharmaceutical pollutants)
  • APIs (active pharmaceutical ingredients)
  • EDCs (endocrine-disrupting chemicals [compounds])

The acronym EDC describes specific chemicals that interfere with human hormone function; ongoing investigations conclude that even very low concentrations may disrupt the hormones related to obesity, diabetes, human reproduction processes and various cancers (more on EDCs later). The illicit drug of choice in a particular city can be identified by analyzing the water leaving its sewage treatment plant. [In my home state of Minnesota, a 2013 study of 50 lakes found PPCPs in 47 of them. They included DEET (used in mosquito and tick repellents), cocaine, caffeine and triclosan (an antibacterial agent in hand soap). None of the lakes were located near a municipal wastewater plant.5] The above examples are just from residential activity and don’t account for the huge number of other contaminants from our agricultural and industrial activities.

The second form, particles, can range from tiny fibers to bits of plastic. Known by such terms as nanofibers, nanoparticles, microplastics, nanomaterials and others, they add to the myriad of manufactured contaminants which do not readily degrade in nature. Examples include exfoliant cosmetic beads, lint, particles washed out of the air, laundry and carpet cleaning wastewater and many more. The contribution by plastic alone is illustrated in Figure 2. Because of their benefits as catalysts and as additives, industry is starting to use many more nanoparticles in manufacturing processes in such areas as medicine, energy and electronics. It is estimated that there are more than 1,000 nano-enabled products produced in the industrialized countries today, and this number is increasing rapidly.

A 2016 study at Loyola University of Chicago indicates that up to 4.5 million pieces of plastics per day are released into rivers by municipal wastewater treatment plants. Interestingly, this is the quantity released after the plants have removed 90 percent of the incoming microplastics.6 In 2016, the US Geological Survey (USGS) participated in an extensive study, Microplastics in the Great Lakes. One outcome was the document, Microplastics in our Nation’s Waterways.7 The categories of microplastics identified in this document included beads, films, foams, fragments and fibers, with the latter comprising over 70 percent of all the microplastics.

Our oceans contain huge masses of plastic debris known as gyres or garbage patches. There are five major gyres, with the largest, the Great Pacific, estimated to be at least the size of Texas in area.8 Most of these plastics are susceptible to degradation by ultraviolet radiation from the sun and break down into relatively inert microplastic particles. They are often coated with dissolved organic PPCPs, which can then be released into water supplies.7 Surprisingly, they are found even in such remote locations as the Antarctic.

So, how many of these chemicals and nanoparticles are in our drinking water? Obviously, the concentrations vary from place to place and from time to time; however, the concentrations are very, very small, measured in parts per trillion. What is a part per trillion? It’s about one second in 32,000 years, a pinch of salt in 10,000 tons of potato chips, or a six-inch leap in a journey to the sun.

Is there a health risk?
Does this tiny concentration of the huge number of these various contaminants pose a health problem? So far, there is no scientifically proven link, but lots of anecdotal evidence.

A Canadian study in 2008 provides some of this evidence:9 In 20 industrialized nations, the birthrate for boys has declined every year for the past 30 years. There has been a 200-percent increase in male sex organ abnormalities over the last 20 years. The average sperm count of North American college students has dropped by over 50 percent in the last 50 years. Up to 85 percent of the sperm in healthy males contains damaged DNA. Over the last 50 years, there has been a 300-percent increase in testicular cancer. For many years, there have been reports of feminization in fish and amphibians, as well as documented genitalia deformities in such diverse animal populations as bears, panthers, sea lions, whales, birds, alligators and others. Between 1999 and 2003, in a population of Chippewa aboriginal peoples in southwestern Ontario, Canada, the birth ratio of boys to girls declined from roughly 50/50 to 33/67.10

Significant research is underway on EDCs. A citation in the journal Endocrine Reviews, contains the statement: “Whether low doses of EDCs influence certain human disorders is no longer conjecture, because epidemiological studies show that environmental exposures to EDCs are associated with human diseases and disabilities.”11 A follow-up review in 2015 contains the statement: “It simply is not reasonable to assume a chemical is safe until proven otherwise. Clearly, not all chemicals are EDCs, but substantial information needs to be provided before inclusion of a new compound in a food-storage product, a water bottle, health and beauty products or a household product. The BPA substitute, BPS, is now shown to have endocrine-disrupting activity on par with BPA in experimental studies discussed in EDC-2. A further need for precaution is based on evidence that individuals exposed to EDCs may carry that body burden for their entire lives in the case of long-lived chemicals; that even short-lived chemicals may induce changes that are permanent and that some actions of EDCs are observed in an individual’s offspring. Transgenerational effects of EDCs mean that even if a chemical is removed from use, its imprints on the exposed individual’s DNA may persist for generations and possibly forever.”12

Chlorine, the common water disinfectant used in municipal drinking water treatment plants can chemically react with some PPCPs and produce DBPs, a class of which trihalomethanes (THMs) contains chemicals known to cause cancer. In recognition of this, US EPA has established a maximum limit for THM compounds, listed in the Safe Drinking Water Act. Many municipalities are adding ammonia to chlorine to produce chloramines, which do not generate dangerous DBPs. The formation of these compounds is an example of the complex chemistry associated with PPCP contamination.

In addition, fluorine-based chemical contamination of aquifers has become a major issue in many areas. Under the general acronym, PFAS (poly- and perfluoroalkyl substances), they are major components of firefighting foam, Teflon® and Scotchgard® products, coatings on carpeting, clothing, fast-food wrappers and many other consumer products. PFAS exposure has been linked to cancer, obesity, immune system suppression and endocrine system disruption.13

US EPA has suggested advisory levels but has not established specific limits for any of the many fluorine-containing chemicals in the environment. The National Groundwater Association has recently published a document, Groundwater and PFAS: State of Knowledge and Practice. “It is intended to provide technically defensible guidance useful in defining an appropriate path forward for a client, a water resource, or a regulatory action.”14

The US Department of Health and Human Services Centers for Disease Control and Prevention (CDC) publishes a report every two years, The National Report on Human Exposure to Environmental Chemicals, which is “…a series of ongoing assessments of the US population’s exposure to environmental chemicals by measuring chemicals in people’s blood and urine, also called biomonitoring.”15 This report provides exposure information with regard to chemicals in the environment that enter the human body. The Fourth Report (2017) includes data for 308 chemicals.
Today, there is a continuous stream of news releases on credible scientific studies that address links between common household chemicals and various health effects. Here are some examples:

  • In a 2014 study at Columbia University, two chemicals found in such products as lipstick, hairspray, nail polish, dryer sheets and vinyl fabrics (phthalates: suspected EDCs) lowered the IQ of children born to mothers exposed to them.16
  • A recent Virginia Tech study has found a connection between quaternary ammonium compounds (quats) found in cleaners, laundry detergent, fabric softener, shampoo, conditioner and eye drops, and birth defects in laboratory rodents.17
  • Again, common household products are implicated in a Washington University in St. Louis study that linked them with ovarian function, resulting in women experiencing menopause two to four years earlier than normal.18

It is very important to underscore the fact that, so far, there is no proven link between these trace contaminants and human health. Although many scientific studies are underway, there is lack of conclusive proof that PPCPs are harmful. On the other hand, with so many different chemicals in our drinking water (in this writer’s opinion), it is only a matter of time before a health risk is identified.

Here are some unanswered questions:

  • What is the specific risk: cancer, autism, ADHD, Parkinson’s disease, diabetes, allergies, something else?
  • What is the most vulnerable population: babies, the elderly, pregnant women, adults with compromised immune systems?
  • Which chemicals are more dangerous than others: those that bioaccumulate in the body; those that break down in the body?
  • Are there combinations of them that present even greater risk?
  • Do they react with each other to produce other dangerous compounds?
    The evidence is certainly persuasive, but not yet conclusive. In Part 2, we will offer suggestions as to how to address this contamination issue with changes to our personal practices, legislation and the utilization of treatment technologies at a single tap. I also offer my predictions for the future.


  1. ANH-USA. June 4, 2013
  6. Hoellein, Timothy. 24 February 2016. “Wastewater Treatment Plants Significant Source of Microplastics in Rivers, New Research Finds.” American Geophysical Union.
  8. 7 June 2017.
  10. Environ Health Perspect. 2005 Oct;113(10):1295-8.
  11. Vandenberg LN., Colborn T, Hayes TB, Heindel JJ, Jacobs DR, Lee DH, Shioda T, Soto AN, vom Saal FS, Welshons WV, Zoeller RT, Myers JP. June 2012. “Hormones and Endocrine-Disrupting Chemicals: Low-Dose Effects and Nonmonotonic Dose Responses.” Endocrine Reviews. 33(3):378-455.
  12. Gore AC, Chappell VA, Fenton SE, Flaws JA, Nadal A, Prins GS, Toppari J, Zoeller RT. December 2015. “Executive Summary to EDC-2: The Endocrine Society’s Second Scientific Statement on Endocrine-Disrupting Chemicals.” Endocrine Reviews. 36(6):593-602.
  13. Hu XC, Andrews DQ, Lindstrom AB, Bruton TA, Schaider LA, Grandjean P, Lohmann R, Carignan CC, Blum A, Balan SA, Higgins CP, Sunderland EM. “Detection of Poly- and Perfluoroalkyl Substances (PFASs) in U.S. Drinking Water Linked to Industrial Sites, Military Fire Training Areas, and Wastewater Treatment Plants.” Environmental Science & Technology Letters. August 9, 2016.
  16. Columbia University’s Mailman School of Public Health. “Prenatal exposure to common household chemicals linked with substantial drop in child IQ.” ScienceDaily, 10 December 2014.
  17. Virginia Tech. “Common household chemicals lead to birth defects in mice, research finds.” ScienceDaily, 17 June 2017.
  18. Washington University in St. Louis. “Earlier menopause linked to everyday chemical exposures.” ScienceDaily, 28 January 2015

About the author
Peter Cartwright entered the water and wastewater treatment field in 1974 and has had his own consulting engineering company since 1980. He is a graduate of the University of Minnesota, with a degree in Chemical Engineering and is a registered Professional Engineer in that state. Cartwright has authored over 300 articles, written several book chapters, presented more than 300 lectures around the world and holds several patents. He is a recipient of both the Award of Merit and Lifetime Member Award from the Water Quality Association and is the Technical Consultant to the Canadian Water Quality Association. Cartwright was the 2016 McEllhiney Distinguished Lecturer for the National Ground Water Research and Educational Foundation. He can be reached at [email protected]; his website is


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