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Trace Pharmaceuticals & Personal Care Products

Trace pharmaceuticals, also called microconstituents or emerging contaminants, are products that enter the water supply through animal-based agricultural runoff or human sources. These compounds have a wide variety of functions and sources from agriculture, manufacturing, food additives and artificial sweeteners, to medications and personal care products. Many pharmaceuticals enter the water supply when unwanted or expired medicines are disposed of by flushing down the toilet or dumping down the drain. Rather than doing this, please see the FAQ below to learn how to dispose of unwanted pharmaceuticals properly. In addition, many of these pharmaceuticals, food additives, and especially artificial sweeteners are used in doses that exceed the body’s capability to absorb them, so they end up passing through the user and back into water systems.


Has Denver Water found these compounds?

Denver Water has participated in some of the earliest research projects looking for microconstituents (including projects with Colorado State University and UC Santa Barbara). Additionally, Denver Water performs periodic sampling and analysis for these compounds in our watershed and finished water. To date, estrogenic compounds have not been detected but trace amounts of antibiotics, pharmaceuticals, artificial sweeteners, and personal care products have been detected at part per trillion concentrations (one part per trillion is equivalent to one second in 31,700 years). Among the personal care products detected, the most common were DEET (insect repellent), propylparaben (cosmetics preservative), and salicylic acid (topical acne medication).

Finding those trace amounts shows that even high-quality watersheds are experiencing the impacts of consumer products.

Are these substances a health risk?

Though research on pharmaceuticals in the water supply has been occurring for over a decade, the scientific body of knowledge on potential human health effects is still considered to be in its infancy. Performing a toxicological risk assessment for each pharmacological compound in drinking water is time intensive, with only a small percentage of pharmaceuticals having been assessed. Consequently, the EPA has no current or proposed regulations for these substances. Of the compounds that have been fully assessed, all have been detected at levels tens of thousands of times smaller than a therapeutic dose with detection in finished drinking water being rare. According to preliminary studies conducted by the World Health Organization and the EPA, several water treatment techniques (including those used at Denver Water treatment plants) are effective at removing most pharmaceuticals and personal care products from source water1,2. Denver Water’s current datasets align with these findings. If future research indicates that certain substances should be removed from water and identifies the best way to do so, we will actively investigate how to do that.


  1. World Health Organization. (‎2012)‎. Pharmaceuticals in drinking-water. World Health Organization.
  2. United States Environmental Protection Agency. (August 2010). Treating Contaminants of Emerging Concern. United States Environmental Protection Agency.

How do I dispose of medications?

The Colorado Department of Public Health and Environment oversees the Colorado Medication Take-Back Program for disposing unwanted medication in a secure and environmentally safe way. In addition, some local law enforcement agencies and pharmacies accept unwanted medications. Disposing of medication at safe sites, rather than flushing them down a toilet or throwing them away, will help keep pharmaceuticals out of our drinking water.