Pharmaceuticals & Water Supplies

We all know that prescription drugs are vital for fighting and curing serious disease. However, trace levels of pharmaceutical compounds have been detected in water supplies throughout the world. The good news is that studies conducted to date by the United States Geological Survey and others have not found any significant levels of harmful contaminants in our groundwater basin.

So, what does this mean for Orange County water users and for Anaheim in particular?


Pharmaceutical compounds and prescription medications can enter the environment through the discharge from wastewater treatment plants. While this issue is relatively new to the general public, water supply professionals have been studying the presence of trace levels of pharmaceuticals in drinking water for many years. Technological improvements have allowed laboratories to detect compounds in water at trace levels – as low as 1 part per trillion. For reference, a part per trillion is equivalent to a single drop in 1,000 swimming pools, or roughly 1 millionth of a dose of a prescription drug. Therefore, it is not a surprise that trace levels of these compounds can be found in the environment.

There are currently no regulatory standards or requirements to monitor for these substances. Several studies on the use of reclaimed water for groundwater recharge have found no significant threat to public health when conducted in the manner used here in Southern California.

Groundwater Basin Management

The Orange County Water District (OCWD), which manages the groundwater basin in northern and central Orange County, is aware of this issue and is taking action in coordination with Anaheim Public Utilities and other local water providers to assure that our groundwater remains safe, including:
  • Completing the Santa Ana River Water Quality Health Effects Study which researched the long-term public health implications of using treated wastewater for groundwater recharge. The study, which was authored by a team of independent environmental and medical health professionals, concluded that this practice does not threaten public health. Depending on the findings of current and future research, study of the potential health effects of pharmaceuticals may also be conducted.
  • Conducting tracer studies to ensure there is an adequate time before recharged water reaches a municipal water supply well
    • Most pharmaceutical compounds naturally degrade as water travels through rivers, lakes and the subsurface layers of rocks and sand.
  • Ensuring that the Groundwater Replenishment System, which uses purified wastewater for groundwater recharge, includes advanced water treatment techniques that remove pharmaceutical compounds from water
  • Implementing a water quality monitoring program to track the presence of substances correlated with wastewater, including pharmaceuticals
  • Managing the wetlands behind Prado Dam, which provide additional natural degradation of substances in river water prior to it flowing into Orange County
  • Working with the Santa Ana Watershed Project Authority on several matters pertaining to protection of the watershed and water quality
    • This organization works with wastewater treatment plants to ensure that discharges meet all current standards.
In addition, the Water Research Foundation has implemented a wide-ranging program to better understand the significance of trace levels of pharmaceuticals in drinking water. This research, along with research funded by state and federal regulatory agencies, will help determine if new drinking water standards should be established.

Orange County Sanitation District

Locally, the Orange County Sanitation District is taking a leadership role to educate prescription drug users in Orange County on how to properly dispose of unused drugs. At the state level, CalRecycle is developing an improved program for the collection and proper disposal of drug waste.

How You Can Help

Most environmental organizations recommend that unused pharmaceuticals and other personal care products be returned to the pharmacy (if they accept them). Orange County Waste and Recycling maintains a list of drop boxes where unneeded medication can be dropped off. If a pharmacy does not accept the medication and no drop box is available, experts recommend that you dispose of unused drugs by securely wrapping and placing them in your trash.

If you have any specific questions, please email or call the Water Quality Division at 714-765-4556.