When patients go home after receiving their regimen of powerful cytotoxic agents, oncology nurses routinely encourage them to double flush after using the bathroom to ensure that trace amounts of hazardous medication are eliminated from the environment to prevent other members of the household from being exposed. But what happens with chemotherapy chemicals found in human waste as they enter a patient’s septic system—and eventually the water supply?

In rural areas or places without access to a sewer, septic systems are buried below ground and work as a water filtration and separation system. Through mechanisms that separate waste matter from the water, septic systems slowly release water back into the soil. For patients who have septic tanks on their property, the possibility of cytotoxic contamination making it through the filtration system and back into the soil—and possibly their drinking water—may be a concern for families, especially if they rely on well water. 

What the Literature Says

According to Chemotherapy and Immunotherapy Guidelines and Recommendations for Practice, for 48 hours after receiving chemotherapy, patients should flush bodily waste down a toilet—connected to either sewer or septic tank—while the lid is down. No distinction is made for disposal through a septic tank. 

All medications, including chemotherapy agents, have a terminal half-life (i.e., the time it takes chemicals to essentially lose half their potency), which can be helpful to determine the amount of time a medication will take to deteriorate. This information is typically included with the drug and can be reviewed with pharmacy colleagues and shared with patients. 

With a septic system’s filtration and separation process, most agents will have time to decompose and lose their potency before being released into the soil. Once wastewater is released from the septic system into the soil, the dirt functions as a natural decontamination process. As water slowly moves up from underground to ground level, the soil removes harmful contaminants, bacteria, and viruses. 

What This Means for Oncology Nurses

Ultimately, oncology nurses aren’t required or expected to be well-versed on the mechanisms of septic systems or sewer lines. However, as frontline resources for patients, nurses can share education and guidelines to better protect them against inadvertent contamination. 

If patients or family members are concerned about safety issues related to chemotherapy waste in a septic system, oncology nurses can remind them to flush appropriately, leave the toilet lid closed for 48 hours after receiving chemotherapy, wash their hands and potentially contaminated areas, and make sure any pregnant women, children, and pets avoid touching chemotherapy or contaminated waste.