By Alyssa Gersdorf, Environmental Program Supervisor for the City of Post Falls
Every day in Post Falls and Rathdrum, about 3 million gallons of wastewater leave homes and businesses and begin a journey most people never think about. Whether it’s flushed, washed from showers, or sent down sink drains, everything entering the sewer system follows the same path, and not all of it behaves as expected. It all flows to the Post Falls Water Reclamation Facility (WRF), where the water is cleaned and returned to the Spokane River. While water can be reclaimed; debris, chemicals, and slow‑to‑break‑down materials each have their own fate.
A water reclamation facility is like a living ecosystem. Billions of microorganisms break down organic material so the water can be safely returned to the river. These microbes thrive on what they’re meant to receive: human waste, toilet paper, and small amounts of soap, food residue, and household products that naturally wash down drains. When the waste stream stays within this design, solids settle out, organic matter is broken down, and the cleaned water is disinfected before flowing back to the Spokane River.
Many items entering the sewer system don’t behave the way people expect. They may clog equipment, disrupt the biological treatment process, or pass through the system and risk reaching the river. And in many cases, they’re already causing blockages in the collection system long before they reach the plant.
Physical materials are the most visible problem. Wipes, including those labeled “flushable”, stay intact and tangle in pumps. Plastics, wrappers, and hygiene products never break down and must be screened out and landfilled. Sand, gravel, and other debris settle in pipes and basins, reducing capacity and wearing out equipment. Even fats, oils, and grease harden into blockages that can cause backups. At the headworks, a screen captures anything larger than one‑eighth of an inch, but it’s only a protective barrier, not a license to send trash down the drain.
Chemical contaminants create a different challenge. Paints, solvents, and household chemicals can kill the microorganisms responsible for breaking down organic material and removing nutrients. Medications often pass through treatment unchanged and can affect aquatic life once they reach the river. Some products also release persistent toxins, such as Polychlorinated biphenyls (PCBs) and Per- and polyfluoroalkyl substances (PFAS), that don’t break down during treatment and can build up in the environment, creating long term risks for water quality and the watershed. As new contaminants emerge, treatment technologies evolve. The WRF meets today’s requirements, and smart choices at home help limit the need for more complex and costly treatment down the road. Chemicals and medications should be disposed of at a hazardous waste facility or through a medication take back program, in which they are incinerated.
Even products labeled “biodegradable” or “compostable” can cause problems. Items like compostable wipes, paper towels, and plant‑based products may break down eventually, but not fast enough for a treatment plant. In the short term, they behave like plastics and must be screened out and hauled away.
Protecting our waterways and in this case, the Spokane River, is something our whole community can take part in. Thoughtful choices at home such as avoiding wipes and grease, keeping chemicals and medications out of the drain, and using local hazardous waste programs can help safeguard the treatment process and the river that connects us all. Every non‑flushable item adds cost, energy use, and operational strain, and increases the risk that pollutants will reach the river. With the Spokane River’s nutrient‑sensitive conditions and strict phosphorus limits, understanding the fate of what we send down the drain is one of the most effective ways we can protect the WRF, the river, and the watershed we share.
Remember; to protect the system, only human waste and TP in the drain. Anything else, please refrain!
