Top 10 Reasons the Effluent Filter Is Plugged

Top 10 Reasons the Effluent Filter Is Plugged

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If an effluent screen seems to need excessive cleaning, it may be that the homeowner has too many solids or chemicals or too much water going down the drains. Here are common causes of premature clogging to warn homeowners against.

1. Large volumes of wastewater generated in a short period of time can result in turbulence in the septic tank and reduced retention time, which can lead to solids plugging the effluent screen. Leaks and large parties are examples of such uses.

2. Large laundry days. Tell homeowners to not do all the laundry in one day. Spread wash loads throughout the week and wash at times when there is not a lot of water being used in the home. Do not run multiple water-using devices at the same time, such as showering or running the dishwasher while doing the laundry.

3. Reroute water treatment devices such as iron filters and water softeners from the septic system. The discharge water from these devices may add extra solids in the case of iron filters and affect settling in the case of softeners.

4. Garbage disposals and dishwashers with food grinders are notorious for adding solids to a septic tank. Minimize the use of the garbage disposal or eliminate its use altogether by placing food scraps into a compost bin or trash can. Some new dishwashers are even equipped with food grinders that act as garbage disposals. To keep solids out of your system, scrape all dishes well before placing them in the dishwasher.

5. Do not dump fats, oils and grease down the drain; instead, put them in the garbage.

6. Washing machines can add a significant amount of lint to the septic tank, which can clog effluent filters. Avoid this by placing a simple lint filter on the end of the outlet hose.

7. Do not use the toilet as a trash can. Nothing other than human waste and toilet paper should be flushed. Do not flush tissues, hygiene products, cigarette butts, etc.

8. Reduce the amount of strong cleaning chemicals and antibacterial soaps used in the home. Bleach and other antibacterial products can kill the beneficial bacteria in the septic tank, reducing the rate of solids decomposition and resulting in more solids for the filter to catch.

9. Do not flush unused or expired medications. These products can kill the beneficial bacteria in the septic tank.

10. Do not use products advertised as septic additives or septic cleaners. These products are not necessary and may kill the beneficial bacteria in your septic tank.

If none of these is the determined cause, it is a good idea to encourage customers to start eliminating various products around the house and replacing them with more natural solutions to see how the effluent filter responds. 

About the author    
Sara Heger, Ph.D., is an engineer, researcher and instructor in the Onsite Sewage Treatment Program in the Water Resources Center at the University of Minnesota. She presents at many local and national training events regarding the design, installation and management of septic systems and related research. Heger is education chair of the Minnesota Onsite Wastewater Association and the National Onsite Wastewater Recycling Association, and she serves on the NSF International Committee on Wastewater Treatment Systems. Ask Heger questions about septic system maintenance and operation by sending an email to


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