Tips for Proper Effluent Screen Cleaning

Tips for Proper Effluent Screen Cleaning

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An effluent screen requires regular maintenance and must be periodically checked. The need to clean a screen should not be considered an indication of a problem since the purpose of a screen is to catch suspended solids.

As a concern for the homeowner’s safety in dealing with the components of a septic system, it is recommended that a certified inspector or septic tank pumper/maintainer or service provider provide this maintenance, but some property owners might clean their own screen. The screen must be periodically removed from the tank, and the solids that have been trapped and attached to the screen must be washed back into the septic tank.  

For this reason, it is more appropriate to have this maintenance done when the septic tank is being pumped so those solids can be removed, but the filter may need to be cleaned more frequently than the tank is cleaned, and therefore, it must be done properly. In most cases, the effluent screen is cleaned when the tank is pumped, but it should be inspected at a frequency of at least every six months to two years, depending on the filter and use of the system.

Factors that can increase the frequency of maintenance include:

  • High content of fats, oil and grease
  • Presence of hair or laundry lint
  • Presence of excessive solids through use of a garbage disposal or excessive toilet paper
  • High water usage and peak flows
  • Number of people in the home
  • Size of the septic tank and effluent screen 

Effluent screen cleaning procedure

1. Do not enter the septic tank for any reason. Noxious gases exist in septic tanks and can result in serious injury or death. You do not need to enter the tank in order to clean the screen. If the tank is deep, the effluent screen should have a handle on it to remove the screen without placing your head below the top of the tank maintenance hole.

2. Put on waterproof, disposable gloves and safety glasses. The effluent screen should be located below a large-diameter access (20 inches), but it is possible only a 6-inch access exists. Remove the maintenance hole cover of the septic tank and note the liquid level in the tank. The liquid level should be at the bottom of the outlet pipe. If it is below the outlet pipe, this is a sign that the tank is not watertight and you will have to troubleshoot the problem. If the liquid level is above the outlet pipe or the effluent screen, do not remove the screen. This is a sign of problems somewhere in the system: a plugged screen, pump failure, plugged soil treatment area, etc. Pump the tank before removing the screen. This will prevent a surge of excess effluent, containing unwanted solids, from moving into the next component of the treatment system.

3. If the liquid level is at the bottom of the outlet pipe, carefully remove the screen from its casing to prevent collected solids from falling off the screen. (Some screens have a secondary device to prevent solids bypass.) Note the condition of the screen and the extent of buildup, as this will impact the frequency of cleaning needed. Using a garden hose, spray off the screen over the first septic tank maintenance hole or place the screen in a 5-gallon bucket and spray off all material into the bucket. Be careful to prevent splashing onto your body or clothes or into the yard. Do not clean the effluent screen in the grass next to the septic tank; raw sewage in the yard is a public health hazard. Never allow the screen cleanings to be left on the ground.

4. Return the screen to its casing once it has been cleaned. Dump the contents of the bucket into the septic tank and add a small amount of bleach and rinse the bucket several times (emptying the rinse water into the septic tank each time.) Secure the maintenance hole cover once you are finished. The solids from the screen cleaning will settle and get removed the next time the tank is pumped during routine maintenance. Make sure the screen is reinstalled correctly to ensure proper operation.

5. Once the job is complete, dispose of the gloves and wash your hands thoroughly with soap and hot water. If your clothes were contaminated, remove them immediately and launder in hot water.

If there is premature clogging (less than six months), it may be an indicator of problems such as: 

  1. Excessive chemical usage
  2. Reduced detention time due to excessive flows
  3. Neglecting to pump out the septic tank as needed 
  4. Excessive flushing of grease or oil down the kitchen drain 
  5. Use of a garbage disposal
  6. Excessive toilet paper use, along with disposal of other sanitary products not advisable for flushing

If a screen requires servicing more frequently than anticipated by design, either the effluent screen or the wastewater characteristics should be evaluated to find the cause for premature clogging. This may indicate leaks in the fixtures, excess water use, poor wastewater quality or an inadequately sized screen for the needed application.

About the author: Sara Heger, Ph.D., is a researcher and educator in the Onsite Sewage Treatment Program in the Water Resources Center at the University of Minnesota, where she also earned her degrees in agricultural and biosystems engineering and water resource science. She presents at many local and national training events regarding the design, installation and management of septic systems and related research. Heger is president-elect of the National Onsite Wastewater Recycling Association, and she serves on the NSF International Committee on Wastewater Treatment Systems. Ask Heger questions about septic system design, installation, maintenance and operation by sending an email to


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