Updated October 2026. Cleaning steps from the Greene County, Ohio health district; intervals from local health and university guidance.
To clean a septic tank effluent filter, open the outlet riser, pull the filter out of the outlet tee, hose the solids back into the tank, check it for damage, and put it back the way it came out. Local guidance on how often ranges from every 3 to 6 months (Greene County, Ohio) to every 6 months to 2 years (University of Rhode Island). A safe rule is to check it at least once a year and clean it every time the tank is pumped.
What is an effluent filter?
An effluent filter, also called an outlet filter, is a slotted plastic cartridge that sits inside the outlet tee at the drainfield end of the septic tank. Liquid from the clear middle layer passes through the slots, while hair, lint, grease and small solids stay in the tank. The University of Rhode Island recommends one as an added layer of protection for the drainfield.
Not every tank has one, especially older systems. If you are not sure, your pumper can tell you at the next pumping, and a filter can usually be added to an existing outlet. See are septic tank filters necessary?
How to clean a septic tank effluent filter
These steps follow the Greene County Combined Health District’s instructions:
- Put on disposable gloves. Wear eye protection if you will be spraying.
- Open the outlet riser. Unscrew or unlatch the lid over the outlet end of the tank. Never lean into or enter the tank; septic gases can be deadly.
- Pull the filter out of the tee. Lift it by its handle, or hook it with a small hoe or rake. Hold it over the tank opening as it comes out.
- Hose it off over the tank. Spray the slots with a garden hose and nozzle so the solids rinse back into the tank, not onto the yard.
- Inspect it. Look for cracks, broken slots or a damaged handle. Replace the cartridge if it is damaged.
- Reinstall it the same way. Many filters have an arrow that must point toward the outlet pipe. Seat it fully in the tee.
- Close and secure the lid. A loose lid is a fall hazard for children and pets.
If the filter is heavily caked after only a few months, the tank probably needs pumping, or too much grease or lint is going down the drains.
Filter clogged again or drains backing up?
A filter that clogs quickly usually means the tank needs pumping. Talk to a local septic company about pumping and a filter check.
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How often should you clean an effluent filter?
| Source | Recommended interval |
|---|---|
| Greene County Combined Health District, Ohio | Every 3 to 6 months |
| University of Rhode Island onsite wastewater program | Typically every 6 months to 2 years |
| Town of Avon, Massachusetts | At least once a year, or as your pumper recommends |
Large households, homes with garbage disposals and homes that do a lot of laundry need more frequent cleaning. Clean the filter every time the tank is pumped, and ask the pumper how dirty it was so you can set your own schedule.
Signs your effluent filter is clogged
- Slow drains or gurgling throughout the house, especially after laundry
- Sewage backing up into the lowest drain or toilet
- A filter alarm going off, on systems that have one
- Water standing above the outlet when the lid is opened
A clogged filter is doing its job, but it has to be cleaned before it backs the tank up. For other causes of a backup, see how to know if your septic tank is full.
Best septic tank effluent filters
If your tank has no filter or the old one is broken, these are the common replacements. Match the filter to your outlet pipe size (most homes use 4 inch) and your daily flow, and ask your pumper if you are unsure.
| Filter | Type | What the maker says | Best for |
|---|---|---|---|
| Polylok PL-68 filter and housing | Slotted cartridge with housing | 1/16-inch slots; maker rates it for residential flows up to 800 gallons per day | Most homes; replaces a standard outlet tee |
| Polylok PL-122 filter and housing | Slotted cartridge with housing | Maker rates it up to 3,000 gallons per day; flow-control ball stops flow when the filter is pulled; optional alarm switch | Larger homes or anyone who wants an alarm |
| Tuf-Tite EF-4 combo | Slotted cartridge with tee | Fits 4-inch SCH40 pipe, with an adapter ring for thin-wall SDR35 | Retrofitting a common 4-inch outlet |
| Tuf-Tite EF-6 combo | Slotted cartridge with sanitary tee | Filters solids down to 1/16 inch; includes tee and bushing | Higher flow or commercial use |
| SimTech STF-110 | Bristle filter | Fits an existing 4-inch pipe or baffle; maker rates it up to 1,200 gallons per day | Cheapest retrofit; disposable |
| Zoeller 170-0078 | Two-piece cartridge | 15 inches tall; fits 4-inch pipe; two-piece design keeps unfiltered effluent from passing when the cartridge is pulled | Zoeller systems and simple swaps |
As an Amazon Associate we earn from qualifying purchases. Specs come from each maker or its Amazon listing; we have not tested these filters.
Slotted vs bristle filters
| Slotted cartridge (Polylok, Tuf-Tite, Zoeller) | Bristle filter (SimTech) | |
|---|---|---|
| How it filters | Fine slots, often 1/16 inch | Dense plastic bristles |
| Cleaning | Hose off and reuse | Hose off, or replace |
| Cost | Higher | Lower |
| Best for | Long-term installs and new tanks | Quick, low-cost retrofit into an existing tee |
Quick answers
Where is the effluent filter in a septic tank?
In the outlet tee at the end of the tank that leads to the drainfield, usually under its own riser and lid.
Can I clean the effluent filter myself?
Yes, if you can reach it safely from ground level with gloves on. Never put your head or body into the tank. Many owners have the pumper clean it during each pumping.
What is a final effluent filter?
It is another name for the outlet filter at the end of the septic tank, the last screen before effluent goes to the drainfield or pump chamber.
Can I remove the effluent filter if it keeps clogging?
No. A filter that clogs often is catching solids that would otherwise plug the drainfield, which is far more expensive to fix. Some local codes also require an outlet filter on new tanks. Have the tank pumped and ask your septic company why it is clogging so fast.
Does an effluent filter replace pumping?
No. It keeps small solids in the tank, but the tank still fills with sludge and needs pumping, every 3 to 5 years for most homes according to the EPA.
Sources
- Greene County Combined Health District, Ohio, How to clean your septic tank filter (PDF)
- University of Rhode Island Onsite Wastewater Training Center, Conventional system fact sheet (PDF)
- Town of Avon, Massachusetts, How do I maintain my septic system effluent filter?
- U.S. EPA, How to care for your septic system