How to Clean and Service a Septic Filter

By Michael Franco

March 11, 2025

Maintaining your septic system is critical to keeping your household plumbing running smoothly. One of the most important components of a septic system is the septic tank filter, which helps prevent solid waste from entering and clogging the drain field.

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The drain field, also known as a leach field, is a vital part of the septic system that disperses treated wastewater into the soil. It consists of a series of perforated pipes laid in gravel-filled trenches, allowing the water to gradually seep into the ground. When the drain field becomes clogged by solids, it can lead to wastewater backups and unpleasant odors.

Ensuring that your septic tank filter remains clean helps protect the drain field and keeps the entire system functioning efficiently.

While this maintenance task is generally best carried out by a professional due to the risks of contamination from human waste, an intrepid homeowner could tackle it themselves with the right precautions and knowledge. Here's everything you need to know about septic tank filters and how to clean them.

What Is a Septic Tank Filter?

A septic tank filter is a crucial part of your septic system, designed to trap solids and prevent them from escaping into the drain field, where they can cause costly blockages or damage. Typically made of plastic, the filter is a mesh sleeve that's installed in the outlet baffle inside the septic tank.

Is a Septic Filter Required by Law?

Whether a septic tank filter is required by law depends on local building codes and regulations. In many jurisdictions, septic tank filters are mandated in new installations to ensure better system performance and longevity. Even if not legally required, having a filter is highly recommended because it extends the life of your septic system by preventing solids from clogging your drain field.

Where Is My Septic Tank Filter Located?

Your septic tank filter is located inside the outlet baffle of the septic tank. The outlet baffle is usually situated at the far end of the tank, where treated wastewater exits the tank and flows into the drain field.

To access the filter, you'll need to locate the septic tank lid and remove it. If you're unsure of the exact location of your septic tank, consult a site plan of your property or contact a professional septic service provider.

How to Clean and Service Your Septic Tank Filter

Tools and Materials Needed:

Protective gloves
Safety goggles
Face mask
Cleaning brush
Garden hose with spray nozzle
Bucket
Long-handled screwdriver or pry bar (if needed to open the tank lid)
Clean water source (if hose not available)

Step-by-Step Instructions:

Step 1: Get Prepared

Don your mask, goggles and gloves.

Step 2: Locate and Open the Septic Tank Lid

First, find the septic tank lid, which is usually buried a few inches below the ground. Use a long-handled screwdriver or pry bar to carefully lift the lid. Be cautious, as opening the septic tank exposes you to potentially harmful gases.

Step 3: Remove the Filter

Once the lid is off, locate the outlet baffle, which houses the filter. Carefully pull the filter out of the baffle. Be prepared for the filter to be coated with waste solids and debris.

Step 4: Clean the Filter

Holding the filter over a bucket, use a garden hose with a spray nozzle to rinse off the solids. Spray from the top down to avoid splashing yourself. If solids are stubborn, use a cleaning brush to scrub away buildup.

Step 5: Inspect the Filter and Baffle

After cleaning, inspect the filter for damage or excessive wear. Check the outlet baffle for blockages or buildup and clean it if necessary. If the filter appears damaged, replace it with a new one.

Step 6: Reinstall the Filter

Once the filter is clean and inspected, carefully reinstall it in the outlet baffle. Ensure it is seated securely to prevent it from dislodging during operation.

Step 7: Close the Septic Tank Lid

Replace the septic tank lid securely to prevent unauthorized access and protect against accidental falls. Ensure the lid is flush with the ground to avoid creating a tripping hazard.

How Often Should You Clean Septic Tank Filters?

Septic tank filters generally need to be cleaned whenever you have your septic system pumped, approximately every three to five years. However, you might need to increase that frequency to every six to 12 months, depending on the size of your household, water usage and how much solid waste your septic system processes.

If you notice slow drains, gurgling noises in your plumbing or sewage odors near the drain field, these could be signs that your filter needs more frequent cleaning.

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Avoiding Septic System Filter Clogging

Preventing filter clogs is primarily about managing what goes down your drains. Here are some tips:

Minimize Solid Waste: Use a garbage disposal sparingly, and avoid flushing non-biodegradable items like wipes, sanitary products or paper towels.
Avoid Pouring Grease Down the Drain: Grease and oils can solidify and create clogs.
Use Water Efficiently: Excessive water usage can overload the septic system, increasing the likelihood of solids floating up and clogging the filter.
Schedule Regular Maintenance: Regular septic tank pumping and inspections can help identify potential problems before they become serious.

Final Thoughts

While cleaning a septic tank filter is a task that many homeowners can manage, it's not without risks. Handling human waste and exposure to harmful bacteria and gases can be hazardous without proper safety precautions. For this reason, professional septic service is recommended.

However, if you're up for the challenge, armed with the right tools, protective gear and a solid understanding of the process, cleaning your septic tank filter can be a manageable DIY project that helps prolong the life of your septic system and prevent costly repairs.

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