What Is a Septic Effluent Filter and Is It Necessary?

Posted by
John Woodard on January 26, 2024

When you think of a home septic system, the septic tank or the drainfield likely come to mind. However, there are other components that allow these systems to function at peak efficiency. One of such components is the septic effluent filter. With a properly maintained filter, your septic system can experience a prolonged lifespan compared to those without a filter. In this article, you can learn answers to common questions about septic effluent filters and information about how to maintain your septic system’s filter.

What is a septic effluent filter?

A septic effluent filter is a cylindrical device that blocks solid matter from clogging the output pipe and drainfield in a septic system. The ultimate purpose of an effluent filter is to keep septic wastewater flowing smoothly. It accomplishes this by stopping solid matter from passing through the output baffle and into the drainfield. This creates smoother effluent, the discharged wastewater from the septic tank, and protects the drainfield from solid matter that can clog pipes and thicken the layer of bacteria at the bottom and side of the drainfield. The effluent filter is essentially a strainer that blocks large chunks of debris from passing through. The solid matter that does not make it past the filter is sent back to the bottom of the tank. These solids remain in the tank until they are pumped out. The waste that passes through the filter makes its way to the drainfield, where organic waste is eliminated from the wastewater.

Learn more: What is a septic tank and how does it work?

septic tank diagram

Is a septic effluent filter necessary?

In many counties, effluent filters are required by local codes in any septic system. Even in areas where effluent filters are not required, they can greatly extend the lifespan of your system. Adding a filter to your tank will only help prevent issues with your system over time. Septic tanks collect all wastewater from a home. Many of the solids in this wastewater cannot be processed by the bacteria in the tank itself. Because these solids cannot be broken down, they must remain in the tank to prevent clogging in the drainfield. The effluent filter prevents these solids from flowing through the output pipe and into the drainfield. If these objects enter the pipes, they can clog, causing sewage to back up into the home or pool by the septic tank.

Without an effluent filter, your septic system may require exceedingly expensive repairs. A septic filter also prevents the contamination of groundwater and nearby surface water. This makes it not only practical and economical for the purposes of your septic system, but also environmentally friendly.

How long do septic effluent filters last?

Septic effluent filters do not work for a set amount of time. Rather, they should be replaced when they sustain damage that compromises their ability to filter solid matter from wastewater. You should always inspect the effluent filter for damage when you spray the filter off during routine maintenance. This can be as little as once every 3 to 5 years or more frequently depending on need. You may also need to replace the effluent filter if the filter is not full and you notice clogging in the output baffle of your septic tank.

How to prevent an effluent filter from clogging

If maintained well, a septic effluent filter should not clog before its usual cleaning timeframe. However, there are many precautions homeowners can take to prevent their septic filters from becoming overwhelmed.

  • Don’t use too much water at once. If your home uses too much water at once, the septic tank can become overwhelmed, causing solids to clog up the effluent filter.
  • Don’t put solids down your drains. While the purpose of effluent filters is to filter out solids, too many solids in the septic tank increase the chances of the filter clogging. Homes with a garbage disposal should be particularly cautious about subjecting their system to too many solids.
  • Don’t flush the wrong things down the toilet. Toilet paper is the only appropriate man-made substance that should be flushed down the toilet. Beware of “flushable wipes” that claim they are not harmful to flush. In reality, these do not break down in water and can clog up an effluent filter quickly.
  • Don’t drain harmful cleaning agents. Some cleaning supplies can damage the microbiome at the bottom of a septic tank. Without these bacteria, solids are not broken down properly, and they can clog the effluent filter. To prevent these bacteria from dying, avoid cleaning your toilet or sinks with antibacterial cleaners, bleach, or chemical drain cleaners.

How do I access my septic effluent filter?

Septic effluent filters are located in the baffle pipe inside the septic tank, so they can only be accessed by opening the tank itself. You can open the septic tank’s lid with a screwdriver or a prybar depending on the material of the access lid. If your septic tank does not have an access riser, the surface above the tank must be dug up to allow access. However, all modern septic installations should contain an access riser.

Learn more: What is a septic tank riser kit and is it necessary?

How often to clean a septic effluent filter

At the very least, a septic effluent filter should be cleaned every time your tank is emptied, normally once every 3 to 5 years. This is the perfect time to take out the filter because it ensures that no solid matter will make it to the output while the filter is not present. In most cases, an effluent filter should be cleaned more often than once every 3 to 5 years. In fact, depending on the size of your home, you may need to clean the filter at least once every 6 months. If you notice your septic system backing up regularly, cleaning your effluent filter more frequently can resolve the problem.

How to clean a septic effluent filter

Cleaning a septic effluent filter is simple, but it requires a few precautions to be made. Whenever you open the access hole to your septic tank, you must take all necessary measures to ensure that no children, animals, or harmful objects will fall into the tank. This may look like a traffic cone, a barricade, or any other measure you deem necessary. Since the contents inside septic tanks are not sanitary, ensure you equip yourself with a mask and gloves before beginning. Follow these steps to clean your septic system’s effluent filter:

  1. Remove the tank’s lid. Most septic systems have a riser connected to the tank to allow easy access. You will need either a screwdriver or prybar to open the lid to most septic tanks. If your septic tank does not have a connected riser, the surface above the tank must be dug up to allow access.
  2. Take out the effluent filter. The filter will be connected to the baffle pipe near the tank’s output. Remember to wear a mask and gloves.
  3. Spray the filter. Take the filter away from any other people, animals, or objects that you do not want contaminated. Spray the filter down with a hose until there are no solid objects remaining. It is recommended you wear safety goggles while spraying an effluent filter to protect your eyes from contamination.
  4. Inspect the filter for damage. Once the filter is clean, you should inspect it for any damage that could compromise its filtration capabilities. If you notice damage, the filter should be replaced.
  5. Put the filter back. Once you ensure the filter is not damaged, you can place it back into the baffle pipe.
  6. Close the access lid. Ensure that the access lid is secure and cannot be opened without the proper equipment.

Learn more: How to maintain your septic system


If you have any additional questions, please do not hesitate to contact us.

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