Septic Effluent Filter Cleaning (Safety & Step-by-Step Guide) | Waukesha, WI

Why Effluent Filter Cleaning Matters

Your effluent filter traps solids before they reach the drainfield. When it clogs, the tank level rises and can back up into the building. Routine inspection and cleaning extend the life of your POWTS and help prevent costly drainfield failures. (See also Wisconsin POWTS maintenance standards.)

Pro tip: Have the tank pumped right before cleaning the filter. This lowers the water level and makes cleaning safer and faster.

Where the Filter Is Located

The filter sits in the outlet baffle/housing of your septic tank, typically under the second manhole cover on a two-compartment tank (or the second tank on a two-tank system). Most residential covers are concrete and ~24–28 inches in diameter.
Why this layout? Modern tanks use baffles/filters to keep scum and solids from reaching the drainfield. 

Step-by-Step: How to Clean the Filter (Outside the Tank Only)

• Stage the hose & remove the cover carefully. Check the water level in the tank.

• If water is below the top of the filter housing: Pull up on the filter handle and remove the filter from the housing.

• If water is above the top of the housing/outlet pipe: Lift slowly in small increments until you hear water exiting the tank; pause at that level until the water drops below the top of the housing—then remove fully.

• Rinse the filter inside the riser. Hold the filter within the manhole riser and spray it back into the tank until visually clean (see your figures 1–3).

• Reinsert gently. Align the filter over the housing and let gravity seat it (do not force). With a pumped/empty tank, it usually drops into place; with a full tank, apply only light pressure to start, then let it seat as it breaks the water surface (see figure 4).

• Replace and secure the cover. Lock/secure to prevent unauthorized access.

How Often Should I Clean the Filter?

Frequency varies by household size, usage, and tank design. At minimum, clean the filter whenever the tank is pumped; many households benefit from annual checks, and new installs may need 30–60 day checks until a pattern is established. EPA-aligned guidance commonly cites every 3–5 years for pumping, with filter cleaning performed at the same visit—more often if you notice slow drains or rising tank level.

Rule of thumb (your original guidance, kept):

• One single-chamber tank: check every 30–60 days to establish a pattern.

• Two-compartment or two-tank systems: check at least every 6 months (some cases every 4–5 months) until frequency is established.

Safety First

• Never enter a septic tank. Only trained crews with confined-space procedures/equipment may do so. 

• If you see standing water over lids, damaged lids, strong sewer gas, or active backup, call a professional immediately.

• For Wisconsin design/maintenance standards, see SPS 383 and the POWTS Inspector’s Handbook.

Need Help?

Not sure about your setup or filter style? Call Herr Construction at 262-968-2550 or request service online.

Frequency of cleaning: The frequency at which an effluent filter should be cleaned is going to vary for every system. It is imperative that if the water level in the septic tank begins to rise above the filter housing, the filter should be cleaned promptly. Once the level in the tank begins to rise above the filter housing, the potential for a backup into the building begins to increase. In a system with only one (one-chamber) septic tank, it is recommended that you check the water level every 30 to 60 days until a pattern is established. A system with a two-compartment tank , or a system with two septic tanks, should be checked at least once every six months (in some instances every four to five months) until a frequency is established.