What Is a Septic Effluent Filter?

An effluent filter (Florida's rules call it an outlet filter device) is a filter fitted inside the last septic tank compartment or just after it. It catches small solids in the liquid leaving the tank so they do not travel on to the drain field.

Explanation

The tank lets solids settle as sludge and scum, but some small particles stay in the liquid. A filter at the outlet holds them back. Florida's sizing rule (Rule 62-6.008(2), F.A.C.) says "the use of an approved outlet filter device shall be required" for septic tanks. Under that rule:

• The filter goes inside or after the last tank or tank compartment, before the effluent reaches the drain field.
• It must be placed so it can be reached for routine maintenance.
• Size and installation follow the manufacturer's instructions.
• The requirement covers blackwater tanks, not graywater tanks, laundry tanks or grease interceptors.

Not every tank has one. On a tank outlet without an approved filter, the tank standards (Rule 62-6.013(2)(e)) call for a solids deflection device instead. Where a pump sits inside the tank in a pump chamber insert, the insert's filter counts as the outlet filter.

Good news if your tank has no filter: Florida's definition of repair says installing an approved outlet filter device, where the drain field is not disturbed, is not a repair (Rule 62-6.002(51)). Ask your septic company whether one fits your tank.

Filters need upkeep. The EPA notes that an effluent filter "may also require frequent maintenance and should be included in the inspection and maintenance activities." Ask whether filter cleaning is included in the pumping price. If it is not, published ranges put it at about $100–$200.

When to seek help

• Drains are slow or the plumbing gurgles, which the EPA lists among septic warning signs.
• Your last pump-out report does not say whether the filter was cleaned.
• You do not know whether your tank has a filter. Ask at the next pump-out.

Learn more in what happens during a septic pump-out and how often to pump a septic tank in Florida. Check line items with the septic quote comparison tool, or compare septic pumping companies.

Related terms

• Baffle
• Sludge and scum layers
• Riser
• Drain field (leach field)