Home / Guides / Chicago grease trap additives

Chicago guide

Enzymes, bacteria and grease trap additives in Chicago

By Stew David, GreaseTrapRules · Updated Nov 3, 2026 · Every rule below links to its official source. Rules change; verify with MWRD or the city.

Short answer: the Metropolitan Water Reclamation District (MWRD) bans putting chemical or biological agents into a grease trap to dissolve or emulsify the grease so it flows on into the sewer. Additives do not replace pumping: Chicago code still requires removing the grease and solids as often as needed and keeping a 5-year written log.

What the MWRD ordinance says

MWRD Sewage and Waste Control Ordinance, as amended February 5, 2026, Article III, Section 8 (Uncontrolled or Unregulated Wastes):

"No person shall reintroduce into the sewer system of the District materials which have been removed from the sewer system by catch basins, grease traps, and other pretreatment devices. Physical, chemical or biological agents shall not be introduced into catch basins, grease traps or other pretreatment devices for the purposes of resuspending, dissolving, emulsifying or rendering soluble any pollutants or other materials removed from a waste stream by such pretreatment devices and reintroducing these materials into the sewer system."

Appendix B of the same ordinance lists a maximum of 250 mg/L total fats, oils and greases (FOG) for discharges into sewers under the District's jurisdiction.

What this means in the kitchen

  • If a product's purpose is to dissolve, emulsify or "liquefy" grease so it washes out of the trap, it fits the wording of the ban. If you are unsure about a product, ask MWRD before you use it: (312) 751-5600.
  • Do not pour or pump trap contents back into any drain. Removed grease goes out with your hauler.
  • Pumping is still required. Chicago Municipal Code 18-29-1003.13 says interceptors must be maintained by periodic removal of accumulated grease, scum, oil and solids as often as necessary for efficient operation. Chicago sets no fixed number of days, so your pumper sets the interval.
  • Every cleaning goes in a written log kept for the life of the unit or 5 years, whichever is longer (18-29-1003.13). See Chicago grease trap records.

These are plain-language readings of the quoted text, not a list of approved or banned brands. We do not state fines here because we have not sourced a penalty amount for this section.

Stay on schedule the simple way

Common questions

Are grease trap enzymes or bacteria allowed in Chicago?

MWRD's Sewage and Waste Control Ordinance (as amended Feb. 5, 2026), Article III Section 8, says physical, chemical or biological agents shall not be introduced into grease traps or other pretreatment devices for the purpose of resuspending, dissolving, emulsifying or rendering soluble the materials the trap removed and sending them back into the sewer.

Can an additive replace pumping in Chicago?

No. Chicago Municipal Code 18-29-1003.13 says interceptors must be maintained by periodic removal of accumulated grease, scum, oil and solids as often as needed for efficient operation, and the owner must keep a written maintenance record for the life of the unit or five years, whichever is longer.

What is MWRD's grease limit for sewer discharges?

Appendix B of the MWRD ordinance lists a maximum of 250 mg/L total fats, oils and greases (FOG) for discharges into sewerage systems under the District's jurisdiction.

Can grease from the trap be poured back down a drain?

No. The same MWRD section says no person shall reintroduce into the sewer system materials removed by catch basins, grease traps and other pretreatment devices.

Sources

This guide explains the ordinance text; it is not legal advice.