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How often do you need to pump a grease trap?
Short answer: whatever your local sewer authority says, and usually before grease and solids fill a quarter of the trap. There is no single national schedule. The most common rule in city FOG ordinances is the 25% rule: the trap or interceptor must be pumped before the floating grease plus settled solids reach 25% of its liquid depth or capacity. Many cities pair that with a maximum interval, commonly every 90 days for large outdoor (gravity) interceptors and more often (often monthly or weekly) for small under-sink (hydromechanical) traps.
What drives the schedule
- Trap size vs. kitchen volume. A small under-sink trap in a busy kitchen can hit 25% in days; a large in-ground interceptor may last months.
- Your city's maximum interval. Even if the trap is under 25%, many ordinances require a full pump-out at a fixed interval.
- Approved haulers and manifests. Many programs require a registered or permitted pumper and a signed manifest for each service, kept on site for inspection.
- Variances. Some programs let you extend the interval if inspections show low accumulation; others shorten it after a violation.
What cities actually require (quoted)
| City | Pumping rule, quoted from the official source |
|---|---|
| Phoenix, AZ | A full cleaning is required when FOG and solids occupy more than 25% of the interceptor's capacity; no hydromechanical interceptor may go more than 90 days without maintenance. |
| Elgin, IL | Interceptor-style systems must be cleaned at least once every 90 days and trap-style systems at least once a month, or more often as needed. |
| Joliet, IL | At a minimum, grease interceptors must be cleaned every 90 days and grease traps once per week. |
| Springfield, IL | Grease traps: cleaning intervals may not exceed 30 days (unless a variance is granted). Grease interceptors: cleaning intervals may not exceed 90 days. |
| New Orleans, LA | Interceptors must be fully evacuated at least every 90 days, and within 2 working days whenever 25% or more of the design capacity (bottom to outlet invert) holds grease, solids or floating material (SWBNO Plumbing Code §16.5). |
| New York, NY | Minimum cleaning frequency: accumulated fat, oil, grease and solids must not exceed 25% of the device's designed total liquid depth (15 RCNY §19-11(q)). |
| Dallas, TX | Food service establishment grease traps must be 100% pumped out the earlier of every 90 days, or when 25% or more of the wetted height is floating material, sediment, oil or grease. |
| Houston, TX | Every interceptor inside city limits must be fully evacuated at least quarterly (every 90 days) unless a Notice of Waiver is submitted and approved (City Code §47-512(b)). |
| San Antonio, TX | An FSE whose interceptor contents reach 25% or more of the wetted height during a SAWS inspection is considered in violation. |
| Little Rock, AR | 8 Each FSE shall cooperate with LRWRA to determine the frequency at which their Grease 9 Trap shall be Evacuated, but all Grease Traps shall be opened, inspected, Evacuated and 10 maintained at a minimum of once per week. |
| Flagstaff, AZ | 5.8.3 The maximum amount of time between pump outs for a grease interceptor with liquid volume greater than 500 gallons shall be no more than 90 days. |
| Gilbert, AZ | At a minimum, the entire contents shall be removed every six months, or more frequently as needed to prevent carry over of grease into the POTW, unless it can be demonstrated to the satisfaction of the director that the pumping frequency can be extended past the six-month period. |
| Tucson, AZ | Hydromechanical grease interceptors must be cleaned at least monthly. |
| Sacramento, CA | The grease interceptor should be pumped completely every three months. |
| San Francisco, CA | Within 30 days of the official transfer of ownership, the new owner shall apply for a Food Service Establishment Wastewater Discharge Permit, or other authorization, as required by the Department rules and regulations. |
| Stockton, CA | Grease interceptors shall be fully pumped out and cleaned once every three months or when the combined FOG and solids accumulation in the grease interceptor equals 25 percent of the design hydraulic depth of the grease interceptor, whichever occurs first. |
| Colorado Springs, CO | Clean the grease interceptor based on the “25% Rule”. |
| Denver, CO | Gravity grease interceptors should be pumped and cleaned before the FOG and solids level reach 25% of the total liquid capacity of the interceptor. ii. |
| Washington, DC | Gravity Grease interceptors: Shall be cleaned and inspected every 90 days or less if the grease interceptor becomes more than 25% full of Grease and Solids. |
| Savannah, GA | Maintenance of grease interceptors must include thorough pump-out and/or cleaning as needed, (whenever 25% or more of the grease trap becomes full of grease and/or solids as determined by the measured depth), with a minimum frequency of four (4) times per year. |
| Aurora, IL | At a minimum, interceptor-style GRS shall be cleaned at least once every 90 days and trap-style GRS cleaned at least once per week. |
| Edwardsville, IL | Dunlap Lake grinder pump fees shall be $5.00 per month. |
| Glen Ellyn, IL | At a minimum, a gravity grease interceptor shall be cleaned at least once every 90 days and hydro-mechanical FOG recovery system shall be cleaned at least once every 30 days. |
| Oak Lawn, IL | All food service facilities shall have monthly pest control conducted by a licensed rodent and pest control company. |
| Oswego, IL | At a minimum, interceptor-style GRS shall be cleaned at least once every 90 days and trap-style GRS cleaned at least once per week. |
| Schaumburg, IL | Clean out and removal shall be done on not less than a monthly basis unless the village determines that less or more frequent maintenance schedule is required to achieve the purposes of this section and to minimize the discharge of a prohibited concentration of fats, oils or grease. |
| Wheaton, IL | Trap-style grease removal systems shall be cleaned no less than every 30 days. |
| Woodstock, IL | A GI located outside an FSE on its property shall be inspected and the grease cap and solids blanket minimally cleaned every three months; the entire contents of the trap cleaned annually; and the GI repaired regularly, as needed, by the Owner at his expense. |
| Indianapolis, IN | Monitoring outside grease traps regularly and cleaning them when FOG reaches 25% of the grease trap depth. |
| Wichita, KS | GI s need to be professionally serviced by a grease hauler at least every three months. |
| Louisville, KY | At no time, shall the cleaning frequency of the grease interceptor exceed 90 days, unless approved by MSD. |
| Baton Rouge, LA | If grease traps are more than 50% full when cleaned weekly, the cleaning frequency needs to be increased. o Witness all grease trap or interceptor cleaning/maintenance activities to ensure the device is properly operating. |
| Boston, MA | Grease traps should be cleaned when 25% of the liquid level of the trap is grease or oil, once a month minimum for point-of-use traps, and quarterly for large in-ground grease interceptors. |
| Kansas City, MO | This rule states that when 25% of a vertical core sample from the. interceptor is filled with solids and grease layers, the interceptor must be cleaned. |
| Omaha, NE | Inside grease traps shall be cleaned as often as necessary but not less frequent than at least every 30 days. |
| Albuquerque, NM | Proper maintenance includes pumping before the total amount of floatable grease and solids constitute 25% of the vertical water column of the trap as measured in the field. |
| Henderson, NV | A sand/oil separator shall be completely pumped and serviced at minimum once per 12 months or more frequently as necessary. |
| Portland, OR | A grease interceptor is out of service for more than 60 days but less than 90 days due to repairs. c. |
| Chattanooga, TN | If the FOG and food solids content of the grease trap are greater than 25%, then the grease trap must be cleaned as frequently as needed to prevent 25% of capacity being taken from FOG and food solids. |
| Nashville, TN | Have grease interceptor pumped/cleaned of complete contents by an Approved Grease Waste Hauler at a minimum of every 90 days. |
See every city on the states page. Rules change; verify with your city.
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