CPC · California Plumbing Code
Grease interceptors, FOG systems, and sizing
This hub summarizes CPC requirements for grease interceptors and FOG disposal systems, explains where to find sizing rules (§1014.2.1, §1014.3.6) and performance/installation criteria (§1015).
Last reviewed: July 6, 2026
Overview
This section of the California Plumbing Code covers grease interceptors (gravity and hydromechanical), FOG (fats, oils, and greases) disposal systems, referenced standards, installation location and access, maintenance, and the rules used to size equipment for commercial food‑service and related facilities. The general requirements and definitions are found in Chapter 10 (see §1014 and the definition of Gravity Grease Interceptor) .
Sizing and application rules distinguish hydromechanical (GRD) sizing by certified gpm and fixture load (§1014.2.1 and Table 1014.2.1) and gravity interceptor sizing by drainage fixture units and retention time (§1014.3.6 and Table 1014.3.6). The code also adds performance and installation criteria for engineered FOG disposal systems in §1015 (including a 100 mg/L effluent limit and manufacturer‑based sizing/installation) .
The Code references specific consensus standards for interceptors and FOG equipment (see Table 1009.1 and the referenced standards list) and gives the Authority Having Jurisdiction discretionary authority over required pretreatment, location, and maintenance programs .
In this section
Code references
Grounded in the retrieved California Plumbing Code — click a citation to read the verbatim passage:
CPC § 1014.3.6 High relevance — show source text
Rounded up to nominal interceptor volume. 3 Where the flow rate of directly connected fixture(s) or appliance(s) have no assigned DFU values, the additional grease interceptor volume shall be based on the known flow rate (gpm) (L/s) multiplied by 30 minutes.
EXAMPLE 1014.3.6
GRAVITY GREASE INTERCEPTOR SIZING EXAMPLE
Given: A restaurant with the following fixtures and equip ment.
One food preparation sink; three-floor drains - one in the food prep area, one in the grill area, and one receiving the indirect waste from the ice machine and a mop sink.
Kitchen Drain Line DFU Count (from Table 702.1):
3 floor drains at 2 DFUs each = 6 DFUs
Mop sink at 3 DFUs each = 3 DFUs
Food prep sink at 3 DFUs each = 3 DFUs
Total = 12 DFUs
Using Table 1014.3.6, the grease interceptor will be sized at 750 gallons (2389 L).
1015.0 FOG (Fats, Oils, and Greases) Disposal Sys- tem.
1015.1 Purpose. The purpose of this section is to provide the necessary criteria for the sizing, application, and installation of FOG disposal systems designated as a pretreatment or discharge water quality compliance strategy.
TABLE 1014.3.6
GRAVITY GREASE INTERCEPTOR SIZING
2025 CALIFORNIA PLUMBING CODE 199
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TRAPS AND INTERCEPTORS
1015.2 Components, Materials, and Equipment. FOG disposal systems, including components, materials, and equipment necessary for the proper function of the system, shall comply with ASME A112.14.6. 1015.3 Sizing and Installation. FOG disposal systems shall be sized and installed in accordance with the manufac turer’s installation instructions.
1015.4 Performance. FOG disposal systems shall produce an effluent quality not to exceed 5.84 grains per gallon (gr/gal) (100 mg/L) FOG. 1015.5 [OSHPD 1, 1R, 2, 3, 4 & 5] Grease interceptors shall not be installed in food preparation area of kitchens. 1015.6 [OSHPD 1, 1R, 2, 3, 4 & 5] Grease interceptors shall be installed outside of the kitchen area in location affording ease of maintenance and servicing.
1016.0 Sand Interceptors.
1016.1 Discharge. Where the discharge of a fixture or drain contains solids or semi-solids heavier than water that would be harmful to a drainage system or cause a stoppage within the system, the discharge shall be through a sand interceptor. Multiple floor drains shall be permitted to discharge into one sand interceptor. 1016.2 Authority Having Jurisdiction. Sand interceptors are required where the Authority Having Jurisdiction deems it advisable to have a sand interceptor to protect the drainage system. 1016.3 Construction and Size. Sand interceptors shall be built of brick or concrete, prefabricated coated steel, or other watertight material. The interceptor shall have an interior baffle for full separation of the interceptor into two sections.
CPC § 1011.0 High relevance — show source text
1010.4 Horse Meat and Pet Food
Establishments . . . . . . . . . . . . . . .197
1010.5 Draining and Plumbing . . . . . . . .197
1011.0 Minimum Requirements for Auto Wash Racks . . . . . . . . . . . . .197
1011.1 General . . . . . . . . . . . . . . . . . . . . .197
1012.0 Commercial and Industrial
Laundries . . . . . . . . . . . . . . . . . . .197
1012.1 General . . . . . . . . . . . . . . . . . . . . .197
1013.0 Bottling Establishments . . . . . . . .197
1013.1 General . . . . . . . . . . . . . . . . . . . . .197
1014.0 Grease Interceptors . . . . . . . . . . .197
1014.1 General . . . . . . . . . . . . . . . . . . . . .197
1014.2 Hydromechanical Grease Interceptors . . . . . . . . . . . . . . . . . .198
Table 1014.2.1 Hydromechanical Grease Interceptor Sizing Using Gravity Flow Rates . . . . . . . . . . . .198
1014.3 Gravity Grease Interceptors . . . . .198
Table 1014.3.6 Gravity Grease Interceptor Sizing . . . . . . . . . . . . . . . . . . . . . .199
1015.0 FOG (Fats, Oils, and Greases) Disposal System . . . . . . . . . . . . . .199
1015.1 Purpose . . . . . . . . . . . . . . . . . . . .199
1015.2 Components, Materials, and Equipment . . . . . . . . . . . . . . . . . .200
1015.3 Sizing and Installation . . . . . . . . .200
1015.4 Performance . . . . . . . . . . . . . . . . .200
1016.0 Sand Interceptors . . . . . . . . . . . . .200
1016.1 Discharge . . . . . . . . . . . . . . . . . . .200
1016.2 Authority Having Jurisdiction . . . .200
1016.3 Construction and Size . . . . . . . . .200
1016.4 Separate Use . . . . . . . . . . . . . . . .200
1017.0 Oil and Flammable Liquid Interceptors . . . . . . . . . . . . . . . . . .200
1017.1 Interceptors Required . . . . . . . . . .200
1017.2 Interceptor Design Alternatives . . .200
1017.3 Interceptor Details . . . . . . . . . . . .200
1017.4 Design of Interceptors . . . . . . . . .200
CHAPTER 11 STORM DRAINAGE . . . . . . . . . .203
1101.0 General . . . . . . . . . . . . . . . . . . . . .205
CPC § 1014.3.7 High relevance — show source text
1014.3.7 Abandoned Gravity Grease Intercep- tors. Abandoned grease interceptors shall be pumped and filled as required for abandoned sewers and sewage disposal facilities in Section 722.0.
DRAINAGE FIXTURE UNITS1, 3
(DFUs)INTERCEPTOR VOLUME2
(gallons)
8500
21750
351000
901250 172 1500
2162000
3072500
3423000
4284000
5765000
7207500 2112 10 000
264015 000 For SI units: 1 gallon = 3.785 L
Notes: 1 The maximum allowable DFUs plumbed to the kitchen drain lines that will be connected to the grease interceptor. 2 This size is based on DFUs, the pipe size from this code; Table 703.2; Useful Tables for flow in half-full pipes (ref: Mohinder Nayyar Piping Handbook, 3rd Edition, 1992). Based on 30-minute retention time (ref.: George Tchobanoglous and Metcalf & Eddy. Wastewater Engineering Treatment, Disposal, and Reuse, 3rd Ed. 1991 & Ronald Crites and George Tchobanoglous. Small and Decentralized Wastewater Management Systems, 1998). Rounded up to nominal interceptor volume. 3 Where the flow rate of directly connected fixture(s) or appliance(s) have no assigned DFU values, the additional grease interceptor volume shall be based on the known flow rate (gpm) (L/s) multiplied by 30 minutes.
EXAMPLE 1014.3.6
GRAVITY GREASE INTERCEPTOR SIZING EXAMPLE
Given: A restaurant with the following fixtures and equip ment.
One food preparation sink; three-floor drains - one in the food prep area, one in the grill area, and one receiving the indirect waste from the ice machine and a mop sink.
Kitchen Drain Line DFU Count (from Table 702.1):
3 floor drains at 2 DFUs each = 6 DFUs
Mop sink at 3 DFUs each = 3 DFUs
Food prep sink at 3 DFUs each = 3 DFUs
Total = 12 DFUs
Using Table 1014.3.6, the grease interceptor will be sized at 750 gallons (2389 L).
1015.0 FOG (Fats, Oils, and Greases) Disposal Sys- tem.
1015.1 Purpose. The purpose of this section is to provide the necessary criteria for the sizing, application, and installation of FOG disposal systems designated as a pretreatment or discharge water quality compliance strategy.
TABLE 1014.3.6
GRAVITY GREASE INTERCEPTOR SIZING
2025 CALIFORNIA PLUMBING CODE 199
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TRAPS AND INTERCEPTORS
CPC § 0.06 High relevance — show source text
For SI units: 1 inch = 25 mm, 1 gallon per minute = 0.06 L/s
Notes: 1 For interceptor sizing by the fixture capacity see the example below. 2 1 ∕ 4 inch slope per foot (20.8 mm/m) based on Manning’s formula with friction factor N = 0.012.
EXAMPLE 1014.2.1
SIZING HYDROMECHANICAL GREASE INTERCEPTOR(S)
USING FIXTURE CAPACITY
Step 1: Determine the flow rate from each fixture.
[Length] X [Width] X [Depth] / [231] = Gallons X [0.75 fill factor] / [Drain
Period (1 minute or 2 minutes)]
Step 2: Calculate the total load from fixtures that discharge into
the interceptor.
FIXTURES COMPART-
MENTSLOAD
(gallons)SIZE OF
GREASE
INTERCEPTOR
ONE-MINUTE
DRAINAGE
PERIOD
(gpm)TWO-
MINUTE
DRAINAGE
PERIOD
(gpm)
Compartment
size–– –– –– ––
24 inches x 24
inches x 12
inches2 44.9 –– ––
Hydrant–– 3 –– ––
Rated
Appliance–– 2 –– ––
–––– 49.9 50 25 For SI units: 1 inch = 25.4 mm, 1 gallon per minute = 0.06 L/s, 1 gallon =
3.785 L
1014.3 Gravity Grease Interceptors. Required gravity grease interceptors shall comply with the provisions of Section 1014.3.1 through Section 1014.3.7.
1014.3.1 General. The provisions of this section shall apply to the design, construction, installation, and testing of commercial kitchen gravity grease interceptors.
1014.3.2 Waste Discharge Requirements. Waste discharge in establishments from fixtures and equipment
For SI units: 1 inch = 25.4 mm, 1 gallon per minute = 0.06 L/s, 1 gallon =
3.785 L
198 2025 CALIFORNIA PLUMBING CODE
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TRAPS AND INTERCEPTORS
which contain grease, including but not limited to, scullery sinks, pot and pan sinks, dishwashers, soup kettles, and floor drains located in areas where grease-containing materials exist, shall be permitted to be drained into the sanitary waste through the interceptor where approved by the Authority Having Jurisdiction.
1014.3.2.1 Toilets and Urinals. Toilets, urinals, and other similar fixtures shall not drain through the interceptor.
1014.3.2.2 Inlet Pipe. Waste shall enter the interceptor through the inlet pipe.
1014.3.3 Design. Gravity interceptors shall be constructed in accordance with the applicable standard in Chapter 17 or the design approved by the Authority Having Jurisdiction.
CPC § 1009.1 High relevance — show source text
1009.1 Where Required . . . . . . . . . . . . . .196
Table 1009.1 Approved Interceptors (Clarifiers) . .196
1009.2 Approval . . . . . . . . . . . . . . . . . . . .196
1009.3 Design . . . . . . . . . . . . . . . . . . . . .196
2025 CALIFORNIA PLUMBING CODE xxxvii
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TABLE OF CONTENTS
1009.4 Relief Vent . . . . . . . . . . . . . . . . . .196
1009.5 Location . . . . . . . . . . . . . . . . . . . .196
1009.6 Maintenance of Interceptors . . . . .196
1009.7 Discharge . . . . . . . . . . . . . . . . . . .196
1010.0 Slaughterhouses, Packing Establishments, etc . . . . . . . . . . .196
1010.1 General . . . . . . . . . . . . . . . . . . . . .196
1010.2 Meat and Poultry Processing Plants . . . . . . . . . . . . . . . . . . . . . .197
1010.3 Collection Centers and
Facilities . . . . . . . . . . . . . . . . . . . .197
1010.4 Horse Meat and Pet Food
Establishments . . . . . . . . . . . . . . .197
1010.5 Draining and Plumbing . . . . . . . .197
1011.0 Minimum Requirements for Auto Wash Racks . . . . . . . . . . . . .197
1011.1 General . . . . . . . . . . . . . . . . . . . . .197
1012.0 Commercial and Industrial
Laundries . . . . . . . . . . . . . . . . . . .197
1012.1 General . . . . . . . . . . . . . . . . . . . . .197
1013.0 Bottling Establishments . . . . . . . .197
1013.1 General . . . . . . . . . . . . . . . . . . . . .197
1014.0 Grease Interceptors . . . . . . . . . . .197
1014.1 General . . . . . . . . . . . . . . . . . . . . .197
1014.2 Hydromechanical Grease Interceptors . . . . . . . . . . . . . . . . . .198
Table 1014.2.1 Hydromechanical Grease Interceptor Sizing Using Gravity Flow Rates . . . . . . . . . . . .198
1014.3 Gravity Grease Interceptors . . . . .198
Table 1014.3.6 Gravity Grease Interceptor Sizing . . . . . . . . . . . . . . . . . . . . . .199
CPC § 1009.1 High relevance — show source text
TABLE 1009.1 APPROVED INTERCEPTORS (CLARIFIERS)
APPLICATION STANDARD
Fats, Oil, Grease
(FOG)ASME A112.14.3, ASME A112.14.4,
ASME A112.14.6, CSA B481,
ANSI/CAN/IAPMO Z1001,
PDI G-101, PDI G-102Solid Waste IAPMO IGC 167
Non-petroleum OilASME A112.14.6, IAPMO PS 80,
PDI G-102
Petroleum OilASTM D6104, IAPMO IGC 183,
IAPMO IGC 3251009.2 Approval. The size, type, and location of each interceptor (clarifier) or separator shall be approved by the Authority Having Jurisdiction. Except where otherwise specifically permitted, no wastes other than those requiring treatment or separation shall be discharged into an interceptor (clarifier). 1009.3 Design. Interceptors (clarifiers) for sand and similar heavy solids shall be so designed and located as to be readily accessible for cleaning and shall have a water seal of not less than 6 inches (152 mm). 1009.4 Relief Vent. Interceptors (clarifiers) shall be so designed that they will not become air-bound where closed covers are used. Each interceptor (clarifier) shall be properly vented.
1009.5 Location. Each interceptor (clarifier) cover shall be readily accessible for servicing and maintaining the interceptor (clarifier) in working and operating condition. The use of ladders or the removal of bulky equipment to service interceptors (clarifiers) shall constitute a violation of accessibility. Location of interceptors (clarifiers) shall be shown on the approved building plan. 1009.6 Maintenance of Interceptors. Interceptors shall be maintained in efficient operating condition by periodic removal of accumulated grease, scum, oil, or other floating substances and solids deposited in the interceptor. 1009.7 Discharge. The waste pipe from oil and sand interceptors shall discharge as approved by the Authority Having Jurisdiction.
1010.0 Slaughterhouses, Packing Establishments, etc.
1010.1 General. A fish, fowl, and animal slaughterhouse or establishment; a fish, fowl, and meat packing or curing establishment; a soap factory, tallow-rendering, fat-rendering, and a hide-curing establishment shall be connected to and shall drain or discharge into an approved grease interceptor (clarifier).
TABLE 1009.1 APPROVED INTERCEPTORS (CLARIFIERS)
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TRAPS AND INTERCEPTORS
1010.2 Meat and Poultry Processing Plants. [AGR]
1010.2.1 Drainage and Plumbing Systems. Drainage and plumbing systems shall meet the require- ments of Section 724.0.
1010.2.1.1 Each floor drain shall be equipped with a deep-seal trap.
CPC § 1014.3.4 High relevance — show source text
1014.3.4 Location. Each grease interceptor shall be so installed and connected that it shall be easily accessible for inspection, cleaning, and removal of the intercepted grease. A gravity grease interceptor that complies with ANSI/CAN/IAPMO Z1001 shall not be installed in a
building where food is handled. Location of the grease interceptor shall meet the approval of the Authority Having Jurisdiction.
1014.3.4.1 Interceptors. Interceptors shall be placed as close as practical to the fixtures they serve.
1014.3.4.2 Business Establishment. Each
business establishment for which a gravity grease interceptor is required shall have an interceptor which shall serve that establishment unless other wise approved by the Authority Having Jurisdiction.
1014.3.4.3 Access. Each gravity grease interceptor shall be located to be readily accessible to the equipment required for maintenance.
1014.3.5 Construction Requirements. Gravity grease interceptors shall be designed to remove grease from effluent and shall be sized in accordance with this
section. Gravity grease interceptors shall also be designed to retain grease until accumulations can be removed by pumping the interceptor. When provided, a sample box shall be located at the outlet end of gravity grease interceptors so that the Authority Having Jurisdiction can periodically sample effluent quality.
1014.3.6 Sizing Criteria. The volume of the interceptor shall be determined by using Table 1014.3.6. Where drainage fixture units (DFUs) are not known, the interceptor shall be sized based on the maximum DFUs allowed for the pipe size connected to the inlet of the interceptor. Refer to Table 703.2, Drainage Piping, Horizontal.
1014.3.7 Abandoned Gravity Grease Intercep- tors. Abandoned grease interceptors shall be pumped and filled as required for abandoned sewers and sewage disposal facilities in Section 722.0.
DRAINAGE FIXTURE UNITS1, 3
(DFUs)INTERCEPTOR VOLUME2
(gallons)
8500
21750
351000
901250 172 1500
2162000
3072500
3423000
4284000
5765000
7207500 2112 10 000
264015 000 For SI units: 1 gallon = 3.785 L
Notes: 1 The maximum allowable DFUs plumbed to the kitchen drain lines that will be connected to the grease interceptor. 2 This size is based on DFUs, the pipe size from this code; Table 703.2; Useful Tables for flow in half-full pipes (ref: Mohinder Nayyar Piping Handbook, 3rd Edition, 1992). Based on 30-minute retention time (ref.: George Tchobanoglous and Metcalf & Eddy. Wastewater Engineering Treatment, Disposal, and Reuse, 3rd Ed. 1991 & Ronald Crites and George Tchobanoglous. Small and Decentralized Wastewater Management Systems, 1998). Rounded up to nominal interceptor volume.
CPC § 1010.5.2 High relevance — show source text
1010.5.2 Sewage and Plant Waste. The sewer sys- tem have adequate slope and capacity to remove readily all waste from the various processing operations and to minimize, or if possible, prevent stoppage and surcharg- ing of the system. When the sewage disposal system is a private system which is required to be approved by a state or local health authority, the applicant shall fur- nish the administrator a letter from the proper health authority indicating that the sewage disposal system is acceptable to such authority.
1011.0 Minimum Requirements for Auto Wash Racks.
1011.1 General. A private or public wash rack or floor or slab used for cleaning machinery or machine parts shall be adequately protected against storm or surface water and shall drain or discharge into an approved interceptor (clarifier).
1012.0 Commercial and Industrial Laundries.
1012.1 General. Laundry equipment in commercial and industrial buildings that do not have integral strainers shall discharge into an interceptor having a wire basket or similar device that is removable for cleaning and that will prevent passage into the drainage system of solids [1] ⁄ 2 of an inch (12.7 mm) or larger in maximum dimensions, such as string, rags, buttons, or other solid materials detrimental to the public sewerage system.
1013.0 Bottling Establishments.
1013.1 General. Bottling plants shall discharge their process wastes into an interceptor that will provide for the separation of broken glass or other solids, before discharging liquid wastes into the drainage system.
1014.0 Grease Interceptors.
1014.1 General. Where it is determined by the Authority Having Jurisdiction that waste pretreatment is required, an approved type of grease interceptor(s) shall comply with ASME A112.14.3, ASME A112.14.4, CSA B481, ANSI/CAN/IAPMO Z1001, PDI G-101, or PDI G-102, and sized in accordance with Section 1014.2.1 or Section
1014.3.6, shall be installed in accordance with the manufacturer’s installation instructions to receive the drainage from fixtures or equipment that produce grease-laden waste. Grease-laden waste fixtures shall include, but not be limited to, sinks and drains, such as floor drains, floor sinks, and other fixtures or equipment in serving establishments, such as restaurants, cafes, lunch counters, cafeterias, bars and clubs, hotels, hospitals, sanitariums, factory or school kitchens, or other establishments where grease is introduced into the drainage or sewage system in quantities that can effect line stoppage or hinder sewage treatment or private sewage disposal systems. A combination of hydromechanical, gravity grease interceptors and engineered systems shall be allowed to meet this code and other applicable requirements of the Authority Having Jurisdiction where space or existing physical constraints of existing buildings necessitate such installations. A grease interceptor shall not be required for individual dwelling units or private living quarters. Water closets, urinals, and other plumbing fixtures conveying human waste shall not drain into or through the grease interceptor.
1014.1A [OSHPD 1, 1R, 2, 3, 4 & 5] The Authority Having Jurisdiction is the individual official, board, department or agency authorized to administer and enforce the sewage treatment system in the area of the location of the health facil- ity.
CPC § 3.3.68.4 Medium relevance — show source text
Minimal Sedation (Anxiolysis). A drug-induced state during which patients respond normally to verbal commands. Although cognitive function and coordination may be impaired, ventilatory and cardiovascular functions are unaffected. [NFPA 99:3.3.68.4]
Moderate Sedation/Analgesia (Conscious Seda- tion). A drug-induced depression of consciousness during which patients respond purposefully to verbal commands, either alone or accompanied by light tactile stimulation. No interventions are required to maintain a patient airway, and spontaneous ventilation is adequate. Cardiovascular function is usually maintained. [NFPA 99:3.3.68.3]
Grade. The slope or fall of a line of pipe in reference to a horizontal plane. In drainage, it is usually expressed as the fall in a fraction of an inch (mm) or percentage slope per foot (meter) length of pipe.
Gravity Grease Interceptor. A plumbing appurtenance or appliance that is installed in a sanitary drainage system to intercept nonpetroleum fats, oils, and greases (FOG) from a wastewater discharge and is identified by volume, 30 minute retention time, baffle(s), not less than two compartments, a total volume of not less than 300 gallons (1135 L), and gravity separation. [These interceptors comply with the requirements of Chapter 10 or are designed by a registered design professional.] Gravity grease interceptors are generally installed outside.
Graywater. [BSC-CG & HCD 1] Pursuant to Health and Safety Code Section 17922.12, “graywater” means untreated wastewater that has not been contaminated by any toilet dis- charge, has not been affected by infectious, contaminated, or unhealthy bodily wastes, and does not present a threat from contamination by unhealthful processing, manufacturing, or operating wastes. "Graywater" includes, but is not limited to, wastewater from bathtubs, showers, bathroom washbasins, clothes washing machines, and laundry tubs, but does not include wastewater from kitchen sinks or dishwashers.
Note: For the purpose of applying the standards contained in this code, “Graywater” as defined above, has the same meaning as “gray water”, “grey water”, and “greywater”.
Gray Water System. [BSC-CG & HCD 1] A system designed to collect gray water on-site for reuse or distribution to an irrigation or disposal field. A gray water system may include, on-site treated nonpotable water devices or equip- ment, tanks, valves, filters, pumps or other appurtenances along with piping and receiving landscape.
Grease Interceptor. A plumbing appurtenance or appliance that is installed in a sanitary drainage system to intercept nonpetroleum fats, oil, and greases (FOG) from a wastewater discharge.
Grease Removal Device (GRD). A hydromechanical grease interceptor that automatically, mechanically removes non-petroleum fats, oils and grease (FOG) from the interceptor, the control of which are either automatic or manually initiated.
Grounding Electrode. A conducting object through which a direct connection to earth is established. [NFPA 70:100 (Part I)]
Groundwater. Water that exists beneath the earth’s surface.
CPC § 1014.2.1 Medium relevance — show source text
designed and installed so that the total flow through such device or devices shall at no time be greater than the rated flow of the connected grease interceptor. No flow control device having adjustable or removable parts shall be approved. The vented flow control device shall be located such that no system vent shall be between the flow control and the grease interceptor inlet. The vent or air inlet of the flow control device shall connect with the sanitary drainage vent system, as elsewhere required by this code, or shall terminate through the roof of the building, and shall not terminate to the free atmosphere inside the building.
Exception: Listed grease interceptors with integral flow controls or restricting devices shall be installed in an accessible location in accordance with the manufacturer’s installation
instructions.
1014.2.1 Capacity. The total capacity in gallons (gal) (L) of fixtures discharging into a hydromechanical grease interceptor shall not exceed two and one-half times the certified gallon per minute (gpm) (L/s) flow rate of the interceptor in accordance with Table 1014.2.1.
For this section, the term “fixture” shall mean and include each plumbing fixture, appliance, apparatus, or other equipment required to be connected to or discharged into a grease interceptor by a provision of this section.
1014.2.2 Vent. A vent shall be installed downstream of
hydromechanical grease interceptors in accordance with the requirements of this code.
TABLE 1014.2.1
HYDROMECHANICAL GREASE INTERCEPTOR SIZING USING GRAVITY FLOW RATES [1]
DIAMETER OF
GREASE WASTE
PIPE (inches)MAXIMUM FULL
PIPE FLOW
(gpm)2SIZE OF GREASE INTERCEPTOR Col4
DIAMETER OF
GREASE WASTE
PIPE (inches)MAXIMUM FULL
PIPE FLOW
(gpm)2ONE-MINUTE
DRAINAGE
PERIOD
(gpm)TWO-MINUTE
DRAINAGE
PERIOD
(gpm)
220 20 10
360 75 35
4125 150 75
5230 250 125
6375 400 200 For SI units: 1 inch = 25 mm, 1 gallon per minute = 0.06 L/s
Notes: 1 For interceptor sizing by the fixture capacity see the example below. 2 1 ∕ 4 inch slope per foot (20.8 mm/m) based on Manning’s formula with friction factor N = 0.012.
EXAMPLE 1014.2.1
SIZING HYDROMECHANICAL GREASE INTERCEPTOR(S)
USING FIXTURE CAPACITY
Step 1: Determine the flow rate from each fixture.
[Length] X [Width] X [Depth] / [231] = Gallons X [0.75 fill factor] / [Drain
Period (1 minute or 2 minutes)]
Step 2: Calculate the total load from fixtures that discharge into
the interceptor.
CPC § 3.785 Medium relevance — show source text
3.785 L
1014.3 Gravity Grease Interceptors. Required gravity grease interceptors shall comply with the provisions of Section 1014.3.1 through Section 1014.3.7.
1014.3.1 General. The provisions of this section shall apply to the design, construction, installation, and testing of commercial kitchen gravity grease interceptors.
1014.3.2 Waste Discharge Requirements. Waste discharge in establishments from fixtures and equipment
For SI units: 1 inch = 25.4 mm, 1 gallon per minute = 0.06 L/s, 1 gallon =
3.785 L
198 2025 CALIFORNIA PLUMBING CODE
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
TRAPS AND INTERCEPTORS
which contain grease, including but not limited to, scullery sinks, pot and pan sinks, dishwashers, soup kettles, and floor drains located in areas where grease-containing materials exist, shall be permitted to be drained into the sanitary waste through the interceptor where approved by the Authority Having Jurisdiction.
1014.3.2.1 Toilets and Urinals. Toilets, urinals, and other similar fixtures shall not drain through the interceptor.
1014.3.2.2 Inlet Pipe. Waste shall enter the interceptor through the inlet pipe.
1014.3.3 Design. Gravity interceptors shall be constructed in accordance with the applicable standard in Chapter 17 or the design approved by the Authority Having Jurisdiction.
1014.3.4 Location. Each grease interceptor shall be so installed and connected that it shall be easily accessible for inspection, cleaning, and removal of the intercepted grease. A gravity grease interceptor that complies with ANSI/CAN/IAPMO Z1001 shall not be installed in a
building where food is handled. Location of the grease interceptor shall meet the approval of the Authority Having Jurisdiction.
1014.3.4.1 Interceptors. Interceptors shall be placed as close as practical to the fixtures they serve.
1014.3.4.2 Business Establishment. Each
business establishment for which a gravity grease interceptor is required shall have an interceptor which shall serve that establishment unless other wise approved by the Authority Having Jurisdiction.
1014.3.4.3 Access. Each gravity grease interceptor shall be located to be readily accessible to the equipment required for maintenance.
1014.3.5 Construction Requirements. Gravity grease interceptors shall be designed to remove grease from effluent and shall be sized in accordance with this
section. Gravity grease interceptors shall also be designed to retain grease until accumulations can be removed by pumping the interceptor. When provided, a sample box shall be located at the outlet end of gravity grease interceptors so that the Authority Having Jurisdiction can periodically sample effluent quality.
1014.3.6 Sizing Criteria. The volume of the interceptor shall be determined by using Table 1014.3.6. Where drainage fixture units (DFUs) are not known, the interceptor shall be sized based on the maximum DFUs allowed for the pipe size connected to the inlet of the interceptor. Refer to Table 703.2, Drainage Piping, Horizontal.
CPC § 910.0 Medium relevance — show source text
Combination waste
and vent piping . . . . . . . . . . . . . . . . .910.0, Appendix B Combustion air openings . . . . . . . . . . . . .506.3 – 506.5 Condensate pipe . . . . . . . . . . . . . . . .814.3, Table 814.3 Disposal fields . . . . . . . . . . . . . . . . . . . . . . .Appendix H Drainage piping . . . . . . . . . . . . . . . .Table 702.1, 703.0, Table 703.2, C 304.0,
E 302.2, E 504.4
FOG disposal systems . . . . . . . . . . . . . . . . . . . . .1015.3
Fuel gas piping systems . . . . . .1208.3, 1214.0, 1215.0,
E 403.2, Table E 403.2
Fuel gas vents . . . . . . . . . . . . . . . . . . .509.6.2, 509.7.4,
509.10.2, 510.0
Flushometer valves and tanks . . . . . . . . .610.10, 610.11
Gray water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1503.8
Grease interceptors . . . . . . . . .1014.2.1, Table 1014.2.1,
1014.3.6, Table 1014.3.6
Hanger rods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .313.6
Indirect waste pipes . . . . . . . . . . . . . . . . .801.3.1, 803.3
Leaders, conductors,
and storm drains . . . . . . . . . . .1103.0, Table 1103.1,
Table 1103.2, Table 1103.3
Louvers, grilles, and screens . . . . . . . . . . . . . . . . .506.8
Medical gas and medical vacuum pipe . . . . . . .1323.1.1
Mulch basins . . . . . . . . . . . . . . . . . . . . . . . . . .1504.5.1
Oil tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .E 403.12
Pipe cleanouts . . . . . . . . . . . . . . . . .Table 707.1, 707.10
Rainwater catchment systems . . . . . . . .1602.6, K 106.5
Reclaimed (recycled)
water piping . . . . . . . . . . . . . . . . . . . . . . . . . . .1502.6
Roof drainage . . . . . . . . . . . . . . . .1101.12, Table 1103.2,
Table 1103.3, 1105.1,
1603.15, Appendix D, K 106.4
Frequently asked questions
How are hydromechanical grease interceptors sized under the CPC?
Hydromechanical interceptors are sized using the interceptor’s certified gpm and the connected fixture capacity; see §1014.2.1 and Table 1014.2.1 for the flow/pipe‑diameter and one‑ or two‑minute drainage period sizing method .
When must a gravity grease interceptor be used and how is its volume determined?
When the Authority Having Jurisdiction requires a gravity interceptor, design and installation follow §1014.3.1–§1014.3.7; interceptor volume is determined by Table 1014.3.6 (DFU-based sizing, 30‑minute retention) or by maximum DFUs for the inlet pipe size .
Can dishwashers or food waste disposers discharge into grease interceptors?
The CPC generally prohibits food waste disposers and dishwashers from discharging into grease interceptors, except where an interceptor is specifically designed to receive such discharge; see §1014.1.3 for the restriction and its exception .
More in California Plumbing Code
- Administration
- Definitions
- General Regulations
- Plumbing Fixtures and Fixture Fittings
- Water Heaters
- Water Supply and Distribution
- Sanitary Drainage (Drain, Waste, and Vent)
- Indirect Wastes
- Vents
- Traps and Interceptors
- Storm Drainage
- Fuel Gas Piping
- Health Care Facilities — Medical Gas and Medical Vacuum Systems
- Alternate Water Sources and Nonpotable Rainwater Catchment Systems
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