CPC · California Plumbing Code
Oil and flammable liquid interceptor requirements, vents, and overflow
If your garage, gas station, or factory produces oily or flammable liquid waste, the California Plumbing Code requires an oil/flammable‑liquid interceptor. It must be vented separately to outdoors, use minimum vent and pipe diameters (2" flammable vapor vent, 3" waste line), provide gastight cleanouts, and route any overflow to an approved 550‑gal waste oil tank; manufactured units must be stamped with their full discharge rate (see §§ 1017.1, 1017.3, 1017.4) .
Last reviewed: July 6, 2026
What the code requires — 2-4 sentences
Repair garages, gasoline stations with grease racks/pits, and factories that produce oily or flammable wastes must be provided with an oil or flammable liquid interceptor; floor drains in those locations must connect directly to the interceptor (§ 1017.1) . Interceptors must meet venting, waste‑line, overflow, and rating/size rules in § 1017.3 and § 1017.4 (vents, minimum vent and pipe diameters, overflow routing to an approved waste‑oil tank, manufacturer rating or minimum dimensional requirements) .
The single most important rule: if your site produces oily or flammable liquid waste (repair garage, gas station, factory), you must use an oil/flammable‑liquid interceptor sized, vented, and piped as required by § 1017.1, § 1017.3, and § 1017.4 .
Requirements in detail
Where an interceptor is required
- Who: Repair garages, gasoline stations with grease racks/pits, and factories with oily or flammable wastes. Floor drains in these locations must discharge directly to an oil/flammable liquid interceptor (§ 1017.1) .
Venting (separation/vapor compartments and vapor vents)
- Each separation or vapor compartment must be independently vented to the outer air; if multiple separation/vapor compartments are used they may either each have their own vent or connect to a header that is installed at least 6 inches above the spill line of the lowest floor drain and then vented independently to the outer air (§ 1017.3(1)) .
- Minimum flammable vapor vent size: 2 inches. If the flammable vapor vent discharges through a sidewall it must terminate at least 10 feet above the adjacent level at an approved location (§ 1017.3(2)) .
- The interceptor must be vented on the sewer side and must not connect to a flammable vapor vent (separate systems). Interceptors must have gastight cleanout covers that are readily accessible (§ 1017.3(3)) .
Waste line, cleanouts
- The waste (discharge) line from the interceptor must be at least 3 inches in diameter and must include a full‑size cleanout to grade (§ 1017.3(4)) .
Overflow — routing and receiving tank
- If an interceptor is provided with an overflow, the overflow must be piped with at least a 2‑inch line to an approved waste oil tank with a minimum capacity of 550 gallons, and the tank must meet Authority Having Jurisdiction (AHJ) requirements (§ 1017.3(5)) .
- The separator’s waste oil may flow by gravity or be pumped to higher elevation by an automatic pump; pumps must be adequately sized and accessible (§ 1017.3(5)(a)–(b)) .
- The waste oil tank must have a 2‑inch minimum pump‑out connection at grade and a 1 1/2‑inch minimum vent to atmosphere terminating at an approved location not less than 10 feet above grade (§ 1017.3(5)(c)) .
Rating, capacity, and dimensional minimums
- Manufactured (rated) interceptors must be stamped/labeled with their full discharge rate (gpm) by the manufacturer. The interceptor must be rated equal to or greater than the incoming flow and must have an overflow line to an underground tank (§ 1017.4(1)) .
- For interceptors not rated by the manufacturer:
- Minimum depth: 2 feet below the invert of the discharge drain.
- Minimum water seal at the outlet opening: 18 inches.
- Minimum capacities (where motor vehicles are involved): 6 cubic feet minimum where not more than three vehicles are serviced/stored; add 1 cubic foot per vehicle for each vehicle up to 10 vehicles. Above 10 vehicles the AHJ determines size. Where vehicles are serviced but not stored, capacity may be based on 1 cubic foot per 100 sq ft drained into the interceptor with a minimum of 6 cubic feet (§ 1017.4(2) and (2)(a–c)) .
Quick decision table
| Decision element | Required value / threshold | Code Reference |
|---|---|---|
| Locations required to have interceptors | Repair garages, gasoline stations with grease racks/pits, factories with oily/flammable wastes | § 1017.1 |
| Separation/vapor compartment venting | Independently vented to outer air; header allowed with header installed ≥ 6 in above lowest spill line | § 1017.3(1) |
| Minimum flammable vapor vent size | 2 in | § 1017.3(2) |
| Sidewall vapor vent termination height | 10 ft above adjacent level | § 1017.3(2) |
| Waste (discharge) pipe size | 3 in minimum | § 1017.3(4) |
| Overflow line size | 2 in minimum | § 1017.3(5) |
| Minimum waste oil tank capacity (overflow destination) | 550 gallons | § 1017.3(5) |
| Manufactured interceptor labeling | Must be stamped/labeled with full discharge rate | § 1017.4(1) |
| Minimum depth (non‑rated interceptor) | 2 ft below invert of discharge drain | § 1017.4(2) |
| Minimum outlet water seal (non‑rated) | 18 in | § 1017.4(2) |
| Minimum interceptor capacity (≤3 vehicles) | 6 cu ft (add 1 cu ft per vehicle up to 10) | § 1017.4(2)(a) |
| Waste oil tank pump‑out connection | 2 in minimum pump‑out at grade | § 1017.3(5)(c) |
| Waste oil tank vent to atmosphere | 1 1/2 in min; discharge ≥10 ft above grade | § 1017.3(5)(c) |
Exceptions & special cases
- The code allows use of prefabricated, tested, and listed oil interceptors that comply with an accepted standard (see § 1017.2 referencing IAPMO IGC 183). If you use a rated, labeled product, sizing is based on the manufacturer's full discharge rate and must equal or exceed incoming flow (§ 1017.2, § 1017.4(1)) .
- Where multiple vapor compartments are present, connecting to a header is permitted only if the header is installed at least 6 inches above the lowest floor drain spill line and each compartment is still vented to the outer air (header must be independently vented) (§ 1017.3(1)) .
- Above‑10‑vehicle facilities: interceptor capacity is determined by the Authority Having Jurisdiction (AHJ), not by the fixed table values in § 1017.4(2)(b) .
Common mistakes
- Connecting the interceptor’s sewer‑side vent to the flammable vapor vent (prohibited). The sewer vent and the flammable vapor vent must remain separate (§ 1017.3(3)) .
- Undersizing vents or vent terminations: using less than 2‑inch vents for flammable vapors, or terminating a sidewall vent less than 10 feet above adjacent level, violates § 1017.3(2) .
- Using an interceptor without a manufacturer rating but failing to meet the 2‑ft depth and 18‑inch water‑seal minimums required for non‑rated units (§ 1017.4(2)) .
- Failing to provide an overflow line (≥ 2 in) to a 550‑gal approved tank when an overflow is present (§ 1017.3(5)) .
- Omitting gastight cleanout covers or not making them readily accessible (§ 1017.3(3)) .
Worked example — gas station with 8 service stalls
Scenario: A small gasoline service facility with 8 vehicle service stalls and floor drains that will discharge oily wastes.
- Interceptor capacity (non‑rated method): base 6 cu ft for up to 3 vehicles, then +1 cu ft per vehicle for each additional vehicle up to 10 vehicles. For 8 vehicles: 6 + (8 − 3) × 1 = 11 cubic feet minimum interceptor capacity (§ 1017.4(2)(a)) .
- Depth & water seal (if using an un‑rated unit): provide ≥ 2 ft depth below invert and an ≥ 18‑inch water seal at the outlet (§ 1017.4(2)) .
- Venting: each separation/vapor compartment must be independently vented to outer air; use ≥ 2‑inch flammable vapor vent(s). If any vent exits a sidewall, terminate at least 10 ft above adjacent level (§ 1017.3(1)–(2)) .
- Waste pipe & cleanouts: the interceptor discharge must be at least 3 inches with a full‑size cleanout to grade (§ 1017.3(4)) .
- Overflow provision: if the interceptor has an overflow, pipe the overflow ≥ 2 inches to an approved waste oil tank ≥ 550 gallons; provide a 2‑inch pump‑out at grade and a 1½‑inch vent to atmosphere located ≥ 10 ft above grade; pumps (if used) must be automatic, accessible, and sized as required (§ 1017.3(5)(a–c)) .
- Alternatively, choose a manufactured, rated interceptor that is stamped with its full discharge rate and sized so the rated discharge ≥ incoming flow; if using a rated unit follow the manufacturer rating and still provide required vents/overflow routing (§ 1017.4(1)) .
Related provisions
- § 1017.2 — Interceptor design alternatives; reference to IAPMO IGC 183 for oil/water separators
- § 1009.1 — Where interceptors/clarifiers are required generally and acceptable standards (Table 1009.1)
- § 1009.4 — Relief venting requirement for interceptors (prevent air‑bound condition)
- § 1016.4 — Venting requirement for sand and similar interceptors (related venting discussion)
Code references
Grounded in the retrieved California Plumbing Code — click a citation to read the verbatim passage:
CPC § 0.2 High relevance — show source text
These openings shall be staggered so that there cannot be a straight line flow between the inlet pipe and the outlet pipe. The invert of the inlet pipe shall be no lower than the invert of the outlet pipe.
The sand interceptor shall have a minimum dimension of 2 square feet (0.2 m [2] ) for the net free opening of the inlet section and a minimum depth under the invert of the outlet pipe of 2 feet (610 mm).
For each 5 gpm (0.3 L/s) flow or fraction thereof over 20 gpm (1.26 L/s), the area of the sand interceptor inlet section is to be increased by 1 square foot (0.09 m [2] ). The outlet section shall at all times have a minimum area of 50 percent of the inlet section.
The outlet section shall be covered by a solid removable cover, set flush with the finished floor, and the inlet section shall have an open grating, set flush with the finished floor and suitable for the traffic in the area in which it is located.
1016.4 Separate Use. Sand and similar interceptors for every solid shall be so designed and located as to be readily accessible for cleaning, shall have a water seal of not less than 6 inches (152 mm), and shall be vented.
1017.0 Oil and Flammable Liquid Interceptors.
1017.1 Interceptors Required. Repair garages and gasoline stations with grease racks or grease pits, and factories that have oily, flammable, or both types of wastes as a result of manufacturing, storage, maintenance, repair, or testing processes, shall be provided with an oil or flammable liquid interceptor. Floor drains in such locations shall be connected directly to oil and flammable liquid interceptors.
1017.2 Interceptor Design Alternatives. Oil interceptors shall comply with IAPMO IGC 183 or be in accordance with Section 1017.3 through Section 1017.4.
1017.3 Interceptor Details. Oil and flammable liquid interceptors shall be in accordance with the following:
(1) The separation or vapor compartment shall be independently vented to the outer air. Where two or more separation or vapor compartments are used, each shall be vented to the outer air or shall be permitted to connect to a header that is installed at a minimum of 6 inches (152 mm) above the spill line of the lowest floor drain and vented independently to the outer air.
(2) The minimum size of a flammable vapor vent shall be not less than 2 inches (50 mm), and, where vented through a sidewall, the vent shall be not less than 10 feet (3048 mm) above the adjacent level at an approved location.
(3) The interceptor shall be vented on the sewer side and shall not connect to a flammable vapor vent. Oil and flammable interceptors shall be provided with gastight cleanout covers that shall be readily accessible.
(4) The waste line shall be not less than 3 inches (80 mm) in diameter with a full-size cleanout to grade.
(5) Where an interceptor is provided with an overflow, it shall be provided with an overflow line [not less than 2 inches (50 mm) in diameter] to an approved waste oil tank having a minimum capacity of 550 gallons (2082 L) and meeting the requirements of the Authority Having Jurisdiction.
(a) The waste oil from the separator shall flow by gravity or shall be pumped to a higher elevation by an automatic pump.
CPC § 1017.2 High relevance — show source text
1017.2 Interceptor Design Alternatives. Oil interceptors shall comply with IAPMO IGC 183 or be in accordance with Section 1017.3 through Section 1017.4.
1017.3 Interceptor Details. Oil and flammable liquid interceptors shall be in accordance with the following:
(1) The separation or vapor compartment shall be independently vented to the outer air. Where two or more separation or vapor compartments are used, each shall be vented to the outer air or shall be permitted to connect to a header that is installed at a minimum of 6 inches (152 mm) above the spill line of the lowest floor drain and vented independently to the outer air.
(2) The minimum size of a flammable vapor vent shall be not less than 2 inches (50 mm), and, where vented through a sidewall, the vent shall be not less than 10 feet (3048 mm) above the adjacent level at an approved location.
(3) The interceptor shall be vented on the sewer side and shall not connect to a flammable vapor vent. Oil and flammable interceptors shall be provided with gastight cleanout covers that shall be readily accessible.
(4) The waste line shall be not less than 3 inches (80 mm) in diameter with a full-size cleanout to grade.
(5) Where an interceptor is provided with an overflow, it shall be provided with an overflow line [not less than 2 inches (50 mm) in diameter] to an approved waste oil tank having a minimum capacity of 550 gallons (2082 L) and meeting the requirements of the Authority Having Jurisdiction.
(a) The waste oil from the separator shall flow by gravity or shall be pumped to a higher elevation by an automatic pump.
(b) Pumps shall be adequately sized and accessible.
(c) Waste oil tanks shall have a 2 inch (50 mm) minimum pump-out connection at grade and an 1 [1] ⁄ 2 inch (40 mm) minimum vent to atmosphere at an approved location not less than 10 feet (3048 mm) above grade. 1017.4 Design of Interceptors. Each manufactured interceptor that is rated shall be stamped or labeled by the manufacturer with an indication of its full discharge rate in gpm (L/s). The following shall apply:
(1) The full discharge rate to such an interceptor shall be determined at full flow. Each interceptor shall be rated equal to or greater than the incoming flow and shall be provided with an overflow line to an underground tank.
(2) Interceptors not rated by the manufacturer shall have a depth of not less than 2 feet (610 mm) below the invert of the discharge drain. The outlet opening shall have not
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200 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
less than an 18 inch (457 mm) water seal and shall have a minimum capacity as follows:
(a) Where not more than three motor vehicles are serviced, stored, or both, interceptors shall have a minimum capacity of 6 cubic feet (0.2 m [3] ), and 1 cubic foot (0.03 m [3] ) of capacity shall be added for each vehicle up to 10 vehicles.
(b) Above 10 vehicles, the Authority Having Jurisdiction shall determine the size of the interceptor required.
CPC § 1303.9 High relevance — show source text
Infection Control and Construction Risk
Assessment Professional Qualification Standard|Professional
Qualifications|1303.9| |IAPMO IGC 78-2019|Drain, Waste and Vent (DWV) Internal Cleanout Fittings|DWV Components|Table 707.2| |IAPMO IGC 109-2019|Water Distribution Manifolds|Valves|606.5.1| |IAPMO IGC 127-2018|Combined Hand-Washing Systems|Fixtures|407.1, 420.1| |IAPMO IGC 154-2019|Shower and Tub/Shower Enclosures, Bathtubs with Glass Pres-
sure-Sealed Doors, and Shower/Steam Panels|Fixtures|408.1| |IAPMO IGC 167-2011ae2
(R2021)|Solid Waste Containment Interceptors|Interceptors|Table 1009.1| |IAPMO IGC 183-2016|Oil/Water Separators and Coalescing Plate Separators|DWV Components|Table 1009.1, 1017.2| |IAPMO IGC 196-2018|Condensate Traps and Overflow Switches for Air-Conditioning
Systems|Condensate Traps|814.4| |IAPMO IGC 224-2018|ABS, PVC and Cast Iron DWV Test Fitting with Integral
Cleanout|DWV Components|Table 707.2| |IAPMO IGC 305-2019|ABS and PVC Horizontal Backwater Valves with Lifting
Devices|Valves|710.6| |IAPMO IGC 322-2018|Alkaline Water – Drinking Water Treatment Units|Miscellaneous|611.1.1| |IAPMO IGC 324-2019|Alternate Water Source Systems for Multi-Family, Residential,
and Commercial Use|Water Quality|1501.7, 1506.8,
1506.10.2, 1603.4| |IAPMO IGC 325-2016|Oil/Water Separators Performance|Interceptors|Table 1009.1| |IAPMO PS 53-2020|Grooved Mechanical Pipe Couplings and Grooved Fittings|Fittings|Table 604.1| |IAPMO PS 65-2019a|Airgap Units for Water Conditioning Equipment Installation|Backflow Protection|611.2| |IAPMO PS 66-2015|Dielectric Fittings|Fittings|605.15, 605.16.1,
605.16.3| |IAPMO PS 72-2019|Valves with Atmospheric Vacuum Breakers|Valves|603.5.6(5)| |IAPMO PS 76-2021|Trap Primers for Fill Valves and Flushometer Valves|DWV Components|1007.2| |IAPMO PS 80-2019|Clarifiers|Interceptors|Table 1009.1| |IAPMO PS 90-2014|Elastomeric Test Caps, Cleanout Caps, and Combination Test
Caps/Shielded Couplings|DWV Components|Table 707.2| |IAPMO PS 104-2019|Pressure Relief Connection for Dispensing Equipment|Valves|603.5.22(1)| |IAPMO PS 106-2015el|Tileable Shower Receptors and Shower Kits|Fixtures|408.2| |IAPMO PS 117-2021|Press Connections|Fittings|Table 604.1| |CSA B45.CPC § 1017.4 Medium relevance — show source text
(b) Pumps shall be adequately sized and accessible.
(c) Waste oil tanks shall have a 2 inch (50 mm) minimum pump-out connection at grade and an 1 [1] ⁄ 2 inch (40 mm) minimum vent to atmosphere at an approved location not less than 10 feet (3048 mm) above grade. 1017.4 Design of Interceptors. Each manufactured interceptor that is rated shall be stamped or labeled by the manufacturer with an indication of its full discharge rate in gpm (L/s). The following shall apply:
(1) The full discharge rate to such an interceptor shall be determined at full flow. Each interceptor shall be rated equal to or greater than the incoming flow and shall be provided with an overflow line to an underground tank.
(2) Interceptors not rated by the manufacturer shall have a depth of not less than 2 feet (610 mm) below the invert of the discharge drain. The outlet opening shall have not
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200 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
less than an 18 inch (457 mm) water seal and shall have a minimum capacity as follows:
(a) Where not more than three motor vehicles are serviced, stored, or both, interceptors shall have a minimum capacity of 6 cubic feet (0.2 m [3] ), and 1 cubic foot (0.03 m [3] ) of capacity shall be added for each vehicle up to 10 vehicles.
(b) Above 10 vehicles, the Authority Having Jurisdiction shall determine the size of the interceptor required.
(c) Where vehicles are serviced and not stored, interceptor capacity shall be based on a net capacity of 1 cubic foot (0.03 m [3] ) for each 100 square feet (9.29 m [2] ) of the surface to be drained into the interceptor, with a minimum of 6 cubic feet (0.2 m [3] ).
2025 CALIFORNIA PLUMBING CODE 201
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
202 2025 CALIFORNIA PLUMBING CODE
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
CALIFORNIA PLUMBING CODE – MATRIX ADOPTION TABLE
CHAPTER 11 - STORM DRAINAGE
(Matrix Adoption Tables are non-regulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)
CPC § 120.10 Medium relevance — show source text
4(f)2 Variable Air volume (VAV) 120.10(a), 140.4(c)2, 140.4(d), 140.9(c)4, 141.0(a)2, 141.0(b)3, 160.2(c)7, 170.2(c)4A, 170.2(c)4B, Table 170.2-B, Table 170.2-C, Table 180.2-D Capacity heat pump (VCHP) 150.1(b)3, 170.1(d)2 Exhaust 140.9(c)3 Flow control 140.4(k)6, 160.3(d), 170.2(c)4I Fluid flow 140.4(k)1, 170.2(c)4I Speed 120.6(a), 120.6(b)5 Speed compressor 120.6(a)3, 120.6(a)7, 150.0(m)13, 160.3(b)5L Speed control 140.4(k)6, 140.9(b) Speed drive 120.6(e), 120.9(b), 140.4(c)1, 140.4(k)6, 160.4(e), 170.2(c)4I Speed fan 120.6(a)4, 120.6(a)8, 120.6(b)1, 150.0(o), 160.2(b)2 Ventilation 150.0(o), 160.2(b)2A Vending Machine 140.6(a)3J, K, L Vent Damper 110.2(d), 110.2(f) Vented Attic 150.0(a), 150.0(g), 150.2(b)1J, 160.1(a), 160.1(d), 180.2(b)1 Vented Range Hood 150.0(o), Table 150.0-E, 150.0(v), 160.2(b)2B, Table 160.2-E Ventilated Attic 150.1(c)9, 170.2(c), 180.2(a)1 Ventilation 120.1, 140.4(b)4, 150.0(o), 160.3(d)2 Air 120.1(d), 120.2(e), 130.1(f), 140.4(e), 140.4(m), 140.9(b), 150.0(o), 150.1(b), 150.2(a)2C, 160.2(b)2B, 160.2(c), 160.5(b), 170.1(d), 170.2(c), 180.1(a), 180.3(a) And indoor air quality 120.1, 150.0(o), 160.2(b)2 Cooling 150.1(b)3, 150.1(c)12, 150.2(a), 170.1(d) Dampers 150.0(m)8, 160.3(b) Device 10-103(b), 120.1(d), 160.2(c)5 Doors 120.6(f) Fan 120.6(f), 150.2(b)1L, 180.2(b) Load 140.4(b)4, 170.2(c) Only 120.1(h)
CPC § 503.3.6 Medium relevance — show source text
Pool covers . . . . . . . . . . . . . . . . . . . . . . . . . . .L 503.3.6
Service hot water . . . . . . . . . . . . . . . . . . . . . .L 503.3.3
Tracer wire . . . . . . . . . . . . . . . . . . . .604.10.1, E 403.8.4 INTERCEPTING HOPPERS OR SINKS . . .(see Receptors) INTERCEPTOR (CLARIFIER)
Abandoned . . . . . . . . . . . . . . . . . . . . . . . . . . . .1014.3.7
Auto wash racks . . . . . . . . . . . . . . . . . . . . . . . . . .1011.0
Bottling establishments . . . . . . . . . . . . . . . . . . . .1013.0 Cleanouts, location . . . . . . . . . . . . . . . . . . . . . . . .707.7
Commercial and industrial laundries . . . . . . . . . .1012.0
Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .211.0
Grease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1014.0
Industrial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1009.0
Oil and flammable liquid . . . . . . . . . . . . . . . . . . . .1017.0 Packing establishments . . . . . . . . . . . . . . . . . . . .1010.0
Sand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1016.0
Slaughterhouses . . . . . . . . . . . . . . . . . . . . . . . . .1010.0
Vents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .902.1
INTERMIXING OF
METALS PROHIBITED . . . . . . . . . . . . . . . . .310.6, 604.1
INVERT, DEFINITION . . . . . . . . . . . . . . . . . . . . . . . . . .211.0
IRON PIPE SIZE (IPS) PIPE . . . . . . . . . . . . . . . . . . . .302.0
IRRIGATION FIELD
Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . .1504.5
Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .211.0
CPC § 1015.0 Medium relevance — show source text
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
1101.1 Applicability . . . . . . . . . . . . . . . . . .205
1101.2 Where Required . . . . . . . . . . . . . .205
1101.3 Storm Water Drainage to Sanitary Sewer Prohibited . . . . . .205
1101.4 Material Uses . . . . . . . . . . . . . . . .205
Table 1101.4.6 Materials for Subsoil Drainpipe and Fittings . . . . . . . . . . . . . . . . . .205
1101.5 Expansion Joints Required . . . . . .205
1101.6 Subsoil Drains . . . . . . . . . . . . . . .205
1101.7 Building Subdrains . . . . . . . . . . . .206
1101.8 Areaway Drains . . . . . . . . . . . . . .206
1101.9 Window Areaway Drains . . . . . . .206
1101.10 Filling Stations and Motor Vehicle Washing Establishments . . . . . . . . . . . . . . .206
1101.11 Paved Areas . . . . . . . . . . . . . . . . .206
1101.12 Roof Drainage . . . . . . . . . . . . . . .206
1101.13 Cleanouts . . . . . . . . . . . . . . . . . . .207
1101.14 Rainwater Sumps . . . . . . . . . . . . .207
CPC § 1011.0 Medium 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 § 1015.4 Medium relevance — show source text
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. The outlet pipe shall be the same size as the inlet pipe of the sand interceptor, the minimum being 3 inches (80 mm), and the baffle shall have two openings of the same diameter as the outlet pipe and at the same invert as the outlet pipe. These openings shall be staggered so that there cannot be a straight line flow between the inlet pipe and the outlet pipe. The invert of the inlet pipe shall be no lower than the invert of the outlet pipe.
The sand interceptor shall have a minimum dimension of 2 square feet (0.2 m [2] ) for the net free opening of the inlet section and a minimum depth under the invert of the outlet pipe of 2 feet (610 mm).
For each 5 gpm (0.3 L/s) flow or fraction thereof over 20 gpm (1.26 L/s), the area of the sand interceptor inlet section is to be increased by 1 square foot (0.09 m [2] ). The outlet section shall at all times have a minimum area of 50 percent of the inlet section.
The outlet section shall be covered by a solid removable cover, set flush with the finished floor, and the inlet section shall have an open grating, set flush with the finished floor and suitable for the traffic in the area in which it is located.
1016.4 Separate Use. Sand and similar interceptors for every solid shall be so designed and located as to be readily accessible for cleaning, shall have a water seal of not less than 6 inches (152 mm), and shall be vented.
1017.0 Oil and Flammable Liquid Interceptors.
1017.1 Interceptors Required. Repair garages and gasoline stations with grease racks or grease pits, and factories that have oily, flammable, or both types of wastes as a result of manufacturing, storage, maintenance, repair, or testing processes, shall be provided with an oil or flammable liquid interceptor. Floor drains in such locations shall be connected directly to oil and flammable liquid interceptors.
CPC § 1007.2 Medium relevance — show source text
1007.2 Trap Seal Primers. Potable water supply trap seal primer valves shall comply with ASSE 1018. Drainage or electronic design type trap seal primer devices shall comply with ASSE 1044 or IAPMO PS 76.
1008.0 Building Traps. 1008.1 General. Building traps shall not be installed except where required by the Authority Having Jurisdiction. Each building trap where installed shall be provided with a cleanout and with a relieving vent or fresh-air intake on the inlet side of the trap, which needs not be larger than one-half the diameter of the drain to which it connects. Such relieving vent or fresh-air intake shall be carried above grade and terminate in a screened outlet located outside the building.
1009.0 Interceptors (Clarifiers) and Separators.
1009.1 Where Required. Interceptors (clarifiers) (including grease, oil, sand, solid interceptors, etc.) shall be required
by the Authority Having Jurisdiction where they are necessary for the proper handling of liquid wastes containing grease, flammable wastes, sand, solids, acid or alkaline substances, or other ingredients harmful to the building drainage system, the public or private sewer, or to public or private sewage disposal. A list of acceptable interceptor standards is referenced in Table 1009.1.
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.
CPC § 901.0 Medium relevance — show source text
H 901.0 Commercial or Industrial Special Liquid- Waste Disposal.
H 901.1 Interceptor. Where liquid wastes contain excessive amounts of grease, garbage, flammable wastes, sand, or other ingredients that affect the operation of a private sewage disposal system, an interceptor for such wastes shall be installed.
H 901.2 Installation. Installation of such interceptors shall comply with Section 1009.0 of this code, and their location shall comply with Table H 101.8 of this appendix. H 901.3 Sampling Box. A sampling box shall be installed where required by the Authority Having Jurisdiction. H 901.4 Design and Structural Requirement. Interceptors shall be of approved design and be not less than two compartments. Structural requirements shall comply with Section H 501.0 of this appendix.
H 901.5 Location. Interceptors shall be located as close to the source as possible and be accessible for servicing. Necessary manholes for servicing shall be at grade level and be gastight.
H 901.6 Waste Discharge. Waste discharge from interceptors shall be permitted to be connected to a septic tank or other primary system or be disposed into a separate disposal system. H 901.7 Design Criteria. A formula shall be permitted to be adapted to other types of occupancies with similar wastes. (See Chart H 901.7)
H 1001.0 Inspection and Testing. H 1001.1 Inspection. Inspection requirements shall comply with the following:
(1) Applicable provisions of Section 105.0 of this code and this appendix shall be required. Plans shall be required in accordance with Section 103.3 of this code.
(2) System components shall be properly identified as to manufacturer. Septic tanks or other primary systems shall have the rated capacity permanently marked on the unit.
(3) Septic tanks or other primary systems shall be installed on dry, level, well-compacted soil.
(4) Where design is predicated on soil tests, the system shall be installed at the same location and depth as the tested
area.
H 1001.2 Testing. Testing requirements shall comply with the following:
(1) Septic tanks or other primary components shall be filled with water to flow line before requesting an inspection. Seams or joints shall be left exposed (except the bottom), and the tank shall remain watertight.
(2) A flow test shall be performed through the system to the point of effluent disposal. All lines and components shall
CHART H 901.7
RECOMMENDED DESIGN CRITERIA
GREASE AND GARBAGE, COMMERCIAL KITCHENS Number of meals per peak hour x Waste flow rate [1] x Retention time [2] x Storage factor [3] = (Interceptor size liquid capacity)
SAND-SILT OIL, AUTO WASHERS vehicles Number of per hour x Waste flow rate [1] x Retention time [2] x Storage factor [3] = (Interceptor size liquid capacity)
SILT-LINT GREASE, LAUNDRIES, LAUNDROMATS
Number of x 2 cycles per x Waste flow x Retention time [2] = Storage factor [3] = Interceptor size machines hour rate [1] (liquid capacity)
Notes: 1 For waste flow rate see Table H 201.1(4). 2 Retention Times:
CPC § 1009.1 Medium 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)
196 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
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.
Frequently asked questions
Can I connect the interceptor vent to the building sanitary vent?
No. The interceptor must be vented on the sewer side and must not connect to a flammable vapor vent; separation and independent venting to the outer air is required per § 1017.3(3) and (1) .
Is a manufacturer's rating required?
Manufactured interceptors that are rated must be stamped/labeled with the full discharge rate; if you use a rated unit, size by the manufacturer rating (must be ≥ incoming flow). If no rating exists, follow the dimensional and capacity minimums in § 1017.4(2) .
What if the interceptor overflows — where must overflow go?
If an interceptor has an overflow, the overflow must be piped (≥ 2 in) to an approved waste oil tank with a minimum 550‑gal capacity and meeting AHJ requirements; tank must have a 2‑inch pump‑out at grade and a 1½‑inch vent terminating not less than 10 ft above grade (§ 1017.3(5)) .
Are sidewall vent terminations allowed?
Yes — but a flammable vapor vent that discharges through a sidewall must terminate at an approved location not less than 10 feet above the adjacent level (§ 1017.3(2)) .
Who decides sizing when vehicle counts exceed the table?
When more than 10 vehicles are involved, the Authority Having Jurisdiction (AHJ) determines required interceptor size per § 1017.4(2)(b) .
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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