What does Mesa's commercial plumbing plan review checklist require?

The nine-page checklist says its references follow the 2024 International Plumbing Code, building, residential, fuel gas, fire, energy and mechanical codes, the Mesa Administrative Code and NFPA standards, with Mesa amendments marked "M". IPC Sections 101.4 through 115.4 are deleted, and administrative rules come from Mesa City Code Title 4, Chapter 1. The 2024 IPC Appendices C and E are adopted. Its sections run as follows:

• Administrative and general. A project narrative, site address, vicinity map and site plan. Sealed sheets need a legible seal with the registrant's license number and signature date.
• Plumbing facilities. Occupant load or minimum fixtures under IPC Table 403.1, separate toilet facilities for each sex with an exception for small occupancies of 25 or less, an accessible family or assisted-use toilet in assembly and mercantile occupancies with six or more water closets, toilet access that does not pass through a kitchen, storage or closet, and drinking fountains within 500 feet, with an exception for occupant loads of 50 or less. Service sinks are not required in Groups B and M where the occupant load does not exceed 100 persons (Mesa amendment to IPC 403.1).
• Low-flow fixtures. Flow rates must meet the Mesa version of IPC Table 604.4. Underground nonmetallic water pipe of 2 inches or more needs insulated copper tracer wire or an approved conductor, 14 AWG minimum.
• Civil and site plan. Water meter, service, sewer and storm drainage sizes and locations on the civil sheets must match the plumbing plans, and required grease or sand-oil interceptors and their locations must be shown.
• Water service and distribution. Specialty fixtures limited to 120°F, tempered water 85° to 120°F at hand sinks, emergency showers and eyewash stations, water heater 18 inches above an ignition source, a safe pan and drain line, a temperature and pressure relief line termination, sizing calculations, a pressure reducing valve above 80 psi, recirculation or insulated hot water lines no longer than 50 feet, insulation, thermal expansion control and combustion air.
• Drainage and vents. Trap and drain sizing, slopes, cleanouts, three-compartment sinks and independent waste receptors in food handling, oil separators at repair garages, car washes and factories with oily waste, hydraulic elevator pits (with an exception if an approved alarm system is installed), interceptors and pipe material identification, plus vent sizing and terminations.
• Backflow prevention. Protection at potential cross connections, kitchen equipment, carbonators, medical equipment and dental vacuum pumps. The list states that "Backflow devices shall be reviewed and approved before installation" and points to the city backflow group. See 8-1-6.
• Roof drainage. Sizing calculations, scupper dimensions, separate endpoints for primary and secondary drains, and no drainage over public walking surfaces.
• Interceptors. Grease interceptors reviewed and approved before installation, through Industrial Pretreatment. See 8-4-22.

The checklist ends with worked samples for fixture counts and roof drain sizing.

Under Mesa City Code 4-1-4(I), plans and calculations go in with each application, prepared by a registered design professional as state law requires. Submittals are screened for completeness and code compliance before acceptance, and incomplete ones, or ones with readily apparent code violations, can be returned. Deferred submittals are allowed for items such as fire sprinklers, kitchen hoods and elevators, but the code lists "building plumbing systems" among the items that shall not be deferred.

• M-IPC. The 2024 International Plumbing Code as amended by Mesa.
• Screening. The intake check that decides whether a submittal is complete enough to review.
• Deferred submittal. A portion of the design filed after the application with the director's prior approval. Building plumbing systems are not eligible.
• Civil sheets. The site and utility drawings that show meter, water service, sewer and storm drain.

Design professionals and contractors preparing plumbing drawings for a commercial permit in Mesa, including tenant improvements. Restaurant, medical and industrial tenants hit more of the list, because of interceptors, medical gas and vacuum, and cross connections.

A restaurant tenant improvement. The set shows the three-compartment sink, the grease interceptor and its location on the civil sheet, and a backflow assembly at the carbonator. Each of those is a checklist line, so the reviewer finds it where expected.

An office remodel. A new restroom cluster is sized from the occupant load. Under the checklist, occupancies of 25 or less can skip separate facilities by sex.

The edge case. The checklist's own sample treats service sinks differently from the amendment line. The text says service sinks are not required for Groups B and M when the occupant load is 100 or less, while the sample note refers to an occupant load of 15 or fewer. Check with a plans examiner which reading applies to a borderline occupant load.

1. 1Work through the checklist section by section against your drawing set before submitting.
2. 2Make sure the civil sheets match the plumbing plans for meter, service, sewer and storm drain.
3. 3Show interceptor and backflow assemblies on the plans, since both must be approved before installation.
4. 4Do not plan to defer plumbing to a later submittal.
5. 5Have the design professional's seal, license number and signature date legible on every sealed sheet.

• "Plumbing can be a deferred submittal." The code says building plumbing systems shall not be deferred.
• "The civil set and the plumbing set are separate." The checklist requires the sizes and locations to match.
• "The interceptor can be sorted out at inspection." It has to be reviewed and approved before installation.
• "The checklist is the whole code." It is a review aid built on the 2024 IPC with Mesa amendments.