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Commercial plumbing: codes, grease, backflow and permits
Restaurants, offices, shops and apartment buildings face plumbing rules most homes never see. Here are the main ones, and what to ask a commercial plumber.
The short answer
Commercial plumbing is governed by a plumbing code your state or city adopts (usually the ICC’s International Plumbing Code or IAPMO’s Uniform Plumbing Code). Food businesses typically need a grease trap or interceptor on a pumping schedule; buildings with backflow assemblies need a yearly test by a certified tester; and commercial plumbing work usually needs a permit pulled by a licensed contractor, sometimes with plan review first.
Which plumbing code applies
Two model codes dominate. The International Code Council says its International Plumbing Code sets minimum requirements for plumbing systems using prescriptive and performance-related provisions. IAPMO develops the Uniform Plumbing Code using ANSI-accredited consensus procedures, with representatives from across the industry. States and cities adopt one of them, often with local amendments – your building department will tell you which edition is in force.
Grease traps and interceptors (restaurants and food service)
EPA reports that grease is the most common cause of reported sewer blockages – 47 percent – and that interceptors must be designed and sized so grease can cool and separate. Cities enforce this through fats, oils and grease (FOG) programs:
- Tempe, Arizona requires every food service establishment to install an indoor grease trap or an outdoor grease interceptor; traps are serviced monthly and interceptors quarterly, or more often if needed, with pump-out records kept on site.
- Los Angeles requires food service establishments that generate grease waste to hold an Industrial Wastewater Permit and operate approved grease removal devices.
Backflow testing
Backflow is water flowing backward into the drinking water supply, which can carry contaminants, as Troy, Michigan explains. Commercial properties usually have testable backflow assemblies:
- Portland, Oregon requires assemblies to be tested at least once a year by a state-certified tester, and retested after repairs; owners schedule the tests.
- Troy, Michigan requires commercial backflow testing once a year by a licensed plumber with ASSE backflow tester certification.
See our backflow testing guide.
Permits and plan review
In Portland, plumbing work at a commercial site must be permitted and done by a licensed plumbing contractor. Some cities review plans before issuing the permit: Duluth, Minnesota requires plumbing plan review for projects with more than 25 openings, food facilities, state-licensed facilities and public buildings. Build that review time into the schedule.
Accessible fixtures (ADA)
Public and commercial restrooms must meet the ADA Standards. The U.S. Access Board’s guide says accessible lavatories may be no higher than 34 inches to the rim or counter, pipes under accessible sinks must be insulated or configured to prevent contact, and faucet controls must work with one hand, without tight grasping, pinching or twisting, and with no more than five pounds of force.
Choosing a commercial plumber
- Use the Commercial filter on any city page in this directory – it shows businesses whose own website says they do commercial work.
- Ask for their commercial license class and insurance limits, and who handles permits and plan review.
- For food service, ask whether they install and service grease interceptors; for backflow, whether they hold the tester certification your utility requires.
- Ask about after-hours response – a commercial outage costs more by the hour.
Find a plumber near you
Local plumbers by metro area, listed A to Z with phone numbers, services and emergency options.
Questions
What plumbing code applies to commercial buildings?
Usually the International Plumbing Code (ICC) or the Uniform Plumbing Code (IAPMO), as adopted – often with amendments – by your state or city. Your building department can confirm the edition.
Do restaurants need a grease trap?
Most cities require food service establishments to have a grease trap or grease interceptor and to pump it on a schedule. Tempe, Arizona, for example, requires one or the other for every food service establishment.
How often is commercial backflow testing required?
Commonly once a year, by a certified tester, and again after repairs. Portland, Oregon and Troy, Michigan both require annual testing.
Who can do commercial plumbing work?
Typically a licensed plumbing contractor, who also pulls the permit. Check the license on your state’s official lookup before hiring.
Related guides
Sources
Facts and figures in this guide come from these official and manufacturer sources, checked October 2026:
- International Code Council – International Plumbing Code
- IAPMO – Uniform Plumbing Code
- EPA – Controlling fats, oils and grease discharges (PDF)
- City of Tempe, AZ – Fats, oils and grease program
- LA Sanitation & Environment – Fats, oils and grease
- Portland Water Bureau – Backflow testing requirements
- City of Troy, MI – Backflow assembly testing
- Portland Permitting & Development – Commercial plumbing permits
- City of Duluth, MN – Commercial plumbing permits and plan review
- U.S. Access Board – Guide to the ADA Standards: lavatories and sinks
Updated October 2026 by the Plumbers Pages editorial team. General information for homeowners, not professional advice – codes and equipment differ, so follow your product’s manual and local rules. When gas, electricity, sewage or anyone’s safety is involved, call 911, your utility or a licensed plumber. How we write our guides · Plumbing glossary
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