Hydromechanical Grease Interceptors: Ratings, Labels, and Local Approval

Prepared by GreaseTrapLocator · Fact review: August 9, 2026

The City of Toronto describes a hydromechanical grease interceptor as a small, point-of-source unit. That is a Toronto/Ontario example, not a universal definition. For another project, use the responsible local authority’s requirements and the documentation for the exact proposed product. City of Toronto guidance

What a hydromechanical interceptor label can tell you

Toronto’s installation guidance describes a hydromechanical grease interceptor as a small, point-of-source unit that is typically installed under a kitchen sink and can also be installed in-ground under a floor. This is a Toronto/Ontario example, not a rule for every location. City of Toronto guidance

For point-of-source installations in Toronto, the City says the interceptor must meet CSA B481.1:22 as required by the Ontario Building Code. The City says a qualifying label shows the flow rating, removal efficiency, maximum containment capacity, and inlet size. Those fields describe different characteristics. They should not be converted into one another or used as a shortcut for selecting equipment for another project. City of Toronto guidance

Keep ratings and capacity measurements separate

Flow rating, maximum grease containment capacity, and liquid capacity are separate measurements. A product listing can show all of them without making them interchangeable. For example, Schier’s GB2-C product page lists a 35-GPM flow rating, 130-pound grease capacity, and 20-gallon liquid capacity for that named model. Those are specifications for the GB2-C only; they do not select a size for another model, menu, or location. Schier GB2-C product information

Do not use seats, meals, cuisine, or a generic gallon chart to convert one of those measurements into another. The local approval process and the documents for the exact proposed product are the appropriate basis for a project decision.

Use local approval before choosing equipment

Local authorities can use different approval processes and different design inputs. Austin Water, for example, tells applicants not to purchase a grease trap or interceptor before obtaining building-plan approval and an Industrial Waste approval letter that specifies the required size and design. Austin’s requirements apply in Austin; the point is that the local authority’s process controls the local project. Austin Water sizing and design criteria

Before selecting a hydromechanical interceptor, collect the local approval requirements, the proposed product’s current label and installation documentation, the fixtures proposed for connection, and the approved project plan. This page does not provide installation or service instructions.

Installation and access are project-specific

Toronto requires a building permit to install or replace a grease interceptor and says the installed unit must be easily accessible for maintenance and inspection. These are Toronto requirements, not universal requirements. The same guidance identifies fixtures that must, may, or must not connect in that local program. City of Toronto guidance

For any proposed installation, follow the applicable local rules, approved plans, and the exact manufacturer documentation. A manufacturer’s instructions can also defer to local requirements: Watts states that local building or plumbing codes may require modifications and that local codes should be followed. That instruction applies to the named Watts products covered by its manual. Watts installation instructions

Questions to take to local review

• Which local authority approves the proposed system?
• Which fixtures are included in the approved project?
• Which current product label, certification, drawings, and installation documents must be submitted?
• What access, inspection, and record requirements apply at this location?

Frequently asked questions

What is a hydromechanical grease interceptor?

Toronto describes it as a small, point-of-source grease interceptor that is typically installed under a kitchen sink and can also be installed in-ground under a floor. That description is a Toronto/Ontario example; local rules and the exact product documentation govern another project.

Does a flow rating tell me which interceptor to buy?

No. A flow rating is one label field. Toronto also identifies removal efficiency, maximum containment capacity, and inlet size as separate fields. The local approval process and the documents for the exact proposed product determine a project decision.

Are flow rating, grease capacity, and liquid capacity the same measurement?

No. Schier’s GB2-C listing separately publishes a 35-GPM flow rating, 130-pound grease capacity, and 20-gallon liquid capacity for that named model. Those values should not be converted into a generic sizing rule.

Can I rely on a national installation rule?

No. Local requirements differ. Toronto, for example, requires a building permit and accessible installation in its program, while Austin directs applicants to obtain local approval before purchasing equipment. Those examples are local, not national rules.

Does this page explain how to install or service an interceptor?

No. Installation and service work must follow the applicable local requirements, approved project documents, and the current instructions for the exact product.

Sources

• City of Toronto — Grease Interceptor Installation (modified May 14, 2026; Toronto/Ontario only).
• Schier Products — GB2-C Grease Interceptor (accessed August 9, 2026; named model only).
• Austin Water — Grease Trap Sizing & Design Criteria (accessed August 9, 2026; Austin only).
• Watts — Grease Interceptors Installation Instructions (accessed August 9, 2026; named product families only).