# Grease Trap / Interceptor Requirements for a Commercial Kitchen

> Plumbing code — not the health code — is what forces a grease interceptor: any fixture with grease-laden waste needs one, sized by a 30-minute retention formula. What the code requires, quoted, and why a home kitchen is exempt.

Updated: 2026-09-11. Source: KitchenRisk — https://kitchenrisk.com/guides/grease-trap-interceptor-requirements-restaurant/ (claims cited to primary sources; see /methodology/).

Short answer: if a fixture in your kitchen discharges fats, oils, or grease — a pot sink, prerinse sink, wok station, or the floor drains a kettle empties into — the plumbing code requires it to run through a grease interceptor or automatic grease removal device. It is the plumbing code, not the health code, that actually mandates this, and a private home kitchen is explicitly exempt. On a used space, whether a properly sized interceptor already exists is a five-figure question you want answered before you sign.

## When an interceptor is required

The 2021 International Plumbing Code §1003.3.1 sets the trigger by what the fixture discharges, and names restaurants directly:

> "A grease interceptor or automatic grease removal device shall be required to receive the drainage from fixtures and equipment with grease-laden waste located in food preparation areas, such as in restaurants, hotel kitchens, hospitals, school kitchens, bars, factory cafeterias and clubs." — 2021 IPC §1003.3.1

And it draws the line at the home kitchen — which is exactly why a residential setup never needed one and a commercial one always does:

> "A grease interceptor or an automatic grease removal device shall not be required for individual dwelling units or any private living quarters." — 2021 IPC §1003.3.4

## How it’s sized: the 30-minute rule

Interceptors are not one-size. A gravity grease interceptor is sized off your peak flow and a fixed retention time:

> "The required capacity of gravity grease interceptors … shall be determined by multiplying the peak drain flow into the interceptor in gallons per minute by a retention time of 30 minutes." — 2021 IPC §1003.3.7

Hydromechanical (smaller, under-sink) units are instead sized off a flow-rate/retention-capacity table (IPC Table 1003.3.5.1). The practical point for a buyer: an interceptor that was sized for the previous tenant’s smaller line may be undersized for what you plan to run, and up-sizing means plumbing work, not a swap.

## The health-code backstop: it has to be cleanable

Where the plumbing code decides whether you need one, the FDA Food Code adds a placement rule so it can actually be maintained. §5-402.12:

> "If used, a grease trap shall be located to be easily accessible for cleaning." — FDA Food Code 2022, §5-402.12

An interceptor buried under new equipment or behind a wall — a common "saved money on the build" shortcut in a used space — is both a plumbing and a health-code problem, and a maintenance nightmare that leads to backups.

## What to check before you buy a space

- Is there an interceptor at all, and is it sized for your planned peak flow (not the last tenant’s)?

- Is it accessible for cleaning, per the FDA rule — or is it buried?

- Local rules override. Many jurisdictions use the Uniform Plumbing Code (UPC) instead of the IPC, and cities set their own interceptor sizing and pump-out schedules through the sewer authority. Confirm the local requirement before you build.

The grease-producing appliances that drive this are the same ones that force a Type I hood — see [Type I or Type II hood?](/guides/type-i-vs-type-ii-hood/) — and the sinks an inspector requires are in [the sink and dish-machine guide](/guides/sinks-and-dish-machine-inspector-requires/). Price the equipment against its documented failure modes: [browse the model records](/brands/).

IPC §1003 text from the 2021 International Plumbing Code via ICC Digital Codes; the FDA quote is from the FDA Food Code 2022. Codes are adopted and amended locally (and many jurisdictions use the UPC) — confirm your jurisdiction’s current requirement. General information, not code-compliance or legal advice.