Grease Trap / Interceptor (BWSC requirement): Boston restaurant guide
Boston Water and Sewer Commission — Enforcement
What it is
BWSC requires grease traps or interceptors on sewer lines for all restaurants and commercial food handling businesses. Grease-producing fixtures (pot sinks, dishwasher pre-rinse, woks, floor drains, automatic hood washers) must drain through one.
When a restaurant needs it
Every restaurant. Designed and installed during build-out; maintained for as long as you operate.
How to apply
Your engineer or plumber includes the trap in the plumbing design; grease trap submissions go to BWSC Enforcement for review and approval, and the licensed plumber installs it under the ISD plumbing permit.
Documents you’ll need
- Plumbing plan showing trap/interceptor and connected fixtures
- Manufacturer specs and sizing
- Grease Control Log (kept on site)
Good to know
Don't install garbage disposals on fixtures that drain to the trap. BWSC Enforcement inspects and enforces a 100 mg/L grease discharge limit (617-989-7299).
Official source
BWSC — commercial kitchen grease trap guidelines · BWSC — sewer requirements
Answer a few questions about your space and get every permit in order, with a timeline, a cost range, walkthroughs, and every application filled in for you to sign with Open.
Last reviewed 2026-10-06. Guidance only, not legal advice.