Across the DMV, restaurants must clean their grease trap before it reaches 25% of capacity — the 25% rule. Baltimore City adds a hard 90-day minimum. This guide breaks down the rules in DC, Maryland, and Virginia and explains what really sets your pumping frequency.
How often should a restaurant pump its grease trap?
There is no single calendar that fits every kitchen. A small indoor trap under a busy fryer line can hit 25% in two weeks; a large outdoor interceptor at a low-volume café might take two months. The rule is about the fill level, not the date — which is why a good hauler sets your cadence to your actual fill rate.
The DMV rules, side by side
| Where | Cleaning trigger | Records |
|---|---|---|
| Washington, DC | Maintain interceptor per DC Plumbing Code; register in DC Water's FOG BMP portal; service by a DOEE-licensed hauler | 3 years on site |
| Baltimore | At least every 90 days and before 25% capacity | 3 years |
| Northern Virginia (Fairfax & others) | Before 25% full of grease and solids; permitted contractor | 3 years |
Each city runs its own FOG program, but the underlying logic is identical: keep the trap below a quarter full and keep the paperwork. For the city-specific detail, see our pages for Washington, DC, Baltimore, and Northern Virginia.
What actually determines your frequency
Three factors drive how often you'll need a pump-out: how much you fry (fryer-heavy menus produce more FOG), your trap's size relative to that volume, and how well your kitchen keeps food solids and oil out of the drain in the first place. Scraping plates and never pouring used fryer oil down the sink both stretch the interval.
How GreaseGiant sets your schedule
We size the cadence to your fill rate, not a generic calendar — then adjust as we learn your real flow. Every visit is a full pump-out with the baffles scraped and a signed manifest left on site, so you stay under 25% and keep three years of records without thinking about it. See how grease trap cleaning works, or bundle it with used cooking oil pickup on one invoice.
Frequently asked questions
What is the 25% rule for grease traps?
The 25% rule means you must clean a grease trap before fats, oils, grease, and settled solids reach 25% of the trap's total liquid depth or capacity. It's the standard trigger used by DC Water, Baltimore City, and Virginia localities. Past 25%, grease starts escaping into the sewer line.
Can I just clean my grease trap once a year?
Almost never. Annual cleaning fails the 25% rule for virtually every active kitchen. Baltimore City sets a 90-day minimum, and most fryer-heavy restaurants need monthly or biweekly service. Annual-only cleaning is how traps overflow and lines clog.
Who is responsible if my grease trap causes a sewer backup?
You are. The food service establishment is responsible for keeping its trap maintained, and a backup traced to an over-full trap can mean fines plus cleanup costs. A documented cleaning schedule and manifests are your protection.