Guide
How often should a grease trap be cleaned? Honest intervals by kitchen
Updated
There is no statutory service interval for grease traps. The honest answer is that throughput decides: a fried-chicken shop fills a trap many times faster than a sandwich bar. Here is how to find your interval instead of guessing it.
Common intervals by kitchen type
| Kitchen | Common interval |
|---|---|
| High-volume frying: takeaways, fried chicken, busy restaurant kitchens | Every 4–8 weeks, sometimes more often |
| Busy general kitchens: pubs, hotels, mid-size restaurants | Every 1–3 months |
| Lower-fat or lower-volume sites: cafes, sandwich bars, small canteens | Every 3–6 months, on evidence the trap can take it |
Treat the table as a starting point, not a rule. Two kitchens with the same signage can produce wildly different fat, oil and grease loads depending on menu, covers and how disciplined the pot wash is.
The working rule: watch the fill, not the calendar
- The quarter-full rule of thumb: a widely used industry guide says a trap should be serviced before the grease and solids layer reaches about a quarter of the trap's liquid depth; past that, separation performance falls away and the trap starts passing grease downstream.
- Warning signs you've left it too long: smell from the trap or drains, slow-draining sinks, visible grease at the outlet, and gurgling. Any of these means book the visit now, not at the next scheduled date.
- Undersized traps need more visits: if your trap needs emptying monthly and still smells, the trap may be too small for the kitchen rather than the interval too long, sizing to BS EN 1825 is the fix, see the regulations guide.
Finding your interval in two services
- Start at the cautious end for your kitchen type, monthly for heavy frying, quarterly for lighter use.
- Have the firm measure the fill each visit. A good operator records how full the trap was; two or three data points show your real fill rate.
- Set the schedule from the data and revisit it when the menu or covers change. A contract priced on the right interval beats both over-servicing and emergency callouts, get contract quotes with your real numbers.