Why Grease Trap Size Matters
Installing an undersized grease trap is one of the most common compliance mistakes made by new F&B operators in the UAE. Even if the unit is a DM-approved model, if its rated capacity is lower than the flow generated by your kitchen, FOG will carry over into the municipal drainage system — and Dubai Municipality inspectors can issue the same fines as if no trap were installed at all.
Getting the size right from the start avoids costly retrofits, access surcharges for in-ground replacements, and the risk of failing your first DM inspection. Learn how to avoid costly mistakes when buying a grease trap before making your purchase decision.
The DM Sizing Formula
Dubai Municipality specifies minimum grease interceptor capacity using a flow-rate calculation defined in DM Circular No. 207 of 2012 (Food Safety Department). The formula takes three inputs:
- Meals served per day (M) — total covers across all sittings
- Waste flow factor (W) — standardised litres of wastewater generated per meal: 8 litres for a full-service restaurant; 4 litres for a fast food / QSR; 2 litres for a cafe or bakery
- Retention time (R) — the minimum time wastewater must remain in the trap for adequate FOG separation: 2.5 minutes for standard units
The required capacity in litres = M x W x (R / 60)
Example: A full-service restaurant serving 300 meals per day: 300 x 8 x (2.5 / 60) = 100 litres minimum capacity. A safety margin of 25–50% is recommended, putting a 150-litre unit as the practical minimum.
Quick-Reference Sizing Table
| Kitchen Type | Meals / Day | Minimum Capacity | GTC Recommended Unit |
|---|---|---|---|
| Small cafe / juice bar | Up to 50 | 50 L | 50–100 L under-sink |
| Mid-size cafe / QSR | 50 – 150 | 50 – 80 L | 100–200 L under-sink |
| Full-service restaurant | 150 – 300 | 100 – 200 L | 200–500 L in-ground |
| Large restaurant / food court stall | 300 – 600 | 200 – 400 L | 500–1,000 L in-ground |
| Hotel secondary kitchen | 200 – 400 | 150 – 300 L | 500 L in-ground |
| Hotel main kitchen | 500+ | 400 L+ | 1,000–3,000 L in-ground |
| Cloud kitchen (multi-brand) | 200 – 600 | 150 – 400 L | 500–1,000 L in-ground |
| Mall food court (shared central) | 1,000+ | 1,000 L+ | 3,000–10,000 L engineered |
These figures are indicative. DM requires a site-specific calculation. GTC provides a free survey and size recommendation for all new installations.
What Happens If the Trap Is Undersized?
An undersized trap fills faster, meaning the grease layer and sediment reach the 25% overflow threshold before your next scheduled cleaning. In practice this means:
- FOG bypasses the outlet baffle and enters the municipal sewer — a direct DM violation with fines from AED 5,000 to AED 50,000
- More frequent emergency cleanings are required, significantly increasing your annual cost
- Drain backups into the kitchen floor or sink are more likely — see our emergency drain line unblock service if this happens
- DM may require a full replacement at your expense within a specified remediation period
What About Oversizing?
A trap that’s too large for the actual flow volume has the opposite problem: wastewater moves through too slowly, FOG accumulates in layers that become difficult to remove with standard pump-out equipment, and decomposing grease produces hydrogen sulphide odours. Oversizing wastes capital on a larger unit and can actually increase cleaning costs for very large in-ground interceptors. A bio-dosing system can help manage FOG build-up in oversized traps by introducing bacteria that break down grease between pump-outs.
Get a Free Size Survey from GTC
Rather than guessing, GTC will carry out a free site survey and calculate the correct unit size before any purchase decision. We supply and install DM-approved units from 50 litres to 10,000+ litres, and handle the DM permit application and inspection sign-off on your behalf. For stainless steel options preferred by high-end kitchens, read about how stainless steel grease traps improve kitchen safety. For resort and hotel kitchens, see the best grease trap solutions for UAE resort businesses.
View all our services, check our FAQs, or call +971 58 570 7110 to arrange a survey.