It is important that a grease trap is cleaned on a regular basis to ensure it stays in good working order with minimum odours. In routine operations, grease will float and settle at the top of the chamber and the solids will settle at the bottom. The grease trap should be cleaned when the grease accumulates to around 25% of capacity. This is achieved by emptying fully and cleaning, prior to refilling with fresh water. 

The above photos show a trap requiring attention