Greasy waste that accumulates in the grease trap must be removed regularly. The frequency of cleaning will vary depending on the type of food served and how active your business is. Regular cleaning keeps a grease trap working properly and will prevent clogging in kitchen drains and pipes.

Inspect the grease trap at least every three days and clean it promptly if the contents show the top 30% of liquid depth occupied by greasy waste. Every grease trap is different and must be inspected regularly to determine if cleaning is required.

If very little waste builds up in one week or if the surface layer is liquid oil only, the grease trap may not be functioning effectively. Check for proper design as outlined in this booklet and modify or replace the trap if necessary.

• Small grease traps may be cleaned by hand by scooping the top waste layer into a watertight bag or container. It is not necessary to empty the grease trap completely; remove only semi-solid layer of greasy waste on the top of the liquid surface.
  
  
• Clean the trap at a time when wastewater will not be passing through it. Take care not to leave lumps of grease in the trap as this may lead to clogging.
  
  
• Handle the greasy waste carefully to avoid contamination of food preparation or storage areas.
  
  
• Warning signs and safety barriers should be erected around under-floor and large grease traps during cleaning.
  
  
• Replace grease trap covers promptly and clean the surrounding area with a disinfectant.
  
  
• The grease trap waste container should be tightly sealed and disposed of with other kitchen refuse.
  
  
• DO NOT dispose of the grease trap waste to toilet, gulleys, surface channels or manholes.
  
  
• Record maintenance activities in a log book.

Clogging of the inlet or the pipes connecting the two chambers of the grease trap is not a common occurrence but if this happens, any obstruction can be pushed out from the open top of the pipe extending above the liquid surface (see centre pages).

Kitchen wastewater also carries pieces of solid waste that are heavier than water. In a grease trap, these solids fall to the bottom and form a layer of settled material. It is necessary to remove this bottom layer of settled waste occasionally, otherwise the grease trap capacity will be reduced. Carefully remove and dispose of this bottom material in the same manner as for the top layer of greasy waste.

Cleaning a grease trap is not a very pleasant job and staff members responsible for this task should be encouraged to carry it out promptly as required and thoroughly.

Grease traps larger than 1000 litres can be difficult to clean well by hand. Many restaurants hire external maintenance contractors to do the job and this practice is recommended to ensure complete and proper emptying.

Some things to check if you contract out grease trap maintenance:

• Employ registered grease trap waste collector to conduct the disposal work. The most updated list of the registered collectors can be obtained from the Environmental Protection Department.
  
  
• Be sure that the cleaning frequency is adequate. The trap should still be inspected by a member of your staff between maintenance visits; cleaning should take place when the greasy waste occupies no more than the top 30% of the trap capacity.
  
  
• Obtain monthly records that will enable you to prove grease trap maintenance at a later date, if required.