What are Grease Traps?

Grease traps are devices placed on kitchen cleaning appliances such as sinks, woks, and any other drains that collect grease. Properly maintained grease traps help prevent unwanted grease build-up in
a private building’s sewer or a Boston Water and Sewer Commission sewer.

Cooking grease
that gets washed off cooking appliances and kitchenware
can end up causing significant problems in building drains and BWSC sewers. Commission regulations governing the use of sanitary and combined sewers and storm drains require properly installed and maintained grease traps in all restaurants and food establish- ments in Boston. Article 111, Section 15 states "Grease traps shall be required on sewers into which significant amounts of animal or vegetable fat, oil or grease may be discharged so that a discharge concentration does not exceed 100 milligrams per liter…the Commission shall have the right to inspect such facilities in accordance with Article VII of these regulations." For a complete copy of the regulations, please contact BWSC at (617) 989-7000.

Two Types of grease traps exist:

	Traps located in an establishment near  the fixture it serves.
	Large traps located outside the building in the ground that serve the entire kitchen.

Significant amounts of grease in buildings and BWSC sewers can come from the following fixtures:

	Pot Sinks
	Rinse Sinks at Dishwashers1
	Dishwashers Outside Trap Only2
	Woks
	Floor Drains and Sinks
	Automatic Hood Washers

These methods of cleaning are for guideline purposes only; many traps are designed differently and require specific methods for cleaning. Consult the equipment manufacturer for instructions.

	Grease traps should be cleaned when 25% of the liquid level of the trap is grease or oil, once a month minimum for point of use traps and quarterly for large in-ground interceptors.
	The cover should be removed carefully  to avoid damage to the gasket.
	Ladle off the layer of grease and oil floating on top of the water.
	Remove any baffles and scrape clean. After cleaning, the baffles can be rinsed off in the sink that flows to the trap.
	Using a strainer, scrape the bottom of the trap to remove all non-floatable food particles and debris.
	Clean the bypass vent with a flexible probe or wire.
	Reinstall baffles and cover.

Note: The grease trap should be completely emptied once a month. Many establishments have an independent contractor that specializes in grease trap cleaning perform the work.

No. Never add bleach, emulsifiers, enzymes, or any other chemical to the grease trap. These agents harm the natural bacteria that eat grease and oil in grease traps. The only additive allowed into the sewer system by BWSC is bacteria. Bacteria consume fat, 
oil and grease in the trap, turning them into water and carbon dioxide.

The food establishment’s waste hauler or renderer that removes used fryolator grease and oil normally accepts materials removed from the grease trap. Large in-ground grease traps normally hold 500 gallons or more and are usually cleaned by a contractor equipped to deal with the large quantities of grease, oil and non-floatables. It is the responsibility of the establishment owner to ensure the trap is completely cleaned.

BWSC will provide Grease Control Logs 
for the establishment owner to maintain regarding the cleaning of the Establishment’s grease traps. The log notes the date the trap is cleaned, amount of material removed, and a signature confirming the work was performed.

Proper maintenance of grease traps is essential to the smooth and sanitary operation of a food establishment.

For additional information regarding the proper maintenance and care of grease traps, 
please contact BWSC’s Discharge Enforcement Unit at (617) 989-7000.