What is a grease trap?

A grease trap is a container, generally placed underground and usually outdoors, that is required in most commercial kitchens to collect the fats, oils and greases ("FOG") that run through the drains during normal kitchen operations. Put simply, grease traps allow the FOG material to float where it can be removed, and the water to sink to bottom of the trap where it flows out of the trap into the municipal water supply. Because trap water enters the city's supply, grease traps are closely monitored and regulated by city and environmental regulations.

Grease traps are NOT intended for grease disposal - do not empty your fryer grease into a grease trap! 

Why do I need a grease trap?

Most municipalities require foodservice establishments to install a grease trap as a method of limiting the amount of greases and solids that are passed through their water treatment facilities. Businesses with commercial kitchens that produce fats, oils and grease must have an interceptor (or trap) to keep contaminates out of the city’s sewer system. Rothsay service technicians stay informed of the various municipal codes to ensure all service visits comply with current local, state and federal ordinances.

  • Grease trap diagram

How does a grease trap work?

Typically, all kitchen drains are routed through a grease trap. The trap is a holding tank that separates grease and oils from the wastewater produced from sinks, floor drains and dishwashers. Water from these sources enters a grease trap where it is separated – grease floats to the top of the trap and is removed while the wastewater exits through an outlet pipe into the city’s sewer system. There are different methods on how the trap is cleaned (full pump or pump and return, for instance), often based on city requirements or service provider capability.

How can I maintain my grease trap?

  • Have your grease trap serviced regularly by a knowledgeable service provider, such as Rothsay; this preventive maintenance will help you avoid costly backups and overflows, and the service tech can inform you of any visible damage needing repair or attention by a plumber.
  • The trap should be examined periodically for wear or damage; the gasket sealing the lid to the trap may need to be replaced if you notice smells emanating from the trap itself.
  • Educate your employees on handling grease and food waste.
  • Use drain covers in sinks to capture debris and never pour grease down the drain.
  • Scrape food off plates into trash before rinsing to avoid washing the food waste into your trap.

Can you recycle trap grease and how is it used?

While it is rare, trap grease can be recovered and recycled. The removed material is referred to as “brown grease” and is repurposed where regulations allow, most often as boiler fuel. Trap grease cannot be used for animal feed or pet food, nor can it be processed at facilities where animal feed or pet food ingredients are made. A service provider who is collecting your used cooking oil or fat and bone scraps for use in animal feed, may also service your grease trap, but separate vehicles are used, and the trap material can not be taken to the same facility where the cooking oil or meat fats are being processed. 

Most commonly, trap grease material is collected and safely disposed of in an environmentally secure manner at licensed facilities.

What size grease trap do I need?

Most important is having the right size trap for your business, and having it serviced regularly by a licensed service provider who is familiar with FOG (Fats, Oils and Greases) regulations in your city. The size of a grease trap is largely determined by the amount of grease produced by the store. In some instances, municipalities regulate the size of the grease trap and will inform you of what is needed to satisfy local requirements. On average, the typical exterior grease trap is 1,000 gallons or larger. A consultation with a  plumber or a trap manufacturer can recommend and install the right size trap for your store. Regular, professional maintenance by a licensed service provider, like Rothsay, will keep your trap running smoothly, keep you in compliance with record-keeping and disposal requirements, and alert you to problems before they become critical and costly issues.

Where can I get a grease trap?

Rothsay does not sell, provide or install grease traps; this should be done by a licensed plumber, who is familiar with all local ordinances and regulations. The size of a trap will depend on the size of your store, water usage, and grease volume. In some cases, the city will mandate what size trap should be installed. Once your trap is in place, Rothsay technicians will be happy to help you determine an efficient schedule for trap maintenance to ensure that your store stays in compliance and your trap keeps functioning. Regular maintenance will also help alert you to any problems before they become critical and costly issues.

  • Rothsay employee cleaning a grease trap

How often should I have my grease trap cleaned or serviced?

The frequency of service is determined by the volume of grease produced and the size of your trap. Reputable companies servicing grease traps can work with your business to create a service schedule compliant with applicable regulations.

How to clean a grease trap?

There are various methods on cleaning a grease trap, which may be mandated by municipal regulations. Because of this, and because of the job itself, we strongly recommend that grease trap cleaning be done by a reputable, licensed service provider who is up-to-date on any regulations that would apply to your locale. Because regulations on cleaning, record-keeping, and disposal of trap material are quite extensive, with heavy fines if not complied with, we advise store owners not do the maintenance themselves. In most cases, one DIY attempt is enough to make the most die-hard entrepreneur running for the pro the next time.  Grease trap cleaning is one of the most unpleasant, odorous, labor-intensive jobs you'll ever ask of a kitchen employee.

Methods of cleaning a trap - first, find out if your city mandates one pumping method over another. Then find a service provider capable of providing the mandated, or your preferred, type of service.

Pump and return - the fats, oils and greases (FOG material) are removed and taken away with the service provider, but the separated gray water (i.e., the water left after grease is removed) is returned to your grease trap. This is a preferred method. but not all providers offer it as it requires specialized vehicles.

Dry pump - your service provider removes the entire contents of the trap, hauling away the FOG with the gray water, leaving your trap dry until it starts to fill again (a dry tank can emit strong odors until water is again introduced)

It is important to know that YOU are responsible for the material removed from your trap, even after it is carted off your property.  If your service provider is illegally dumping the material in a stream or other unauthorized location, you can be fined. Be sure you partner with someone you can trust to handle the job responsibly and in full compliance with all applicable regulations. Records should be kept and available for municipal inspections.

Is it ok to put grease down the drain? Isn’t that what the grease trap is for?

Grease should never be poured down a drain, as it will solidify while traveling through the pipe and can cause clogging, backups and overflows. Such blockages can not only damage your plumbing system, but it can also cause issues with local city sewage systems… and result in fines for the business owner. Grease traps are intended to capture residual grease and are not meant for the disposal of solid materials.

The grease trap company said I’m responsible for my grease from cradle-to-grave. What does that mean?

Store owners are responsible for their grease and ensuring material in their grease traps that cannot be recycled is disposed of in an environmentally sound manner. If a non-reputable service provider cleans your traps and dumps the removed material illegally, you can be held liable for that violation. Make sure you are working with a reputable company, such as Rothsay, to ensure you are complying with all ordinances.

What are the fines if my grease trap overflows?

While the amount of the fine is generally determined at the municipal level, several factors are taken into consideration, such as the number of previous overflows, if grease trap services have been regularly maintained, and if trap samples exceed fat, oil and grease (FOG) limits. FOG regulations can vary by municipality, county and/or state. Your service provider should be familiar with local FOG requirements so they can ensure your traps are being serviced, and trap material is being disposed of, in compliance with city regulations.

My grease trap overflowed. Can you help?

Many overflows may require the assistance of a plumber to clear any blockages. We are more than happy to remove the contents of the trap, but if a clog is the source of the overflow, a plumber will need to address the issue for the grease trap to function properly.  With regularly scheduled maintenance, clogs and disruptions can be avoided.

Why does my restaurant smell after I just had my trap cleaned?

There may be several causes for the smell.

  • A worn or corroded gasket around the manhole cover may allow gases from your grease trap to escape and drift into your restaurant.
  • There could be a backup in the line to the trap, caused by grease and food clogs; you will need to call a plumber to clear any clogs.
  • If the smell occurs right after a trap service visit, it could be associated with the method used to clean your grease trap and will soon dissipate. Our DAR PRO Solutions brand has a blog article describing more about the causes and solutions for smelly traps.

I have a grease interceptor. Do I need a grease trap?

A grease interceptor is commonly referred to as a grease trap. Both terms are referencing the same thing.

Do you repair grease traps?

This is not a service currently offered by Rothsay; however, we do monitor your grease trap during service visits. As part of our consulting process, we will analyze the condition of your trap and make recommendations, should repairs be needed. Regular grease trap maintenance will help keep your trap running smoothly and reduce repairs and emergency calls to a plumber.