Fat-Free Sewers

How to Prevent Fats, Oils, and Greases from Damaging Your Home and the Environment
Fats, Oils, and Greases aren't just bad for your arteries and your waistline; they're bad for sewers, too.

Sewer overflows and backups can cause health hazards, damage home interiors, and threaten the environment. An increasingly common cause of overflows is sewer pipes blocked by grease. Grease gets into the sewer from household drains as well as from poorly maintained grease traps in restaurants and other businesses.

Where does the grease come from?

Most of us know grease as the byproduct of cooking. Grease is found in such things as:

  • Meat fats
  • Lard
  • Cooking oil
  • Shortening
  • Butter and Margarine
  • Food scraps
  • Baking Goods
  • Sauces
  • Dairy products

Too often, grease is washed into the plumbing system, usually through the kitchen sink. Grease sticks to the insides of sewer pipes (both on your property and in the streets). Over time, the grease can build up and block the entire pipe.

Home garbage disposals do not keep grease out of the plumbing system. These units only shred solid material into smaller pieces and do not prevent grease from going down the drain. Commercial additives, including detergents, that claim to dissolve grease may pass grease down the line and cause problems in other areas.

The results can be:

  • Raw sewage overflowing in your home or your neighbor's home;
  • An expensive and unpleasant cleanup that often must be paid for by you, the homeowner;
  • Raw sewage overflowing into parks, yards, and streets;
  • Potential contact with disease-causing organisms; and
  • An increase in operation and maintenance costs for local sewer departments, which causes higher sewer bills for customers.

What can we do to help?

The easiest way to solve the grease problem and help prevent overflows of raw sewage is to keep this material out of the sewer system in the first place.

There are several ways to do this:

  • Never pour grease down sink drains or into toilets.
  • Scrape grease and food scraps from trays, plates, pots, pans, utensils, and grills and cooking surfaces into a can or the trash for disposal (or recycling where available).
  • Do not put grease down garbage disposals. Put baskets/strainers in sink drains to catch food scraps and other solids, and empty the drain baskets/strainers into the trash for disposal.
  • Speak with your friends and neighbors about the problem of grease in the sewer system and how to keep it out. Call your local sewer system authority if you have any questions.

What restaurant and building owners need to know about grease traps or interceptors.

Restaurants, large buildings (such as apartment complexes), and other commercial establishments may have grease traps or interceptors that keep grease out of the sewer system. For a grease trap or interceptor to work correctly, it must be properly.

  • Designed (sized and manufactured to handle the amount that is expected),
  • Installed (level, vented, etc.), and
  • Maintained (cleaned and serviced on a frequent basis).

Solids should never be put into grease traps or interceptors. Routine, often daily, maintenance of grease traps and interceptors is needed to ensure that they properly reduce or prevent blockages.

Be cautious of chemicals and additives (including soaps and detergents) that claim to dissolve grease. Some of these additives simply pass grease down pipes where it can clog the sewer lines in another area.

This brochure was prepared under Cooperative Agreement Assistance #CX824505-01-0 between the Water Environment Federation (WEF) and the U.S. Environmental Protection Agency.

Please visit the Water Environment Federation (WEF) website at www.wef.org for more information.

Frequently Asked Questions

If you are not sure whether you have a grease trap or not, please contact a local plumber for assistance.
The Town of Jamestown requires installation of a grease handling device if your wastewater contains grease, oils, fats, sediments, particular matter, or any other material that can impair the flow of the wastewater through the wastewater collection system.
An interceptor is a device connected to your plumbing system, designed to remove oil and grease from the wastewater before it enters the Town's wastewater collection system. It is a big concrete box portioned off to remove grease and food waste by trapping things that float and things that settle to the bottom. Interceptors are installed in the ground outside a food service establishment. A grease trap is a smaller unit, often stainless steel, which works by the same principles. Grease traps are installed indoors, often under a counter.
The proper pumping and cleaning frequency is dependent upon many variables, including but not limited to, type of food prepared, cooking and cleaning methods, volume of food or meals prepared, and the size of your grease interceptor. The Town requires that all grease interceptors be pumped and cleaned out at least every 90 days and grease traps daily.
To effectively remove oil and grease, a grease interceptor must retain the water long enough for the oil and grease to separate and float or rise to the baffle chamber. The period of time the water is detained in the unit is called the detention time. The Town of Jamestown requires that grease interceptors provide a minimum of 20 minutes hydraulic detention time between the influent and effluent baffles with 20 percent of the total volume of the grease interceptor being allowed for sludge pocket.
Oil and Grease in the wastewater system builds up on the walls of the sewer lines, accumulates in pump station wet wells and clogs pumping and control equipment. When oil and grease build up on the walls of the sewer line it reduces the system's capacity and can result in complete blockage. This blockage results in sewer backups and overflows, greatly increased man hours and maintenance costs, and equipment downtime.
No, any establishment that does not have a properly sized and properly maintained grease interceptor is in violation of this Policy and Town Code of Ordinance.
Absolutely, the ground up solids that go through the disposal will settle to the bottom of the grease interceptor and take up valuable space. The reduced volume will lower the detention time of the devise and will reduce its efficiency. The increase loading will also lead to increased maintenance frequency and cost.
It is possible to permit the installation of interior under-the-counter interceptors instead of exterior in-ground interceptors in instances of space limitations. However, this installation will require increased maintenance and implementation of best management practices to offset trap inefficiency. The automatic grease removal systems are another possible alternative.
Most plumbers and plumbing contractors install grease interceptors. All Grease interceptors must be permitted by the Town and Guilford County prior to installation.