In most commercial kitchens, yes: a three compartment sink used for washing pots, pans and dishes normally has to drain through a grease trap or grease interceptor. The requirement does not come from the sink itself. It comes from your plumbing code and your local sewer authority, and the details change from one town to the next.
Shop the equipment in this article: hand sink, Compartment sinks and Grease traps. Freight is included on every order.
Where the rule comes from
The FDA Food Code tells you that you need a warewashing sink. It does not decide whether that sink needs grease protection. That part belongs to the plumbing code your state or city has adopted, plus the sewer use rules of whoever treats your wastewater.
Most of the country uses one of two model plumbing codes, usually with local amendments:
- International Plumbing Code, section 1003.3.1. A grease interceptor or automatic grease removal device is required to receive drainage from fixtures and equipment with grease-laden waste in food preparation areas such as restaurants. The listed fixtures include pot sinks and prerinse sinks.
- Uniform Plumbing Code, section 1014.1. Where the authority having jurisdiction determines that pretreatment is required, an approved grease interceptor must receive drainage from fixtures or equipment that produce grease-laden waste. The section names restaurants, cafes, lunch counters, cafeterias, bars and clubs among the establishments covered.
A three compartment sink where greasy cookware is washed is a pot sink in every practical sense, so under either code it is one of the first fixtures a plan reviewer will expect to see connected.
Where local rules differ
Sewer authorities write their own fats, oils and grease rules. Federal pretreatment regulations prohibit sending solid or viscous pollutants into a public sewer in amounts that cause obstruction (40 CFR 403.5(b)(3)), and local programs enforce that through their own ordinances. That is why two neighboring cities can give different answers. Common differences include:
- Which fixtures must connect. Some cities add mop sinks, prep sinks and floor drains to the list. Others require every kitchen fixture except the hand sink.
- Dishwashers. The International Plumbing Code list includes dishwashers that do not have prerinse sinks. The Uniform Plumbing Code, section 1014.1.3, says a dishwasher may not discharge into a grease interceptor. Local amendments go both ways.
- Type and location of the device. Some authorities accept a small unit under or beside the sink. Others require a large in-ground interceptor outside the building, especially for full kitchens.
- Sizing. The size is calculated from your fixtures using the method your local code specifies. Do not guess, and do not buy a unit before the size is approved.
Common problems
- Buying the trap first. Owners often order a unit, then learn the sewer district wants a different size or type.
- Forgetting the indirect drain. Food Code section 5-402.11 prohibits a direct connection between the sewage system and a drain from equipment in which food, portable equipment or utensils are placed. It allows a direct connection for a warewashing sink only where the law allows it. Many jurisdictions still want the sink to drain through an air gap, so ask how yours wants the sink, the trap and the floor sink arranged.
- Skipping maintenance. The Uniform Plumbing Code, section 1014.1.2, requires interceptors to be kept in efficient operating condition by periodic removal of accumulated grease. Local programs usually set the cleaning schedule and ask for records.
- Assuming a takeover space is covered. An existing trap may not meet current rules once you remodel or change the menu.
Your local plumbing department or sewer authority has the final say on grease traps, and your local health department has the final say on the sink, so confirm with both before you buy.
What to buy
Settle the plumbing answer first, then order the equipment to match it.
- Compartment sinks with bowls large enough to immerse your biggest pot or pan. Express KitchQuip’s own stainless steel sinks are NSF certified.
- Grease traps in the size and type your plumbing or sewer authority approves in writing.
- Faucets that reach every bowl.
- Dishtables if you need soiled and clean landing space beside the sink.
Freight to the 48 contiguous states is included in the price.