Grease Traps, Hand Sinks and Floor Drains: Food-Service Plumbing in New Jersey
Key takeaways
- Grease interceptor size and location are decided by your equipment schedule and by the local sewer authority, not by what fits under the sink.
- Hand sink count and placement is one of the most common plan review corrections in food-service projects.
- Food equipment drains indirectly through an air gap, not by hard piping into the waste line. This catches almost every first-time operator.
- Health department plan review and municipal plumbing permits are two separate approvals and both happen before construction.
In a restaurant build-out, the plumbing under the floor and behind the wall decides whether you open on time. Not the finishes, not the signage. We have watched beautifully built kitchens sit closed for weeks because a hand sink was in the wrong place or an interceptor was undersized for the equipment that actually got installed.
This is the working version of what we check on food-service projects across Middlesex County and the surrounding area. Requirements come from the plumbing sub-code, from the state retail food rules enforced by your local health authority, and from the sewer authority that receives your discharge. All three have a say, and they do not always say the same thing, which is why this gets settled on drawings rather than on site.
The grease interceptor
Anything that produces fats, oils and grease has to be intercepted before it reaches the sewer. That covers the three-compartment sink, the pot sink, the pre-rinse, the wok range, the dishwasher in many cases, and floor drains under cooking equipment.
Two broad approaches exist and the choice is usually made for you.
| Type | Where it goes | Considerations |
|---|---|---|
| Hydromechanical, sometimes called a grease trap | Indoors, under a sink or recessed in the floor near the fixtures | Smaller and cheaper, needs frequent cleaning, sized by flow rate from the fixtures it serves |
| Gravity interceptor, in-ground | Outside the building, in the ground, pumped on a schedule | Large capacity, longer service intervals, needs space, access for a pump truck and often the landlord's consent |
Sizing comes from the fixtures and equipment connected to it, using the method your local authority accepts. What matters practically is this: the size is derived from your equipment schedule. If you add a fryer or a second pot sink after the interceptor is specified, the sizing changes. This is one of several reasons we ask operators to lock the equipment list before the plumbing drawings go out.
Plan for maintenance as well as installation. Interceptors need cleaning on a schedule, records are commonly required to be kept on site, and a neglected trap is both a health inspection issue and a backup waiting to happen in the middle of service.
Hand sinks: the most corrected item in plan review
Dedicated hand washing sinks are separate from the food prep sink, the three-compartment sink and the mop sink. They cannot be used for anything else, and they have to be genuinely accessible from where people are working, not behind a rack or around a corner.
- One in the food preparation area, positioned so staff can reach it without walking past other work.
- One in or immediately adjacent to the warewashing area.
- One in each restroom, which is a separate requirement to the kitchen sinks.
- Hot and cold water through a mixing valve, with the water reaching the temperature your health authority requires.
- Soap dispenser, single-use towels or an approved drying device, and a waste receptacle at each sink.
- A splash guard where the sink sits close to a food contact surface or a prep table.
The number required depends on the layout and the size of the operation, and the health authority reviewing your plan makes that call. Draw them early. Adding a hand sink after the walls are tiled and the slab is patched is one of the more expensive small items in construction.
Indirect waste and air gaps
This is the concept that trips up nearly every operator on a first build. Equipment that holds or touches food generally cannot be hard piped into the sanitary waste line. It has to discharge indirectly, through an air gap, into a floor sink or a receptor open to the air, so that a backup in the drain line can never siphon back into food equipment.
Equipment that typically drains indirectly includes:
- Ice machines and ice bins.
- The three-compartment sink and prep sinks, depending on the local interpretation.
- Walk-in and reach-in refrigeration condensate.
- Steam tables, steamers, kettles and combi ovens.
- Soda and beverage dispensing equipment.
- Dipper wells and drainboards.
The practical consequence is floor sinks, and floor sinks have to be located under or next to the equipment they serve. That means their positions come off the equipment plan and get cast into the slab. Move a piece of equipment three feet after the concrete is poured and you are cutting the floor.
Floor drains, floor sinks and the mop sink
| Fixture | Purpose | Placement notes |
|---|---|---|
| Floor sink | Receives indirect waste through an air gap | Under or adjacent to the equipment it serves. Must stay accessible and cleanable. |
| Floor drain | Receives wash-down water in cooking and warewashing areas | Floor slopes to it. Trap primer needed so the trap does not dry out and let sewer gas in. |
| Mop or service sink | Filling and emptying mop buckets | Required in most food establishments, and it must not be the hand sink or a prep sink |
| Grease-side floor drains | Drains beneath cooking equipment | Route to the interceptor, not straight to sewer |
Trap primers deserve a mention because they are cheap, invisible and constantly omitted. A floor drain whose trap dries out becomes an open pipe to the sewer, and the smell arrives long before the inspector does.
Backflow protection and water supply
Anywhere the potable water supply could be contaminated by what is on the other side of the connection, backflow protection is required. In a commercial kitchen that typically covers the mop sink hose connection, carbonated beverage equipment, dishwashers, the boiler or hot water make-up connection and any hose bibs.
Hot water capacity is the other supply-side item worth checking early. A three-compartment sink, a dishwasher with a sanitizing cycle and multiple hand sinks running at once is a real demand, and undersizing the water heater shows up as a failed inspection or an unhappy dish pit, not as a plumbing problem you can see.
Two approvals, running in parallel
Food-service plumbing in New Jersey has to satisfy two separate reviewers, and they are not the same office.
- 1The municipal construction office, under the plumbing sub-code of the Uniform Construction Code. This is the permit, the rough inspection and the final inspection.
- 2The local health authority, which reviews the plan for a retail food establishment before construction and inspects the finished space before you can serve customers. Fixture counts, finishes, sink placement and equipment layout are all in scope here.
Requirements vary between towns and authorities, so treat this article as orientation and have your contractor confirm specifics with the local construction office, the health authority and the sewer authority before the drawings are finalized.
“Every expensive plumbing mistake we see in a restaurant was a five minute decision that nobody made at drawing stage.”
A short pre-construction checklist
- Equipment schedule finalized, with cut sheets, before plumbing drawings are issued.
- Interceptor type and size confirmed with the sewer authority in writing.
- Hand sink count and locations confirmed with the health authority at plan review.
- Floor sink and floor drain locations laid out against the equipment plan, not the architectural plan.
- Hot water demand calculated against the actual fixture list.
- Backflow devices identified for every connection that needs one.
- Access confirmed for interceptor cleaning, including the route a service truck will take.
Empire Assemble builds restaurant and food-service fit-outs across New Jersey and Staten Island with plumbing, electrical, millwork, framing and finishes under one contract. We are licensed and insured. If you are pricing a space or reviewing a set of drawings, send it over and we will tell you what the plumbing scope really involves.
Frequently asked questions
Do I need a grease trap for my restaurant in New Jersey?
If your operation produces fats, oils or grease, then yes, some form of grease interception is required before discharge to the sewer. The type and size depend on the fixtures and equipment connected to it and on the requirements of your local sewer authority, which can exceed the plumbing code minimum. Confirm those requirements at drawing stage rather than after the slab is cut.
How many hand sinks does a commercial kitchen need?
It depends on layout and operation size, and your local health authority decides during plan review. In practice, expect at least one in the food preparation area, one in or beside the warewashing area, and one in each restroom, each with hot and cold water, soap, single-use towels and a waste receptacle. Hand sinks cannot double as prep sinks or mop sinks.
What is an indirect waste connection?
It means the equipment discharges through an air gap into an open floor sink or receptor rather than being hard piped into the sanitary waste line, so a sewer backup can never reach food equipment. Ice machines, refrigeration condensate, steam equipment and beverage dispensers are typical examples. It is the reason floor sink locations have to be set from the equipment plan before the slab is poured.
Who inspects restaurant plumbing in New Jersey?
Two separate authorities. The municipal construction office inspects the work under the plumbing sub-code at rough-in and completion. The local health authority reviews the plan for a retail food establishment before construction and inspects the finished space before you can open. Both approvals are needed and they run on separate schedules.
How often does a grease interceptor need cleaning?
It depends on the size of the unit and the volume of grease your operation produces. Indoor hydromechanical units generally need service far more often than large in-ground gravity interceptors. Local authorities frequently require cleaning records to be kept on site, so set the schedule up as part of opening rather than waiting for the first inspection to ask about it.