3-Compartment Sink Plumbing Estimator
A commercial three-compartment sink (wash, rinse, sanitize) is core food-service plumbing, and it is plumbed very differently from a home kitchen sink. Each basin drains through an indirect waste connection with an air gap over a floor sink, so a drain stoppage can never back up into a food-contact basin. Food service also needs a separate dedicated handwash sink nearby - the 3-comp basins are not for handwashing. If the sink handles greasy pots and pans, its waste typically has to route to a grease interceptor. Cost drivers are the sink configuration (standard, with drainboards, oversized/4-comp, or multiple sinks), hot-water and supply needs, whether you tie into existing plumbing or run new supply and indirect waste, and add-ons like a floor sink, grease tie-in, or handwash sink.
A three-compartment sink exists to manually wash, rinse, and sanitize ware in three separate basins - the standard method where there is no commercial dishwasher (or as a backup to one). The basins, drainboards, and faucet are sized for the volume of pots, pans, and utensils a kitchen produces.
Why It Matters
Because the basins hold food-contact items, the plumbing has to protect them. That means an indirect, air-gapped drain and a separate handwash sink - the 3-comp sink is not a handwashing fixture and is not a mop sink. Getting the fixture mix right is part of passing health review.
Each compartment's drain discharges indirectly - through an air gap or air break over a floor sink or indirect-waste receptor - rather than being hard-piped into the sanitary line. The visible vertical gap between the sink tailpiece/drain and the receptor is what keeps a sewer backup out of the basins.
FL Notes
Many Florida kitchens already have a floor sink near the warewashing area; if not, adding one is part of the job. Indirect-waste and air-gap rules follow the adopted plumbing code and the health authority - verify the receptor location, the size of the air gap, and venting for your layout.
Food service requires a dedicated handwash sink in or adjacent to food-prep and warewashing areas, separate from the 3-comp sink and from any prep sink. It needs hot and cold water at a usable temperature, plus soap and towels at the fixture.
Plan for It
If a handwash sink is missing or in the wrong spot, expect to add or relocate one - it is a common health-inspection item. We size the supply, drain (often indirect to the same floor sink), and faucet so it is convenient enough that staff actually use it.
Washing greasy pots and pans sends fats, oils, and grease (FOG) down the drain. Depending on the operation and the local utility's FOG program, the 3-comp sink's waste may have to pass through a grease interceptor (under-sink unit or larger in-ground interceptor) before the sanitary sewer.
FL Notes
Florida utilities run FOG / pretreatment programs and many require interceptors on warewashing fixtures. Whether your sink ties to an existing interceptor, needs a new one, or is exempt depends on the utility and the AHJ - confirm before you plumb so the waste routing and sizing are right.
The sanitize step needs adequate hot water; some operations use a booster or point-of-use heater for the warewashing area, plus a commercial faucet and sometimes a pre-rinse spray valve. Much of Florida's water is hard, leaving scale on fixtures and spray valves.
Plan for It
We confirm the hot-water source and demand for the sink, set the faucet/spray, and where hard water is an issue add appropriate filtration so spray valves and aerators do not clog. Sanitizing method (hot water vs chemical) follows the health authority.
Best Time: With the Kitchen Build-Out
Roughing in supply, the floor sink, and indirect waste while the kitchen is being built or remodeled is far cleaner than retrofitting around finished equipment and a tile floor.
Typical Install
1. Confirm fixture layout, sink size, and the health-required handwash sink. 2. Run hot & cold supply with backflow protection as required. 3. Provide a floor sink / indirect-waste receptor. 4. Drain each basin indirectly with an air gap. 5. Route greasy waste to a grease interceptor where required. 6. Set the faucet / pre-rinse and any booster heat. 7. Test for drainage, leaks, and proper air gaps.
FL Gotchas
Hard-piping a basin to the sewer (no air gap), using the 3-comp sink as the handwash sink, skipping a required interceptor, undersized hot water, and long flat drain runs that clog.
Warewashing plumbing gets heavy daily use, so upkeep keeps it draining and inspection-ready in Florida kitchens.
Routine Care
Keep the air gaps and floor sink clear, watch for slow basins, service the grease interceptor on schedule, clean spray-valve and faucet aerators (more often on hard FL water), and keep the handwash sink stocked and working.
Warning Signs
Standing water in a basin or floor sink, a sewer smell, grease backing up, a dripping pre-rinse, or a handwash sink that is cold or out of service all point to service - and several are direct inspection findings.
The sink fixture itself is separate - this is the plumbing: supply, indirect waste, and grease routing drive the total. These are planning estimates for the work plus professional labor in the FL market.
Configuration & Scope
Tying a standard 3-comp sink into nearby supply and an existing floor sink is the low end; a full build-out with new supply, a new floor sink, a separate handwash sink, and a grease-interceptor tie-in is the high end.
Add-ons
A dedicated floor sink / air-gap receptor, a grease interceptor tie-in, a separate handwash sink, and indirect waste for adjacent equipment each add. Use the calculator to combine configuration, hot-water/supply, scope, and add-ons.
FL Permit Requirements
- Replacing a 3-comp sink that is already correctly plumbed, like-for-like
- Swapping a faucet or pre-rinse spray valve
- Re-establishing an air gap on an existing indirect drain (verify locally)
- New supply runs and indirect waste / a new floor sink
- Adding or relocating the required handwash sink
- Tying warewashing waste into a new or existing grease interceptor
- Backflow / cross-connection protection on the supply
FL County Permit Fee Reference
Replacing a like-plumbed sink or a faucet is usually minor. New supply and indirect waste, a new floor sink, a handwash sink, or grease-interceptor work is regulated and often permitted, and commercial kitchens typically also involve health-department and plan review. Fees and timelines are approximate — verify with your local building department / AHJ (and health department) before starting work.
| County | Permit Fee | Est. Processing |
|---|
FL Code References
Who Can Pull a Permit in FL?
Plumbing a commercial three-compartment sink - hot and cold supply, an indirect (air-gapped) drain for each basin to a floor sink, a separate handwash sink, and grease routing where required - is regulated plumbing work that generally requires a permit, and because it is food-service warewashing it also intersects with health-department review for indirect waste, air gaps, and the required fixtures. Supply sizing, indirect-waste and air-gap rules, backflow / cross-connection protection, and grease-interceptor requirements follow the adopted Florida Building Code (Plumbing), the FOG / pretreatment program of the local utility, local amendments, and the AHJ, and new commercial work is permitted and inspected. A like-for-like sink swap or faucet change is usually minor. Per FL Statute 489.105, regulated plumbing and related construction work is performed by the appropriate licensed contractor.
Verify any contractor's license at myfloridalicense.com and confirm requirements with your local building department before work begins.
Get a Free 3-Compartment Sink Plumbing Estimate
Licensed FL Contractor - Commercial Sink Supply, Indirect Waste & Grease Routing
We plumb three-compartment sinks for restaurants, bars, food trucks, schools, and commercial kitchens — standard, drainboard, oversized/4-comp, and multi-sink setups — with hot & cold supply, an indirect drain to a floor sink through a proper air gap, the separate handwash sink food service needs, and grease-interceptor routing where the utility requires it.