How to Design Drainage for a Commercial Kitchen

A kitchen has special technical needs. Design must follow the relevant codes and still adapt to site conditions, with safety, reliability, and practical performance as the targets. CHINENG summarizes the guiding principles for kitchen water supply and drainage design.

(1) Finalize the kitchen scheme early and coordinate the trades. Flow rates, outlets, and pipe routes must follow the equipment layout. Owners should state requirements early so the layout can be completed and the drainage design can follow. The same applies to fit-outs: most small and mid-size restaurants reuse existing rooms, and the installed services are often inadequate. Capacity upgrades need early technical input. Late equipment layout leads to redesign and rework.

(2) Use professional design

Fit-out projects often lack matching infrastructure. In any kitchen of real size, rule-of-thumb work leaves gaps—especially in flow and pipe sizing. Have specialists calculate and design once, correctly. On new builds, kitchen layout should also be done early by specialists and signed off by kitchen managers so the architectural team has a solid basis.

(3) Detail every point

Drainage design must match equipment outlets and clear other services. Detail to national and local rules, mark every point with technical notes, and make construction straightforward. Examples: drain slope, interceptor depth, and inlet/outlet heights must be calculated from the municipal invert and the finished floor, with the drain route planned carefully.

(4) Practical reliability

Besides following the codes, raise materials and design standards where the duty is harsh, without wasting cost. A normal sink may use DN50 plastic waste, but kitchen wastewater carries grease and grit. Hot flushing of grease-laden lines calls for thicker, heat-resistant DN75 pipe to reduce blockage.

(5) Leave spare capacity

Once the building services are fixed, adding flow or moving pipes is hard. Markets change and kitchens may alter process or add equipment; neighboring uses may also compete for water. Design with margin—spare flow and spare outlets that can serve as wash points in normal operation.

(6) Easy inspection and maintenance

Codes require access for inspection. Commercial kitchens are crowded, and drains clog easily, so reliable maintenance access is mandatory. Provide cleanouts at bends and where pipes cross into other spaces, and keep horizontal runs as short as possible.

(7) Human-centered placement

Designers must understand kitchen workflow. Place sinks where staff actually need them so daily work stays convenient for years.

(8) Complete functions

Include open channels, interceptors, odor traps, and pest-proofing of pipe penetrations. Missing functions are hard to add after construction.

(9) Follow local rules

National and regional kitchen rules, plus building inspection, environmental, and hygiene requirements, all apply. Design to those rules and submit early for review and acceptance.

In summary: these are CHINENG’s notes on commercial kitchen drainage design. Follow the CHINENG website for ongoing updates.