Food truck greywater disposal comes down to one rule with a few moving parts: capture all the used water from your sinks in an onboard holding tank that meets FDA Food Code sizing, then empty it only at an approved site connected to a sanitary sewer. That usually means a commissary dump station, a municipal or commercial interceptor site, or a licensed sewage transport service. Dump it anywhere else and you are exposed to Clean Water Act penalties that start at $2,500 per day on top of local health and sewer enforcement.
What Counts as Greywater
Greywater on a mobile food unit is the used water draining from your handwashing sink, your three-compartment warewashing station, and any food prep surfaces. It carries soap, food particles, and grease. It is not blackwater, which comes from toilets, and most food trucks don’t have those.
The distinction matters less than operators sometimes assume. The FDA Food Code treats all liquid waste from a mobile food establishment as sewage for disposal purposes, so it has to be routed to an approved treatment system regardless of what went into it. Greywater can still carry bacteria, chemical residue, and concentrations of fats, oils, and grease beyond what local sewer systems are built to handle.
Tank Size and Construction
FDA Food Code Section 5-401.11 sets two specific requirements for the sewage holding tank on your unit. The tank must be sized at least 15 percent larger in capacity than the fresh water supply tank, which gives you headroom for food debris, grease, and the water already in the system when you start the day. It must also slope to a drain with an inner diameter of at least one inch and be fitted with a shut-off valve.1U.S. Food and Drug Administration. FDA Food Code 2022 Full Document
The slope is not cosmetic. Without it, sludge collects in flat spots, bacteria multiply in the standing liquid, and the tank produces the kind of odors that get a unit flagged at inspection. Most manufacturers build these tanks from high-density polyethylene or similar non-corrosive, smooth-walled material that resists buildup and cleans easily. The waste drain is deliberately larger than the fresh water fill hose so the two connections can’t be swapped by mistake.1U.S. Food and Drug Administration. FDA Food Code 2022 Full Document
Where You Can Legally Dump It
Food Code Section 5-402.14 requires that sewage and other liquid waste from a mobile food unit be removed at an approved waste servicing area or by a sewage transport vehicle, without creating a public health hazard. Section 5-403.11 adds that the waste must ultimately reach either a public sewage treatment plant or an approved individual sewage disposal system.1U.S. Food and Drug Administration. FDA Food Code 2022 Full Document
In practice, operators use one of three options:
- A licensed commissary with a designated dump station connected to the sanitary sewer. This is the most common arrangement, and many health departments won’t issue or renew a mobile food permit without a signed commissary agreement on file.
- A municipal dump station or an approved commercial interceptor site. Some charge per visit, others sell annual access.
- A licensed sewage transport service that comes to your location and pumps the tank into a transport vehicle. Costs more, but works for operators who park nowhere near a commissary.
Whichever route you use, most jurisdictions require a signed service agreement or disposal permit documenting where your waste goes. Health inspectors check for this on routine visits, and not having one on hand is a reliable way to lose a day of service. When you first approach a disposal facility, expect to show vehicle identification, an estimate of your daily waste volume, your health permit, and your business license.
How to Empty the Tank
Section 5-402.15 requires that the waste retention tank be thoroughly flushed and drained in a sanitary manner during every servicing operation.1U.S. Food and Drug Administration. FDA Food Code 2022 Full Document The process is simple, but a sloppy dump can draw a violation even at an approved site.
Park on a level surface next to the intake valve. Attach a heavy-duty hose to the discharge fitting on the waste tank and secure the other end to the disposal inlet. Check both connections before opening the shut-off valve. Gravity handles the rest on a properly sloped tank. Once empty, flush the interior with clean water to clear residual grease and particles, then drain that rinse through the same connection. Close the valve, disconnect, flush the hose, and replace the tank cap before pulling away.
Skip the rinse and deposits build up between dumps. Over a few months, that is how operators discover their effective tank capacity has mysteriously shrunk.
Keeping a Disposal Log
A disposal log is your proof that waste went where it was supposed to go. Most local health codes require one, and inspectors look at it during renewals and spot checks. Each entry should list the date and time of the dump, the name and address of the disposal facility, and the approximate volume emptied. If you dump at a supervised commissary, get the facility manager’s signature on the entry.
Retention periods vary. Keeping records on the vehicle for at least 90 days is a common minimum; some jurisdictions require up to a year, and a full year is the safer habit either way. A missing or incomplete logbook is one of the easiest violations for an inspector to write, and it tends to invite closer scrutiny of everything else on the truck.
Backflow Prevention and Cross-Connections
The fastest way to contaminate your fresh water is a backflow event, where dirty water gets siphoned backward into clean lines. Food Code Section 5-202.13 requires an air gap between any water supply inlet and the flood level rim of a plumbing fixture, at least twice the diameter of the inlet and never less than one inch.1U.S. Food and Drug Administration. FDA Food Code 2022 Full Document You should see visible open air between the end of the water line and the sink basin. If they are touching or submerged, you have a cross-connection.
Section 5-402.11 adds a second layer, prohibiting any direct connection between the sewage system and a drain originating from equipment where food, portable equipment, or utensils are placed.1U.S. Food and Drug Administration. FDA Food Code 2022 Full Document Your warewashing sink should drain through an indirect connection, not pipe straight into the waste tank. Many local health departments also require a mechanical backflow device, such as an atmospheric vacuum breaker or a pressure vacuum breaker. The local permitting office specifies the device during plan review.
Grease Traps
If your menu produces significant grease, you will likely need a trap. Food Code Section 5-402.12 says only that, if used, a grease trap must sit where it is easily accessible for cleaning.1U.S. Food and Drug Administration. FDA Food Code 2022 Full Document The real specifics come from local sewer ordinances.
A widely adopted standard is the 25-percent rule: when the combined depth of the floating grease layer and settled sludge reaches 25 percent of the trap’s total liquid depth, the trap needs to be pumped. Past that threshold, grease passes through into the sewer and triggers violations from the local sewer authority. Many jurisdictions require monthly operator inspections and professional pumping at least quarterly, or sooner if the trap hits 25 percent. On mobile units, the trap is typically a small under-sink unit rather than the in-ground interceptor a brick-and-mortar restaurant uses, and undersized traps are among the most common violations inspectors cite on food trucks.
Penalties for Illegal Dumping
Dumping greywater into a storm drain, a parking lot, a gutter, or any surface not connected to an approved sanitary sewer violates federal, state, and local law. Storm drains flow directly to rivers, lakes, and coastal waters without treatment, so even mild food-service wastewater becomes contamination the moment it enters the system.
At the federal level, the Clean Water Act makes it unlawful to discharge pollutants into waters of the United States without a permit. A negligent violation carries fines of $2,500 to $25,000 per day plus up to one year of imprisonment. A knowing violation runs $5,000 to $50,000 per day and up to three years. Repeat offenders face doubled maximums.2Office of the Law Revision Counsel. 33 USC 1319 – Enforcement
Local penalties stack on top. Health departments in most jurisdictions can suspend a mobile food permit immediately after discovering illegal dumping, and reinstatement usually requires re-inspection fees and a corrected disposal plan. The local sewer authority may impose separate fines for unpermitted discharge. A single incident in a parking lot can set off simultaneous enforcement from the health department, the local environmental agency, and the sewer utility. Measured against the cost of a commissary agreement, the financial risk of cutting the corner is out of all proportion to the saving.