Are enzyme or grease-dissolving drain treatments allowed for Phoenix restaurants?

The rule exists because these products do not actually remove grease. They change its form for a short time. An enzyme, bacteria, emulsifier, or solvent product breaks the grease into smaller droplets or liquefies it so it flows out of your interceptor instead of floating and getting trapped the way the interceptor is designed to make it. That looks like a clean trap on the day you use it.

The grease does not disappear, though. Once it leaves your interceptor and moves into the cooler city sewer main, it cools off. Then it re-congeals and sticks to the pipe walls downstream. So the product just moves your grease problem from a tank you control to a public main you do not. The City of Phoenix FOG Best Management Practices are part of the program under Phoenix City Code Chapter 28. They treat the use of enzymes, bacteria, solvents, or emulsifiers to pass grease through an interceptor as a prohibited practice, for exactly this reason.

This matters more in a sewer system than in a single home drain. A grease interceptor exists to hold grease back. The goal is to keep it from ever reaching the public sewer. A product that defeats that hold defeats the whole point of the interceptor, even if the tank looks empty afterward. The grease is still there. It is just farther down the pipe, where you cannot see it or reach it.

Grease is the single largest cause of sewer blockages, and the data is not close. The EPA Report to Congress on combined and sanitary sewer overflows found that grease accounted for 47% of reported sewer blockages, more than tree roots (22%) or general debris. The EPA report puts it plainly:

"Grease was reported as the cause for 47 percent of the reported sewer blockages."

Those blockages are the leading cause of sanitary sewer overflows (SSOs), which are releases of raw sewage from the collection system into streets, yards, businesses, and waterways. The EPA estimates there are roughly 23,000 to 75,000 SSO events in the United States each year. When you "dissolve" grease past your interceptor, you are feeding the exact material that drives nearly half of these failures into the shared main your neighbors and the city depend on.

This is why municipal FOG programs across the country take the same position. From Portland to agencies in Texas, the goal is the same. You remove grease from the wastewater stream. You do not liquefy it so it travels farther before it clogs something. Hot grease that solidifies on a pipe wall restricts flow. In time, it backs the line up. That backup does not respect property lines, so a clog you sent downstream can come back as an overflow at your own door or a neighbor's.

The compliant approach is to capture and physically remove grease, not chemically move it along. A few practices carry the load here, and none of them involve an additive.

• Run a properly sized, regularly pumped grease interceptor. The interceptor has to be large enough for your kitchen's flow, and it has to be pumped before it fills up. The widely used standard is the 25% rule: clean the interceptor when fats, oils, grease, and solids reach 25% of its capacity, with many jurisdictions adding a 30- or 90-day minimum. See how often to pump a grease trap for the interval details.
• Scrape and dry-wipe before washing. Scrape food scraps and grease off pans, plates, and cookware into the trash, and dry-wipe greasy surfaces before they hit the dish sink. Keeping grease out of the drain in the first place is the cheapest control you have.
• Collect used cooking oil separately. Store waste fryer oil in a sealed container for a rendering or recycling hauler. It never goes down a drain.
• Keep records. Hold onto your pump-out manifests and maintenance logs. Phoenix's FOG program is inspected, and recordkeeping is part of demonstrating compliance.

Doing these things keeps grease out of the interceptor's outlet and out of the city main, which is the entire outcome the prohibited products only pretend to deliver. For how the program registration and inspection side works, see the Phoenix FOG grease program and registration page.

This is the part that confuses a lot of restaurant owners, because they have an enzyme drain product under their own kitchen sink at home. The two situations are not the same.

A homeowner using an enzyme maintenance product on a residential drain is generally fine. There is no grease interceptor in a typical house, the waste volume is small, and the product is used as a slow, ongoing maintenance habit rather than a way to flush concentrated commercial grease past a control device. That use is covered separately on the do enzyme drain cleaners work page, and it is allowed as routine maintenance.

A food-service business is a different animal. A commercial kitchen generates concentrated grease in volume, it is required to have an interceptor, and the city's FOG rules exist precisely to keep that grease out of the public sewer. Using an enzyme, bacteria, or solvent product to push that grease through the interceptor is the specific commercial practice Phoenix prohibits. So the distinction is not really about the chemical. It is about whether the product is being used to defeat a required grease interceptor at a regulated food business.

Phoenix's FOG program is enforced through inspection. The Water Services Department can inspect a food-service establishment's interceptor and its maintenance. A facility can get cited for using prohibited grease-dissolving products. It can also get cited for running an undersized or poorly maintained interceptor, or for sending grease into the sewer. The penalties can include notices of violation, required corrective action, and fines. The business can also be charged for cleaning up any sewer overflow it caused. The cost is not just a fine. If your discharge helps cause a blockage and overflow downstream, the cleanup and damage costs can land on the business.

These are local ordinance rules, and the specific terms and enforcement steps can change. They can also differ between Phoenix and other Valley cities. So confirm the current rules directly with the City of Phoenix Water Services FOG program before you rely on any one practice. The municipal code and program documents are the authority. Not sure if your interceptor is sized right, if your cleaning interval is enough, or if a product is allowed? Have a licensed commercial plumber and the city review your setup. Do not trust a vendor's claim that a treatment is "approved."