# Restaurant Floor Drain Backing Up? Causes and Fixes > Restaurant floor drain backing up when the dish machine runs? Find out whether it's a full grease trap, a blocked outlet or a greased-up line, and what to do. URL: https://greasetrapcleaningtampa.com/guide/kitchen-floor-drain-backing-up/ Decision Guide # Why Is My Restaurant Floor Drain Backing Up? Three places the blockage can be, how to tell which one you have, and what to do before service tonight. Updated November 14, 2026 [Grease Trap Cleaning Tampa](https://greasetrapcleaningtampa.com/) finds most restaurant floor drain backups in one of three places: a grease trap that's full, an outlet blocked by solids or a missing tee, or a kitchen line narrowed by grease that got past the trap. A backup when the dish machine runs usually means the line can't carry a big discharge. ## What to do right now 1. **Stop the water.** Pause the dish machine and the sinks that share the line. 2. **Keep the floor safe.** Close off the area and keep food and prep surfaces clear. 3. **Look at the trap.** If you can safely lift the lid of an indoor trap, a full trap or one that’s overflowing is your answer. Call for [emergency pumping](https://greasetrapcleaningtampa.com/emergency-grease-trap-pumping/). 4. **Don’t pour chemicals or boiling water.** Hot water moves grease further down the line, where it sets again. ## Three places the blockage can be Where Signs Fix **The trap is full** Trap visibly full or overflowing; backup near the trap Pump-out **The outlet is blocked** Trap full of water but not grease; slow everywhere downstream Pump-out, clear outlet, check tee **The line is greased up** Trap not full; backups when large volumes drain [Hydro jetting](https://greasetrapcleaningtampa.com/commercial-kitchen-hydro-jetting/) ## Why grease reaches the line - **The trap is overdue.** Past 25%, grease starts leaving with the water. - **A broken baffle or missing outlet tee** lets grease short-circuit straight through. - **Hot water.** St. Petersburg’s best-practice manual notes that water above 140°F dissolves grease, which then re-solidifies downstream as it cools. - **A fixture that bypasses the trap.** Every grease-producing fixture should drain through it. - **Food solids.** The same manual recommends sink strainers and removing garbage disposals, which send solids into the trap and the line. ## Stopping it happening again Jetting clears the line. It doesn’t fix the cause. Pump the trap on a schedule set by measured fill, get broken baffles and tees replaced, and keep sink water under 140°F. See [hydro jetting vs snaking](https://greasetrapcleaningtampa.com/guide/hydro-jetting-vs-snaking-grease-lines/) and [grease trap repair](https://greasetrapcleaningtampa.com/grease-trap-repair/). Bottom line Stop sending water, find whether the trap is full, and if it isn't, the line needs jetting. Fix the reason grease reached the line or it will happen again. If it's backing up now, call [(727) 476-9241](tel:+17274769241). [Related service Commercial Kitchen Hydro Jetting Grease-coated kitchen lines between fixtures, trap and sewer cleared with high-pressure water, not just punched through. See the service](https://greasetrapcleaningtampa.com/commercial-kitchen-hydro-jetting/)[Also related Emergency Grease Trap Pumping Overflowing trap, backed-up floor drains or a violation deadline. Call, and here's what to do while you wait. See the service](https://greasetrapcleaningtampa.com/emergency-grease-trap-pumping/)[Also related Indoor Grease Trap Cleaning Under-sink and in-floor traps cleaned, logged and hauled away, including automatic grease removal devices. See the service](https://greasetrapcleaningtampa.com/indoor-grease-trap-cleaning/) Want a quote? [(727) 476-9241](tel:+17274769241) ## Questions about this ### Why does my floor drain back up only when the dishwasher drains? A dish machine dumps a lot of hot water at once. A line narrowed by grease can handle a trickle but not that surge, so it comes back up through the lowest opening, usually a floor drain. ### Will pumping the grease trap fix a floor drain backup? Only if the trap is the blockage. If the trap isn't full, the problem is in the line before or after it, and that needs jetting. ### Can I use a drain cleaner on a kitchen floor drain? Caustic and solvent drain cleaners can harm the sewer and the people working on it, and St. Petersburg's best-practice manual says not to discharge them. Tampa also requires approval for any grease additive. ## More guides - [How Much Does Restaurant Hydro Jetting Cost?Typical Florida prices for jetting a kitchen grease line, what pushes a job up, and why the trap should be pumped in the same visit.](https://greasetrapcleaningtampa.com/guide/hydro-jetting-cost-restaurant/) - [Hydro Jetting vs Snaking: Which Clears a Grease Line?How each method works on grease, why one fix lasts longer, and when the cheaper option is fine.](https://greasetrapcleaningtampa.com/guide/hydro-jetting-vs-snaking-grease-lines/) - [Buying a Restaurant? Grease Trap Requirements to CheckWhy a change of ownership matters to the grease program, and the checks to make before you sign.](https://greasetrapcleaningtampa.com/guide/buying-a-restaurant-grease-trap/) - [How Do You Choose a Grease Trap Company?Eight questions that separate a hauler who keeps you compliant from one who just empties the tank.](https://greasetrapcleaningtampa.com/guide/choosing-a-grease-trap-company/) - [Can I Clean My Own Grease Trap?Which units staff may clean, the disposal limits that apply, and a step-by-step routine that meets the logbook rules.](https://greasetrapcleaningtampa.com/guide/can-i-clean-my-own-grease-trap/) Get an exact price for your kitchen Two quick steps. We call back to confirm. Faster by phone: [(727) 476-9241](tel:+17274769241) Rather talk it through? Call now. Call any time. If we can't pick up, leave a message and you'll get a call back. [(727) 476-9241](tel:+17274769241) [Request a quote](https://greasetrapcleaningtampa.com/contact/)