How are commercial floor and trench drains cleaned?

The word "floor drain" gets used for several different fixtures, and they are not cleaned the same way. Aldevra, a commercial kitchen supplier, lists four common types:

• Floor drains: a basic round or square drain used for cleanup and mopping. Capacity is low.
• Floor sinks: a deep, recessed bowl with a grate, which allows an air gap. They are used for equipment such as ice machines and steamers. Our page on floor sinks versus floor drains and mop sinks covers where each belongs.
• Trough drains: a long rectangular channel, used in dish rooms and prep areas that handle a lot of water.
• Trench drains: a wider, deeper version of the trough drain, built for institutional kitchens that need maximum capacity.

Wikipedia's overview describes a trench drain as a channel-shaped drain with a grate over it, used where water has to be collected along a length of floor instead of at a single point. That shape is the reason trench drains collect debris along their whole run. Grease and food particles settle in the channel, not just at the outlet.

The type tells you how to clean it. A floor sink has a basket that comes out. A trough or trench has grates and a channel floor that need scrubbing. A plain floor drain has a strainer and a trap below it. Whatever the type, the outlet pipe below it is where the serious clogs form.

What clogs them. Five things do most of the damage:

1. 1Grease and fat. Fryer grease and grill runoff cool and harden inside the pipe. Fountain Valley's restaurant program says hot water, detergent, or degreasers do not liquefy grease long enough to escape your drains, so it re-hardens in the line.
2. 2Food debris. Scraps from plates, sweeping, and sink overflow collect in the trap and the pipe.
3. 3Soap residue and scum. Detergent binds with fat and food particles into a sticky sludge.
4. 4Mineral scale. The City of Phoenix's 2025 water quality report notes that hard water can cause scaling in pipes and on plumbing fixtures. Our page on how hard Phoenix water is has the numbers.
5. 5Foreign objects. Utensils, wrappers, gloves, and other items slip through the grate.

Most of these are avoidable. The first three are the same problem that fills a kitchen main line, which is why a floor drain that keeps slowing down is often telling you about the pipe downstream. Our page on why a commercial kitchen drain keeps overflowing explains how the coating builds, and what FOG is covers the basics.

Aldevra's recommended cadence is a good template because it is short and it is specific:

Aldevra's guidance keeps returning to the same habit: remove and clean the basket thoroughly. Two habits we recommend on top of it are training staff to scrape solids into the trash and never into a drain, and keeping a record of clogs and cleanings for inspection purposes.

A note on enzymes and hot water. Aldevra’s general routine includes enzyme cleaner and hot water flushes, but local FOG rules govern whether that advice can be used. Phoenix prohibits enzyme dosing to dissolve grease past a food-service interceptor; do not apply the vendor routine there. They do not replace jetting, and they do not replace pumping the grease interceptor. City grease programs also warn that hot water and degreasers can push grease past an interceptor before it hardens again, which is why some cities restrict them. Our pages on whether enzyme treatments are allowed in Phoenix and whether hot water jetting clears grease lines better explain the limits. Check your city's rules before you build enzyme dosing into a routine, and ask your plumber what your interceptor is built to handle.

When a floor drain slows, work up from the least invasive step, because each step costs more and risks more than the last:

1. 1Pull the strainer and clean it. Aldevra's daily routine starts here: remove the strainers, scrub them, and flush with hot water. A clogged strainer is often the whole problem.
2. 2Clear what is in the drain by hand or plunger. A firm plunge or a wet/dry vacuum on the open drain can pull out soft debris near the grate. Seal the grate opening when plunging so the force goes down the pipe.
3. 3Cable the branch, gently. A cable can open a path through a soft blockage. Forcing it risks damaging the pipe and the trap, and it leaves the coating on the wall.
4. 4Add a routine treatment if your city allows it. Aldevra lists an enzyme cleaner as a weekly step. Check the local rule first, as covered below.
5. 5Hydro jet the branch. Suitable jetting can remove deposits from the pipe wall, but defects, roots and continued grease loading can still cause recurring clogs. General Pipe Cleaners, which makes both cable machines and jetters, explains the difference: a jetter's stream cuts grease off the walls of the pipe and flushes it away, while cables are ideal for cutting roots and retrieving objects.

The first steps are things a kitchen crew can try. The last one belongs to a plumber. As our page on cable versus jetter for a commercial main line explains, a cable opens a hole and leaves the coating behind, and the drain slows again in a few weeks. If you find yourself on step three every month, the pipe needs cleaning, not the drain.

Dry traps and trap primers. There is one floor-drain problem that has nothing to do with clogs. Every floor drain has a trap, a curved section that holds water and blocks sewer gas. Wikipedia's article on trap primers notes that these water seals are subject to evaporation in floor drains that are used infrequently, and that once the water is gone, sewer gases can enter the building.

A trap primer is a device that keeps the seal topped up. Wikipedia lists several types: a simple diversion from a nearby sink drain, a pressure-activated primer connected to the water supply that responds to pressure changes such as a nearby toilet flushing, timer or occupancy-based systems, and outlets built into laundry faucets. It adds that codes most often require primers for basement floor drains that are used only if the basement floods.

For a commercial building, the practical point is this: a floor drain that is rarely wet, such as one in a mechanical room, a storage area, or a restroom that sees little use, can dry out and start smelling. Pouring water into it, or having a primer installed, fixes the smell without any cleaning at all. If a floor drain smells even though it drains fine, check the trap before you blame the pipe. Our pages on what a floor drain backup means and sewer gas smell in a commercial building cover the other causes.

The reasons to stop and call a plumber are short: clearing attempts that keep failing, sewage or grease trap overflow, strong odors that persist, water visibly backing up, and a clog whose location is unknown or out of reach. Sewage coming up in a food establishment also triggers the Food Code's requirement to stop operating in the affected area and notify the health authority. If any of those apply, the fix is below the drain, not in it.

Branch lines to floor drains are cleaned like any other drain line. A typical plumber's approach is to open a cleanout, or pull the strainer when there is no other access, run a camera to see the pipe, jet the branch line with a head sized for the diameter, flush, and camera it again. Our page on what happens on a commercial drain cleaning call walks through that visit.

What to expect from a good cleaning. The crew should protect the floor around the drain and say how the water will be handled, because jetting moves water and debris through the line. They should tell you what the camera showed. They should recommend an interval, and it should be based on what they found and how heavily the kitchen is used, not a round number. If a drain keeps clogging after a proper jetting, the camera usually shows why: a low spot, an offset joint, or a branch that is too flat to carry solids. Those are repair questions, and no amount of cleaning solves them.

Keeping the kitchen open. Floor drains are often cleaned as part of a planned visit, and most planned work can fit around service. See whether a restaurant's drains can be cleaned while it stays open for how to schedule it and what changes if sewage comes up.

Routine care can reduce avoidable blockages, but drainage defects and changing use can still require repairs. A drain that is ignored becomes the place where a slow kitchen line first shows itself, usually at the worst time.

A short checklist for a kitchen or a commercial building:

• Pull and scrub strainers daily and empty baskets every shift.
• Keep a written log of clogs and cleanings.
• Schedule trench and trough deep cleaning monthly.
• Have the interceptor pumped on its schedule. See how often to pump a grease trap.
• Keep water in rarely used floor drains, or ask about a trap primer.
• Call a plumber when the cable comes out every month.

HQ offers commercial drain cleaning and hydro jetting for floor drain branches and kitchen lines, with 24/7 emergency service, free estimates, and the price given up front, before work starts. If you want a regular schedule in place, our page on a commercial plumbing preventive maintenance plan shows what one covers.