A drain in a commercial kitchen sink doesn’t get clogged like a drain in a household sink. Fats, oils, grease (FOG), starch (rice, pasta, potato), fine food scraps, and detergent residue are the main things that cause problems in restaurants and cafés. Over time, these things adhere to the walls of the pipe and produce a slippery, stinky layer called biofilm. That coating makes the line smaller, slows down drainage, and causes clogs to happen again and again.
This guidance provides a realistic, business-only standard operating procedure. It tells you what to do about smells, slow drains, full blockages, and when to stop and call a plumber. The goal is clear: keep the drain moving, cut down on smells, and avoid downtime.
Cleaning Checklist
What makes drains in commercial kitchen sinks get clogged?
Most of the time, these things cause clogs in commercial kitchens:
FOG, or grease and oil buildup
Even if workers never “pour grease down the sink,” grease still gets into drains from dirty pans, plates, and rinse water. Grease gets thicker and adheres to pipes when the water cools. That sticky coating holds everything else in place.
Starch that becomes paste
When you mix starches like rice, pasta water, and potatoes with grease and detergent, they turn into a sticky sludge. This is a big reason why drains in busy kitchens get clogged.
Food crumbs and labels
Strainers, tailpieces, and traps can get clogged with little bits of food, herbs, coffee grounds, and other things. Labels from containers are also popular offenders since they stick to the walls of pipes.
Odour and biofilm
Biofilm is more than just “dirt.” It is a layer of microorganisms and waste that is alive. Even if the drain is still working, it makes strong scents and flies come out of the drain.
Diagnose in 30 seconds: backup, sluggish drain, or odour
Determine the symptom before taking any action. Every symptom suggests a different solution.
1) Just smell (the drain is still moving quickly).
Possible causes include a filthy strainer, residue on the drain throat, or biofilm in the P-trap or tailpiece.
2) Slow drain (water moves slowly out of the drain)
Most likely causes are materials trapped in the trap, inadequate air flow due to partial blockage, and constriction from grease and starch accumulation.
3) Backup (no drainage, standing water)
A complete blockage in the trap or farther down the branch line is the most likely cause. In certain locations, it may also be related to problems with the grease interceptor or a downstream restriction that impacts several fittings.
Commercial kitchen safety guidelines for sink drain cleaning
It takes more than a “quick fix” to clean a slow or clogged sink drain in a commercial kitchen. Before anyone begins, a few basic controls must be put in place because this is a food hygiene and safety duty. For broader tips on avoiding common kitchen cleaning mistakes, ensure your team follows best practices.
1) Take charge of the space first.
Keep people away from the sink area and immediately post a wet floor sign. The greatest risk in crowded commercial kitchens is someone slipping while carrying heavy trays, hot food, or sharp objects. Until the floor is dry and the task is completed, try to keep the area closed off with a barrier, a trolley, or a clear “do not enter” sign.
2) Always wear basic PPE
At the very least, wear gloves and eye protection. Splashback from drain work frequently contains bacteria, detergent residue, and grease. Because individuals frequently lean over sinks without knowing how quickly water might swish back, eye exposure is a common accident. Upgrade to a mask and an apron if you are dealing with strong odours, obvious dirt, or possible contamination.
3) Avoid combining substances.
Chemicals should never be combined, even if you believe that “a little extra will help.” You frequently don’t know what product was used earlier in the day in professional situations. Bleach can emit harmful gases and cause severe respiratory and ocular discomfort when used with acids or unidentified cleansers. Don’t add extra product if you are unsure of what is currently in the drain.
4) Consider sewage-like water close to prep areas to be a sanitary issue.
Stop right away and take action if you see black water, a sewage-like odour, or an overflow that reaches floors close to places where food is prepared. That is not a typical cleaning problem. It turns into a contamination concern and needs to be dealt with in accordance with your site’s incident and hygiene procedures. To ensure that the proper cleaning and documentation procedures are followed, isolate the area, stop employees from passing through it, and notify the manager or supervisor.
5) Adhere to your site’s plumbing access regulations.
Do not try to open plumbing fittings or touch traps if your site policy prohibits it. Elevate to a licenced plumber or maintenance. For good reason, many kitchens have explicit regulations: improper fitting removal might result in leaks, flood the space, or expose employees to tainted water. When in doubt, pause and give it to the appropriate individual.
The commercial drain-cleaning kit (keep it handy)
When employees can’t find the necessary tools, a commercial drain SOP doesn’t work. Keep a kit with labels by the sink:
- Heavy-duty drain strainers or basket strainers for each bay
- A little bottle brush and a nylon detail brush (for cleaning the tailpiece)
- A bucket or drain pan and towels that soak up water
- Sink plugs (which are very crucial for multi-bay plunging)
- A bellows plunger has a better seal and a harder push than cheap plungers.
- Hand auger (drain snake) that works with sinks
- An enzyme drain maintainer that has been approved by the label for regular cleaning (not emergency unclogging)
Optional for maintenance groups:
- Wet/dry vacuum (to get rid of standing water quickly)
- A small adjustable wrench and some simple trap tools (only if staff are allowed)
SOP: How to clean a commercial sink drain (odour or early buildup)
When the sink drain smells, the water is still running, or you want to stop a clog before it becomes a bigger problem, use this SOP. The goal is to get rid of grease film and residue as soon as possible, not to use a “quick chemical fix.”
Step 1: Take out the strainer and clean it
Take out the strainer basket and give it a good cleaning. The strainer is the main source of smell in many commercial kitchens. It holds food scraps and builds up a greasy film that traps smells.
- Put empty solids in the right trash can.
- Scrub the inside and outside of the basket, even the rim and bottom.
- Take out any scraps, stickers, labels, or plastic pieces that may be stuck in the mesh.
Tip for staff: Don’t “rinse and hope.” Grease film frequently will not rinse off adequately. If it still feels slippery, it isn’t clean yet.
Step 2: Clean the splash zone and drain throat
This is the top of the drain opening where things get stuck, and it can smell terrible rapidly even when the drain is working well.
- Brush the upper orifice of the drain, which is the throat.
- Wipe down the area around the drain, even the sink top at the entrance.
- Clean and wipe the overflow slots in the sink as well.
Why this matters: food residue and detergent buildup in this zone can develop odour fast, especially in warm kitchens.
Step 3: Controlled hot-water flush
Let the hot water run for one to two minutes. This warms up the line and makes the grease softer, which makes the next step work better.
- Make sure the water is at a safe temperature for the crew.
- To maintain the flow steady and not burst, don’t splash.
Important: In a professional kitchen, don’t use “boiling water only” as your main method. Heat makes oil easier to remove, but mechanical cleaning is what really gets rid of the film.
Step 4: Clean the tailpiece (the vertical pipe that goes down from the sink)
This is where a lot of commercial sink drains start to break down. Grease clings to the wall of the pipe and makes a ring. Food, starch, and waste become stuck in the ring, and the pile gets bigger.
- Use a nylon brush to clean the inside of the tailpiece from the top aperture.
- Not just the middle, but the walls on the inside.
- To break and remove the film, pull the brush up and down a few times.
Do this for each bay if the sink has more than one. A slow bay sometimes signifies that the tailpiece or trap area in that bay is getting clogged, even if the other bays still drain effectively.
Step 5: Use an enzyme drain maintainer and leave it on overnight.
If the drain is still flowing, enzyme drain maintainers can assist minimise biofilm and smell as part of routine preventative. The most important thing is how long you are in touch.
- Use after closing, when the drain won’t be utilised for hours.
- Follow the label’s instructions for how much to take and how long to contact.
- Don’t flush right away. The item needs to sit in line for a while to work.
Important: Enzymes do not work right away to remove clogs. They are for keeping things in good shape and stopping problems before they happen. Enzymes usually take too long to repair a clog that is already there.
Step 6: Check the flow and write it down
This step makes the SOP useful for a long time.
- Let the water run for 30 to 60 seconds.
- Check if the drain is clear and that the scent is less strong.
Write it down on the cleaning checklist with the date, time, and initials.
- This easy log helps you find patterns, like:
- “Every Friday the drain slows down” (because of the grease load at the end of the week).
- “After lunch shift it smells” (food trash and starch moving down the line).
- “One bay is always slower” (a buildup in that bay’s tailpiece that is just in that bay).
Fix a slow drain in a sink with more than one bay
Use this if the water drains slowly but still does.
Step 1: Close off the other bays
Before you plunge, plug up the other sink bays so that the pressure and suction stay on the slow drain. Open bays in multi-bay commercial sinks let air out and lower the force that moves grease buildup. Use plugs that fit tightly, and if one doesn’t seal well, use a wet cloth to make the seal better. This simple setup makes plunging work much better.
Step 2: Add water and plunge the right way.
Fill the plunger lip with enough water to make a strong seal. A bellows plunger is the best choice because it makes pressure changes stronger in lines with a lot of grease. Instead of gently splashing at the surface, plunge with firm, short strokes to build push and pull inside the pipe. Keep the plunger closed to the drain so that the pressure cycles can go through the line.
Step 3: Check the strainers and any visible debris again.
Take out the strainer after plunging and look for any debris that has come loose. Grease rings can hold onto bits of food, labels, and other things, and plunging may bring those things back up. Clear it out immediately so it does not drop back into the drain and cause the same slowdown again. If you need to plunge again, remove debris between attempts.
Step 4: Brush and flush again
Next, brush the tailpiece from the top opening to remove grease film near the sink, which is where many slow drains start. Focus on scrubbing the inner walls because buildup forms as a coating, not as a single lump. Flush with hot tap water to carry loosened residue through the line. Re-test flow for 30 to 60 seconds to confirm the drain is improving.
Step 5: Escalate if it keeps returning
If the drain improves but becomes slow again within a few days, the problem is likely deeper in the line as grease and biofilm rebuild. At that stage, plunging and top brushing usually provide only short relief. Escalate to maintenance or a contractor for snaking, trap cleaning, or professional jetting based on your site setup and policy. Also note patterns in what is going down the sink, especially oils, starch, and scraps, because that often explains repeat slowdowns.
How to remove a completely blocked commercial sink drain (with standing water)
Use this SOP if there is water in the sink and it won’t drain. The goal is to halt the overflow quickly, safely remove the water, and then clear the obstruction in a method that doesn’t make it slippery or cause a food safety problem.
Step 1: Don’t use the sink anymore.
Stop rinsing dishes or pouring anything down the sink as soon as you see that the drain is completely stopped. If you keep using it, it will nearly always overflow, which makes the kitchen a dangerous place to walk about. It also becomes a hygiene issue since unclean water can move towards prep areas and shoes can track it around the kitchen.
Step 2: Get rid of standing water in a safe way
Before you try to clean the drain, get rid of the water that is already there. If your site has a wet/dry vacuum, utilise that instead of a bucket because it’s faster and cleaner. When you clear the water, you can get to the drain opening more easily and snaking works better since the tool can catch the clog instead of just moving water around and splashing dirt.
Step 3: Look for a blockage at the top of the strainer and drain throat.
Take off the strainer basket and look at the drain neck at the top entrance. In a lot of cases, the “blockage” is either food waste that has built up or a greasy plug immediately under the strainer. Take away anything you can see and any material that has become compressed. Then, pour a little water on it to see if the flow comes back. If it still won’t drain, treat it like a deeper blockage and start snaking it.
Step 4: Use a hand auger to snake the drain.
Put a hand auger into the drain hole and turn it while you push it in. Keep turning the cable until it bites into the clog, then draw it back to get rid of the debris. Do this over and over until the cable slides more easily and comes back with less stuff. This usually means that the blockage is breaking apart. In industrial kitchens, grease blockages often come out in soft, sticky pieces. Have towels ready to clean up the mess and throw away the trash instead of flushing it back down the sink.
Step 5: Flush and test in stages
Instead of blasting the tap totally, flush with hot tap water in tiny bursts after you have taken out some material. You are checking to see if the line is opening up without causing a sudden overflow. If the water level goes down and the flow gets better, keep doing brief flushes until the drain works regularly again. If it backs up again right away, the obstruction may still be there and you may need to snake it further or escalate it.
Step 6: Run a short recovery routine after the flow comes back.
Do a quick recovery routine when the sink is draining again to lower the risk of it getting clogged again right away during the next service period. After closing, when the drain can sit unused for hours, clean the strainer again, brush the tailpiece to get rid of the grease film near the top, and then use an enzyme drain maintainer. This third step is not a quick remedy; it is meant to stop problems from happening again. It helps lower biofilm and smell, which makes it less likely that the drain will clog again soon.
When to stop and call a plumber (commercial warning signs)
If any of these occurs, you should call a plumber or maintenance right away:
- If the clog comes back in a few days (it keeps recurring), it usually signifies that the blockage is deeper in the pipe, not simply at the strainer or tailpiece.
- If more than one fixture is slow at the same time, like sinks and floor drains, it means there is a problem with the common line, not just one sink.
- Gurgling in other drains: Gurgling is usually a sign of trapped air from a partial obstruction or bad venting caused by a backup.
- If cleaning the strainer and tailpiece doesn’t help the stench, it’s probably because the line is broken or there is deeper infection.
- When you run the sink, wastewater shows up in other fixtures. This is a clear sign that there is a limitation downstream that is pushing water back through the system.
- You think there might be a problem with the grease interceptor or a blockage downstream. Grease interceptor problems and main-line constraints can produce quick, repeated clogs and health dangers. Because they deal with oil, food particles, and a lot of water every day
Commercial kitchens are more likely to have drain difficulties. If you keep cleaning the top but the drain gets blocked again, the problem is usually deeper in the line and needs to be looked at by a professional with tools like snaking, jetting, or grease system servicing.
The question about baking soda and vinegar in commercial kitchens
A lot of the workers know this “classic” way. It can help with faint smells and little amounts of residue towards the top of the drain in commercial cooking spaces, but it won’t work for significant oil and starch buildup.
Only use it for light maintenance if you need to. Your true results come from:
- Control of the strainer
- Cleaning the tailpiece and trap
- Correct diving (with bays blocked)
- Snaking when necessary
- A regular programme for maintaining enzymes after closing
Also, think about chemical safety. If you have used acids or other unknown chemicals in a drain, never add bleach or other chemicals to it.
A routine for cleaning the kitchen drain that stops clogs
A basic and consistent plan is the best way to handle commercial drains. You can stop grease film, food scraps, and starch buildup from becoming full blockages that stop service by doing a few small things on time.
Every shift
Don’t wait until the last minute to take care of your drains. Make it a part of your daily dish and prep routine. Before anything goes down the sink, scrape food leftovers into bins. Also, always have strainers in every bay so that scraps can’t get into the line. Before they overflow, empty the strainers. Food and grease will get stuck within the pipe and start to plug it. Also, don’t wash heavy grease directly down the sink. Instead, wipe out pans and trays first so that the oil doesn’t stay to the pipe walls and make that sticky ring that snags everything else. Similar principles apply to other greasy areas, like those covered in our article on how to clean a kitchen hood filter.
End of the day (close)
Closing time is when you stop tomorrow’s obstacle from happening. Take out the strainers and scrub them well, not simply rinse them quickly. Greasy film is a big cause of stench and buildup that happens over and over again. Brush the drain throat and tailpiece to get rid of the coating that builds up around the top of the line. Then, run hot tap water for 1 to 2 minutes to flush the loosened residue through. After the service is done, put an enzyme drain maintainer on and leave it overnight so it has time to work on the biofilm and smell.
Every week
Once a week, execute a thorough brush routine for all the bays so you’re not only cleaning the “worst” sink. This is also the best time to look for early warning signals like a slow-moving drain, gurgling sounds, a poor smell, or drain flies. These indications normally show up before a full blockage. Make sure that your crew isn’t putting starchy trash down the drain, including rice, pasta water, batters, or thick sauces. This is because starch turns into glue in pipes and mixes with grease to make clogs that are hard to remove.
Once a month (or more often in kitchens with a lot of work)
Monthly checks let you find problems with your system before they get too pricey. If your site policy allows it, set up a time to examine the traps and fittings for buildup, leaks, loose connections, or places where the flow is starting to slow down. Go over your FOG management process with your workers, paying special attention to how fats, oils, and grease are managed before washing. If you keep having problems even when you follow healthy daily routines, call a professional fo example, Westlink Commercial Cleaning to clean the line. This is because repeat blockages usually signal the limitation is deeper and needs the right tools to remove safely.
Quick troubleshooting guide for commercial drains
If the drain smells but flows fine
Clean strainer, brush tailpiece, apply enzyme after close.
If one bay is slow, others are fine
Plug other bays, plunge, then brush and flush.
If the sink backs up during peak service
Stop use, remove water, snake the line. If it returns quickly, call maintenance.
If floor drains smell too
This may indicate broader drainage buildup, not just the sink. Escalate to maintenance and review cleaning schedules.
Conclusion: Keep the drain open and the service going
It’s easy to guess how commercial kitchen cleaning sink drains will work. You may greatly prevent blockages and smells by using strainers to regulate solids, brushing to remove grease film, plunging correctly for multi-bay sinks, and running a nightly enzyme programme. If several drains slow down at the same time or clogs come back quickly, call for help right away. This usually suggests that the problem is deeper than the sink. If you want a professional check or clean, request a Free quote Today!.
Frequently Asked Questions
How can you determine if your commercial sink drain is clogged?
Look for water that drains slowly, makes a gurgling sound, smells bad, or is standing still. If more than one fixture is slow (like the sink and the floor drain), you should approach it as a broader problem.
Will a blocked drain in a busy kitchen fix itself?
Not usually. It might get better for a short while, but oil and starch buildup usually comes back quickly unless it is cleaned out correctly.
How do you tell if it’s only the strainer area or a deeper clog?
Take off the strainer and clean it. Then run water through the drain throat to clear anything you can see. If the flow is still slow or backs up, the blockage is probably further down the line.
What is the main reason why drains get blocked in commercial kitchens?
FOG (fats, oils, grease) mixed with starch and small pieces of food. When you mix them together, they make a sticky sludge that sticks to pipes and catches additional trash.
Why does a sink drain smell bad even though it works fine?
The tailpiece, trap, and branch line can all get biofilm and other stuff stuck in them. That coating might still smell bad and attract drain flies, even if it flows well.
How often should you clean the drains in a commercial kitchen?
It should depend on the amount and the risk. Kitchens that do a lot of work normally need to be cleaned and brushed every day, and they also need a deeper cleaning once a week. Keep an eye on slowdowns and smells, and then change the schedule.
Do enzyme drain maintainers work, and how long should they stay in place?
They help with maintenance and keeping smells away, but not with clogged drains. For them to work, they need to be in contact for a lengthy time, usually overnight after closure.
Are chemical drain cleaners safe to use in business sinks?
They are dangerous. They can hurt workers, break pipelines, and generate odors or splashes that are dangerous. In most kitchens, mechanical procedures like brushing, plunging correctly, and snaking are safer and more reliable.
Is it possible to blend bleach with other cleansers to make drain cleaning work better?
No. Mixing items might let forth harmful fumes that can hurt your eyes and lungs. Follow the instructions on the label and only use one product.
When should you call a plumber or maintenance and stop?
If the blockage comes back within a few days, if numerous fixtures are slow, if wastewater shows up in other drains, if there is a sewage-like smell or black water, or if you think there is a grease interceptor or main-line limitation, call right away.
