Why kitchen drainage fails so predictably
Fat leaves the pot warm and liquid. Within a few metres of pipe, especially an external run in a Scottish winter, it cools and adheres to the wall. Each service adds a layer. Detergent emulsifies fat temporarily, which simply means it travels further before depositing, often into a shared run where the blockage affects other premises as well.
By the time a kitchen sink is running slowly, the pipe bore has usually been reduced by well over half. The failure is not sudden, it is simply the last day of a long process, and it always seems to fall on a Friday night.
Grease traps and how they are sized
A grease trap slows the flow enough for fats to separate and float, retaining them so they never reach the drain. Sizing is based on the flow rate from the appliances discharging into it, the number of covers and the type of food produced. An undersized trap does very little, because the water passes through too quickly for separation to occur.
Passive traps are cheaper and need frequent manual cleaning. Automatic units skim and collect the grease themselves and suit high volume sites, but they still need servicing. Neither works without a maintenance schedule, and an unemptied trap is worse than no trap because it eventually discharges its contents in one go.
A workable cleaning routine
- Scrape and wipe all pans and plates before they reach the sink or the dishwasher.
- Collect waste oil in sealed containers for licensed collection, never down the sink.
- Fit and clean strainers on every sink daily.
- Empty a passive grease trap weekly, or more often at high volume.
- Service automatic units to the manufacturer's schedule and keep the records.
- Plan a professional jet of the kitchen run at a set interval rather than waiting for a blockage.
Dosing systems and enzyme treatments
Bacterial and enzyme dosing systems can help maintain a run that has already been cleaned properly, breaking down the thin film that reforms between jetting visits. They are a maintenance aid, not a cure, and they will not clear an established fat deposit or excuse a missing trap.
Where they earn their place is on a site with a long external run or a history of problems, used alongside a jetting schedule rather than instead of one.
What environmental health and your landlord expect
Environmental health officers will look at whether fat is being prevented from entering the drainage system, whether there is a trap where one is needed, and whether cleaning is documented. A written schedule with dates and signatures is worth having ready, because being able to produce it immediately changes the tone of a visit.
Commercial leases frequently make drainage maintenance the tenant's responsibility, and a landlord may ask for evidence of servicing. A blocked shared run affecting neighbouring units is also a route to a dispute you do not want, particularly in a parade or a shopping centre.
Planned maintenance and out of hours work
We set up scheduled jetting for pubs, restaurants, hotels, takeaways and care premises across central Scotland, working outside trading hours so service is never interrupted. Each visit includes a camera check so you can see the run is at full bore rather than simply flowing on the night.
A planned visit two or three times a year costs a fraction of one emergency closure, and unlike an emergency it happens at a time you chose. We also provide reports and dated records suitable for environmental health, landlords and franchise auditors.
Training the team
Systems fail at the sink, not on paper. The people who actually scrape the pans decide whether the trap works, and turnover in hospitality means the briefing has to be repeated rather than given once. A laminated card at the wash up station and a line in the induction covers most of it.
Make it easy to do the right thing: a scrape bin within reach, a labelled oil container that is never full, strainers that are actually cleaned. Where a site does this consistently, the difference in what we pull out of the run at the next visit is obvious and measurable.
Questions we get asked
Is a grease trap a legal requirement?
There is no single blanket rule, but you must not discharge fats that cause a blockage, and environmental health and Scottish Water will expect adequate prevention where a kitchen is producing them.
How often should a kitchen drain be jetted?
Twice a year suits most restaurants, and quarterly suits high volume fried food operations or sites with long external runs.
Can you work outside opening hours?
Yes. Most of our commercial jetting is carried out overnight or in the early morning to avoid disrupting service.
Who pays if a shared run blocks?
It depends on the lease and the title, but a documented maintenance record is what protects you when the discussion starts.