For restaurants, cafés, pubs and takeaways, a blocked drain can mean closing the kitchen at short notice. The most common cause is fat, oil and grease, often shortened to FOG.
Why grease causes so many problems
Grease goes down the sink hot and liquid, then cools and sets on the inside of the pipe. Food particles stick to it, and layer by layer the pipe narrows until it blocks. In a busy kitchen this can happen surprisingly fast, and the build-up often extends from the sinks to the gullies outside and into the main drain.
Grease that gets into the public sewer contributes to “fatbergs”, which water companies spend a great deal clearing each year.
What the rules say
- Sewers. Under the Water Industry Act 1991, it is an offence to put anything into a public sewer that is likely to interfere with its free flow. Water companies can take action against businesses whose grease causes sewer blockages.
- Grease separators. Building Regulations guidance (Approved Document H) says drainage from commercial hot food premises should have a grease separator, or another effective means of removing grease, where there is a risk of grease entering the drains.
- Waste oil. Used cooking oil should be stored and collected by a licensed waste carrier, not poured away.
Check the current requirements with your water company and local authority, as they are the ones who enforce them.
Practical ways to prevent blockages
- Scrape plates and pans into the food bin before washing.
- Use sink strainers and empty them into the bin.
- Never pour oil or fat down any sink or drain, including mop sinks and floor gullies.
- Maintain grease management equipment, such as grease traps or separators, and keep records of emptying and servicing.
- Train staff, including new and temporary staff, as habits make the biggest difference.
- Plan drain cleaning. Regular drain jetting removes grease from pipe walls before it becomes a blockage.
Signs your kitchen drains need attention
- Sinks and floor gullies draining slowly
- Smells in the kitchen or customer areas
- Grease visible in outside gullies or inspection chambers
- Blockages that return every few weeks
Planned maintenance versus emergency call-outs
An emergency blockage during service costs far more than lost food. A drain maintenance plan sets how often your drains are cleaned based on how quickly grease builds up, with a record of each visit. That record is also useful if your water company or landlord asks what you are doing to manage grease.
Find out more about our commercial drainage work, or read how often drains should be cleaned.