What are Fats, Oils and Grease (FOG)?

FOG stands for fats, oils and grease and originate from food products such as butter, lard, vegetable oils, animal fats, meats, sauces and dairy products. They are generated during the preparation of food and from any cleaning/washing up processes. 

FOG usually comes from kitchens of Food Service Establishments (FSEs) where food is prepared, cooked or served. These can include restaurants, takeaways, pubs which serve cooked food, cafés, coffee shops, hotels, B&Bs, convenience stores and supermarkets, garage forecourt shops with delicatessen counters, food production kitchens etc. Blockages caused by FOG can result in raw sewage overflowing from sewers into business premises, public areas, streams or rivers causing an environmental and public health hazard.

Apply for a Trade Effluent - FOG (Fats, Oils & Grease) Licence

A trade effluent discharge to sewer licence (issued under Section 16 of the Local Government (Water Pollution) Act 1977, as amended) is a legal requirement if your business discharges trade effluent to a public sewer.

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The problem with FOG

  • Easy to pour down the drain: When fats, oils and grease are hot and are in liquid form, they pour easily down a drain or sink and appear harmless. However, when they cool, they solidify and build up inside the pipes causing serious blockages.
  • Not easy or cheap to remove: The removal of FOG from sewers is a difficult and expensive process. Irish Water is responsible for the operation and maintenance of public sewers. This includes clearing blockages in sewers caused by FOG. However, blockages in private drains connecting to the public sewer are the responsibility of the business/property owner.
  • Your liability in case of blockages: If FOG is discharged from your premises and causes blockages and flooding, you may be liable for covering the costs. This would include hiring specialist machinery, specialist personnel, loss of stock and premises clean up.
  • Prevent blockages: If you are operating to best practice, you should already have a grease trap or grease removal unit(s) fitted at your business premises. It’s important to ensure this trap/removal unit is the correct size and is kept fully serviced in accordance with manufacturer’s recommendations.

You should also keep your effluent records up to date with details like oil recycling and FOG control equipment maintenance.

Follow our checklist and protect your drains from FOG

The Do's

Do wipe and scrape plates, pans and utensils into a suitable bin before washing 

Do collect all used cooking oil into a suitable container and arrange for its collection by an appropriately authorised collector

Do use strainers in sink plug holes, then empty into a suitable bin 

Do clean equipment in dedicated wash-up sinks  


Do mop up grease spills with kitchen towel and put them in an appropriate bin 


Do make sure your grease trapping equipment is properly maintained by kitchen staff/authorised contractors and maintenance details are recorded

The Dont's

Don’t put fats, oils or grease down the sink 


Don’t put food scrapings into the sink

Don’t pour fats, oils or grease down the floor drain

Don’t pour harmful chemicals down the sink or drain to try and dissolve fats, oils or grease


Don’t clean equipment in sinks designated for food preparation 

Don’t sweep kitchen waste into floor drains 

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