Fat, oil and grease (FOG) How to prevent blockages & who’s responsible?

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Fat, oil and grease (commonly known as FOG) are one of the leading causes of blocked drains in homes and commercial properties across the UK.

Although pouring cooking oil or washing greasy pans down the sink may seem harmless, these substances cool and solidify inside pipework, gradually restricting the flow of wastewater.

Left untreated, a build up of FOG can lead to blocked drains, unpleasant odours, slow draining sinks, overflowing waste pipes and in severe cases, costly damage to drainage systems.

Why Does Fat and Grease Build Up?

Kitchen sinks are the most common source of fat related drain blockages.

During cooking and washing up, oils, fats, butter, gravy, sauces and food scraps are often rinsed into the sink.

While these substances may be liquid when hot, they quickly cool once inside the drainage system. Over time they stick to the inside of pipes, trapping food particles and other debris. Each layer of grease narrows the pipe until water can no longer flow freely.

Common items that should never be poured down the sink include:

Cooking oil and frying fat
Butter and lard
Meat fats and gravy
Cream-based sauces
Food scraps
Coffee grounds
Eggshells

Signs Your Drain May Be Blocked

Early signs of a developing blockage include:

Water draining slowly from sinks.
Gurgling sounds from plugholes.
Unpleasant smells coming from the drain.
Water backing up into the sink.
Repeated blockages despite cleaning.

Acting early can often prevent a complete blockage and reduce the need for professional drain clearance.

How Can I Remove a Grease Blockage?

If the blockage is minor you may be able to improve drainage by:

Pouring hot (not boiling) water into the drain particularly if you have plastic pipework.
Using washing up liquid followed by hot water to help break down grease deposits.
Using a sink plunger to help dislodge small blockages.

Avoid relying heavily on chemical drain cleaners. These products may temporarily clear part of the blockage but can also damage pipework if used incorrectly and may simply push the grease further along the drainage system rather than removing it completely.

If water is no longer draining or the blockage keeps returning it is advisable to contact a professional drainage contractor who has the correct equipment to clear the obstruction safely.

Prevention Is Better Than Cure

The easiest and most cost effective way to prevent blocked drains is to stop fats, oils and grease entering the drainage system in the first place.

Good kitchen habits include:

Allow cooking oil and fat to cool before placing it in a sealed container and disposing of it with household waste or recycling it where local facilities are available.
Wipe greasy pans and plates with kitchen paper before washing.
Use sink strainers to catch food waste.
Dispose of food scraps in the bin rather than the sink.
Regularly flush kitchen waste pipes with hot water and washing-up liquid to help reduce minor grease deposits.

Small changes in everyday habits can significantly reduce the risk of expensive drainage problems.

Who Is Responsible for a Blocked Drain?

Responsibility for clearing a blocked drain depends on where the blockage is located.

Generally:

Homeowners are responsible for maintaining drains within the boundary of their property.
Private tenants should report blockages to their landlord or managing agent promptly. If the blockage has resulted from misuse (such as repeatedly disposing of fats, oils or unsuitable items down the sink) the tenant may be responsible for the cost of repairs.
Landlords are generally responsible for maintaining the property’s drainage system and ensuring it remains in good repair under the Landlord and Tenant Act 1985 unless the damage has been caused by a tenant’s negligence or misuse.
Shared sewers outside the property’s boundary are usually the responsibility of the local water and sewerage company.

If you’re unsure who is responsible your landlord managing agent or water company can advise.

Need Advice?

Blocked drains caused by fat, oil and grease are largely preventable with good kitchen practices. Preventing FOG from entering your drainage system not only reduces the likelihood of costly repairs but also helps protect the wider sewer network from avoidable blockages.

If you’re experiencing recurring drainage issues it’s always best to seek professional advice before the problem becomes more serious.