Thames Water clears 500-metre fatberg near Heathrow

• Thames Water engineers discover 500-metre-long fatberg clogging a sewer outside Heathrow airport.
• The congealed wall of fat is the equivalent of more than 700 suitcases laid end to end. 
• Engineers spent over a fortnight using excavation tools to chip away at the solid mass before blasting the remaining deposits with high-pressure water jets.
• These blockages lead to over 60% of sewer floods and cost around £40 million annually.

Thames Water engineers have unearthed a half kilometre wall of congealed fat lurking beneath the roads outside Heathrow Terminal 5, a blockage big enough to stretch between two airport terminals.

The fatberg filled around 500 metres of the 1,030-metre sewer, the equivalent of more than 700 suitcases laid end to end. It was discovered beneath Poyle Road, an area dominated by industrial units and airport perimeter businesses. As this section of sewer stays full for long periods, fat deposits build up quickly, affecting multiple manholes and causing repeated blockages.

The discovery is a stark reminder that what goes down the drain doesn’t simply disappear. Clearing blockages of this scale is costly, disruptive, and ultimately paid for by customers.

Across the Thames Water network, fats, oils and grease cause more than 20,000 blockages every year, accounting for 28% of all sewer blockages. These blockages lead to over 60% of sewer floods and cost around £40 million annually.

Research commissioned by Thames Water shows that many residents across London and the Thames Valley are unknowingly contributing to the challenge. A recent survey found that: more than 40 per cent of people had poured meat juices down the sink, 39 per cent gravy, 18 per cent animal fats including lard, 28 per cent cream, 21 per cent custard and 10.5 per cent hummus – all fatty and oily substances that can congeal in pipes and block them up. They can wreak havoc on drainage systems and, in the worst cases, lead to homes and gardens being flooded with sewage and pollution in our rivers.

All of these substances can congeal in pipes, causing blockages that lead to sewer flooding, polluted waterways and, in the worst cases, sewage backing up into homes and gardens.

Removing the Heathrow fatberg took over two weeks, from 16 February to 10 March, with teams still working on a dig to repair a collapsed section of the sewer. Engineers used excavation tools to chip away at the solid mass before blasting the remaining deposits with high-pressure water jets.

Steve Crabb, Head of Waste Operations for Thames Water home counties, said:

“This was a stubborn and sizeable blockage, but our teams have worked relentlessly to break it down and keep the network flowing. Fatbergs like this are entirely avoidable, and we’re urging everyone including businesses to think carefully about what they pour down the drain to help us prevent repeats of this in future.”

Thames Water works closely with businesses to prevent grease entering the sewer system, offering guidance on proper kitchen waste management, the use of grease management systems, and the legal implications of discharging fats, oils and grease into drains.

To help residents and businesses “starve the fatbergs”, Thames Water is sharing the following tips:

• Scrape food scraps from any dirty dishes, pans or utensils into the bin, or ideally a food waste caddy and not into the sink. 
• Ensure your plughole has a strainer fitted to catch food scraps and prevent them from going down the drain.  
• Don’t pour liquid foods down the sink i.e. fats, oil, cream and milk.
• To dispose of surplus hot oil, let it cool, then scrape it into the bin or consider storing it in a container to take to the local recycling centre. 
• Avoid pouring boiling water or bleach down the drain – this only moves the problem further down the pipes and does not resolve the issue. 
• Only flush the three Ps down your loo – Pee, Poo and (toilet) Paper. Do not flush wet wipes, cotton buds or paper towels. 
• Always clean your drain regularly – if it looks like it’s draining poorly, better to sort it sooner rather than later.

More advice is available on Thames Water’s ‘Bin It - Don’t Block It’ page.