Enough lard to fill nine double decker buses is being removed from sewers under London's Leicester Square, by our team of hardy flushers.

The putrid fat build-up is the result of years of sewer abuse, which is when anything other than water, human waste and loo roll is put down drains. In Leicester Square's case, an estimated 1,000 tonnes of fat is being cleared in the largest-ever sewer clean-up of its kind.

We spend £12m a year clearing around 55,000 sewer blockages across London and the Thames Valley. Half of these could be avoided if people stopped abusing the sewers.

Our flushers, whose job it is to keep the sewers moving, are wearing full breathing apparatus and using shovels to dig out the fat. Powerful jets are being used to break down the fat-bergs inside the sewer.

Although the flushers are used to getting their hands dirty, this is the worst blockage they have come across. They've had difficulty even accessing the sewer as it was blocked by a four-foot wall of solid fat.

Just because you can put things down your sink or loo doesn't necessarily mean you should. In some cases it can literally come back to haunt you or a neighbour - in the form of sewage backing up in your drain and flooding your home or garden.

Every year 7,000 homes and gardens across London and the Thames Valley get flooded with sewage as a result of blockages - which is just horrible.

Cooking fat down drains is a big 'no no'. As soon as it is poured away it cools down quickly and sets hard forming a solid obstruction. Other household products such as wet wipes, sanitary products and cotton buds make things worse still, sticking to the fat and forming solid blockages. Even if these products claim they're flushable, they're not!

Work started beneath Bedford Row at the end of June. We are now working our way through the West End, including Holborn, Long Acre (near Covent Garden) Leicester Square, Piccadilly and up to Half Moon Street. The clean-up could take up to two months in total.