Fat trap

Experts at The University of Portsmouth are taking part in a three-year nation-wide study into how fats and oils from restaurants are congesting Britain's sewage pipes and costing utility companies dearly.

Water companies spend over £25 million annually in treating sewers clogged with fatty residues from restaurant waste. It causes reduced capacity in sewage pipes, creating blockages and in some cases can result in the backing up of waste into restaurant toilets and into people's homes. It has also been linked to flooding in areas where combined sewers carry both sewage and surface water.

The problem has been connected in particular to fast food restaurants and as part of the study the University's waste-water experts will investigate the effects of different types of oil and fat used in various types of cooking.

Dr. John Williams of the University's civil engineering department said: "Problems start when hot fat is poured down the sink, which goes solid, as it cools in the pipe and furs up the drains. The problem is worse in areas where there is a high concentration of restaurants."