Fat from Christmas table clogs up sewage systems in cities

Fat in the sewage system, photo: Martin Němec

It is a well-known fact that the traditional Czech heavy Christmas menu is a burden on the digestive system. Fewer people know, though, that fat is not only bad for the gall-bladder and arteries but can also cause problems to the sewage system. Especially in densely populated areas the sewer pipes and sewage treatment plants experience something of a fat overdose at Christmas time. The problem is faced by all cities and some have already taken measures against it.

Fatty foods are part of the typical Czech diet all year round but the Christmas holidays are a genuine fat feast. On Christmas Eve most Czech families eat fried carp. According to the Czech Fish Farmers Association, over four thousand tonnes of live fish are sold in the Czech Republic before Christmas, 350,000 fish in Prague alone. In hundreds of thousands of kitchens around the country, all those fish are fried in oil at approximately the same time. On Christmas Day the situation is repeated with roast duck and goose served in many households. After the festive dinner, in most cases the grease is poured down the drain.

That causes problems especially in winter. As it cools down, grease in the pipes curdles into lumps and mixes with other impurities, such as hair and potato peels, blocking the pipes and putting further strain on sewage treatment plants where it can jam the pumps.

In sewage treatment plants part of the clotted grease is skimmed and lumps of grease are shovelled out of the tanks. Miroslav Novák describes the situation at the sewage treatment plant in the city of České Budějovice which has a population of over 90,000.

„We collect some 9 to 10 tonnes of fat from the system during the Christmas holidays.”

Sewage treatment plants around the country are on alert at Christmas time, ready for extra work and costs and so are other workers in sewage utilities. Cooking oils and animal fat from roasting clogs up street sewer pipes as well, as Jitka Kramářová from the water and sewage utility in České Budějovice comments:

Fat in the sewage system,  photo: Martin Němec
“We have already cleaned three sewage lines and one blocked sewage shaft.”

Few people are aware of the fact that disposing of fat in the drain is actually prohibited. Some towns and cities have distributed special containers for kitchen grease. In Ostrava people are encouraged to store their used fat in bottles and bring them to waste collection points for recycling. Five to ten litres of household cooking fat is collected every month in special bins in the town of Chrudim, according to the local authorities. Although in České Budějovice the locals seem to largely ignore the eight used fat containers, the municipal authority is planning to increase their number around the city.

The České Budějovice sewage treatment plant says it will now take at least a week to get rid of all Christmas grease in the tanks. Unless the locals learn to use the fat recycling bins, the situation will repeat again next Christmas as the typical Czech Christmas menu is not likely to change dramatically any time soon.