Threats to the sewer system

Last reviewed:

The sewer system is designed to only collect and treat waste that breaks down naturally. However, on a daily basis we have to deal with 'unsuitable waste' that is wrongly disposed of down drains and toilets.

These are often materials that don't break down naturally or are very hard to remove and as a result, cause problems at our sewage treatment works.

They also affect the quality of the treated water that we recycle back to the environment and the quality of sewage sludge to be recycled to land. 

Unwanted materials

We remove over 25,000 tonnes of debris from our sewage system every year. Cotton buds are a particular problem, because their small size enables them to pass through the finest screens within our sewage treatment process.
 
It is estimated that over 100,000 cotton buds per week are disposed of in the sewer network in our region alone. 

Disposing of inappropriate solid waste, such as cotton buds, 'disposable' nappies, and sanitary products down the toilet or drains can lead to severe sewer blockages, which can result in domestic sewer flooding and lead to untreated sewage spilling into rivers and streams.

Razor blades, plastic wrappings and clothing such as ladies tights, also cause problems at our sewage treatment works, making it more difficult to treat the wastewater.

We urge customers not to use the toilet as a dustbin. Items should instead be disposed of in the bin.

Fat disposal

Over the past ten years there has been an increase in the amount of fat disposed into our sewers. 

Over 55,000 sewer blockages are cleared each year, of which approximately 50 per cent are the result of fat, oil and grease.

These blockages can cause sewer flooding to both roads and buildings, including houses.

We are supportive of the installation of properly maintained fat traps at fast-food outlets, and the use of fat collection services and recycling of fat for bio diesel. 

Fats produced in the kitchen at home should be allowed to cool and disposed of in the bin.

Alternatively, animal fats can be mixed with seeds and nuts and put out as bird feeders.

Also in this section

Foul and surface water sewers Are you polluting? Identifying misconnections Who is responsible?