Thames Water has launched an investigation after thick, black oil was poured into the sewers, clogging up a pumping station and polluting Bracknell sewage works.

According to Thames, while there has been no impact on customers or the environment thanks to the speed in which it was spotted by engineers last week, a complicated and unpleasant clean-up procedure is now taking place to remove the substance.

The water company said that if the oil not been spotted quickly, it could have damaged vital equipment as well as creating a blockage in the sewers which would have had a devastating environmental impact.

Steven Gerrard, who manages works, said:

“Putting oil in the sewers is incredibly irresponsible and will take a lot of time and money to clean up. Luckily we have prevented it from having an impact on customers or the environment but the wider consequences could have been catastrophic.

“We would urge whoever is responsible to come forward so we can ensure this never happens again.”

The works serve thousands of households in the region and this is not the first time oil has made its way into the network. However, the quantity which has been put in this time is far greater meaning it is taking much longer to get rid of.

For the last week Thames Water staff have had to painstakingly skim oil off the surface of the water at the treatment works and will continue to do so until all of the pollutant has been removed.

Thames Water is asking anyone who has information about how the oil ended up in the sewer then to call them on 0800 980 8800.