Thousands of people in the UK are getting diagnosed with bladder and rectal cancers through drinking tap water.
Drinking water disinfection is essential for public health protection against waterborne infections. However, disinfection by-products (DBPs) are formed as an unintended consequence of water disinfection. DBPs form a complex mixture of hundreds of chemicals
Trihalomethane is formed and this is where long term exposure to this chemical has lead to thousands of people in the EU getting bladder cancer, and the situation has not changed.
You can though protect yourself from the chemical that causes bladder cancer by fitting special carbon type filters to your taps, normal filters do not work to get rid of Trihalomethane.
Defra have published a PDF on how safe our drinking water is and more information on Trihalomethane the chemical that caused bladder and rectal cancers .http://dwi.defra.gov.uk/research/completed-research/reports/DWI70_2_216%20THMs%20in%20drinking%20water.pdf
And the full publication by Environmental Health Perspectives https://ehp.niehs.nih.gov/doi/full/10.1289/EHP4495