Water company efforts to protect the environment are “simply unacceptable”, the Environment Agency has said.
There were 56 serious pollution incidents last year, rising from 52 in 2017, the agency’s annual report said.
Only one of the nine major water companies in England is performing at the expected level, with most likely to miss 2020 targets, the agency added.
Trade body Water UK said the report was “disappointing” and the situation was “never black and white”.
Only Northumbrian Water achieved the highest four star rating.
In June, the firm agreed to pay more than £1.1m after accepting responsibility for five historical environmental offences.
Severn Trent Water, United Utilities and Wessex Water dropped from four stars to three stars, meaning they must improve their performance to reduce their impact on the environment.
Anglian Water and Thames Water remained on three stars and Southern Water, South West Water and Yorkshire Water achieved just two stars for their “unacceptable level of performance”.
South West Water was given a red rating for pollution incidents for “consistently demonstrating unacceptable performance”, while Southern Water and Thames Water failed to demonstrate they had robust plans to maintain secure water supplies.
The report follows the agency’s announcement that Southern Water is facing prosecution after it was hit with a record £126m penalty package over “shocking” failures in its sewage treatment sites.