The Environment Agency has called for tougher penalties to be introduced for those guilty of water pollution.
Although the number of serious incidents has fallen by almost two-thirds since 2001, more than 300 damaging leaks still occurred across the UK in 2016.
The organisation says agriculture is the sector most responsible for water pollution and adds the frequency of pollution incidents from water companies also still occurs at a rate of more than one a week.
Despite acknowledging water quality has significantly improved over the last 30 years, the Environment Agency reports more than half of the country’s rivers contain unacceptable levels of phosphorus, caused by sewage effluent and pollutants from farmland.
This chemical damages waterways and ecosystems by producing algae and depleting oxygen.
The non-departmental public body says businesses and the public must do more to protect the environment by disposing of household chemicals responsibly, not putting fats and oils down the drain and minimising their use of single-use plastics.
Chair Emma Howard Boyd said: “There are still far too many serious pollution incidents which damage the local environment, threaten wildlife and in the worst cases, put the public at risk.
“I would like to see fines made proportionate to the turnover of the company and for the courts to apply these penalties consistently. Anything less is no deterrent.”