The new Strategic Policy Statement (SPS), which will be set by the government and formally laid in parliament this afternoon, will stress the importance of protecting the environment for the water sector’s economic regulator.

It will set out the government’s expectation that Ofwat and water companies will prioritise action to protect and enhance the environment, and deliver a resilient and sustainable water supply.

the government also says that it confirms new expectations that water companies must significantly reduce the frequency and volume of sewage discharges from storm overflows. It also urges Ofwat to challenge them to show how they will be more ambitious in protecting the environment, whilst also getting the basics right.

• Last year the Environment Agency concluded seven prosecutions against companies with fines of more than £100 million. The Agency has also launched an investigation into possible unauthorised spills at sewage treatment works.

Environment minister Rebecca Pow said: “Water quality is an absolute priority. We are the first government to set a clear expectation that Ofwat should prioritise action by water companies to protect the environment and deliver the improvements that we all want to see. I have been very clear of my expectations of water companies and where they do not step up we will take robust action.

“The priorities that we are setting out today build on the work that we have already undertaken to reduce harm from storm overflows, improve monitoring and reporting of pollution incidents making this more transparent, to tackle run-off from agriculture, and protect the health of our rivers and seas.”

A motion later passed which imposed a duty on water companies to reduce sewage discharges as a result of storm overflows, and will legally required firm to evidence a reduction in overspills over the coming five years.