More stringent CSO rules announced

Both Ofwat and the Department for environment, food and rural affairs (Defra) have set out plans for more stringent expectations around combined sewer overflows (CSOs).

This includes a monitoring commitment from the regulator and Defra’s plan to include coastal areas in discharge reduction targets.

Ofwat said wastewater companies will face penalties for inadequately monitoring CSOs as it proposes targets to lower the average number of spills from overflows.

Any location where a monitor is faulty, Ofwat said it will assume that spills are twice as bad as the current average “to push companies to make sure monitors are working”.

Ofwat said targets will be consistent with the strategic priorities set by Defra and Welsh government.

For the next next asset management period (AMP8) from 2025, Ofwat proposed reduction targets based on each company’s current average spills per year. It will measure spills over 12 hours as more than one event, and any additional 24 hour period to count as another spill.

This will cover all spills – including those covered with discharge permits. The regulator said this would “incentivise companies to reduce spills over above any statutory obligations”.

The proposal is the “best option available” for PR24, Ofwat said. The upcoming price review will be the first to include a performance commitment relating to storm overflows as public, media and political attention has escalated interest in CSOs.

“Companies need to reduce the use of storm overflows. We want to introduce measures to hold them to account for this and to ensure companies are effectively monitoring their use of storm overflows,” Aileen Armstrong, senior director said.

“We will continue to use all the powers we have to drive companies to get to grips with this issue.”

The number of spills should, the proposal said, correlate to any environmental harm by reflecting duration.

It will consider alternative ways to measure performance at future price reviews as monitoring devices become more sophisticated and provide better data.

An unmonitored overflows adjustment has been proposed to require companies to assume CSOs with no, or faulty monitoring equipment discharge at double the average rate to incentivise adding event duration monitors. This approach, Ofwat said, risks overstating the level of spills but provides a strong incentive to consistently monitor performance.

Fines will apply for missing targets.

Separately, Defra said it will consult on adding coastal waters to discharge reductions. Last month through the Environment Act, reduction targets became enshrined in law.

These were criticised by environmental groups for focusing on fresh waters but not coastal areas. Good Law Project has been granted a three-day hearing in July to challenge Defra on this matter.

Now, government has said it will consult to expand the targets to cover all coastal and estuarine overflows.

Environment secretary Thérèse Coffey said: “As a coastal MP myself, I know that our coastlines are hugely important to local communities and to nature.  While 93% of our beaches with designated bathing status are already rated excellent or good, I intend to use my powers to better protect all of our coasts and estuaries”.

A date has not been announced for the consultation.