Defra has written to the Chief Executives of the UK water companies telling them that companies will need to introduce monitoring for the vast majority of their combined sewer overflows (CSOs) by 2020.

Defra has belatedly published the letter dated 18 July 2013 – which was also copied to the Environment Agency and Ofwat - from the former Water Minister Richard Benyon MP in response to a request the Department received under the Environmental Information Regulations 2004 (EIRs).

Mr Benyon told the CEOs that discharges from combined sewer overflows (CSOs) are “increasingly becoming a reputational issue for water companies in a way not dissimilar to leakage from supply a few years ago.”  He said:

“Whilst much has been done and considerable investment made to improve the performance of CSOs their management and operation remains a regular cause for concern for both water users and the wider public. “

The Minister acknowledged the key role played by CSOs in the management of combined sewerage systems, saying that they would continue to represent a legitimate safety valve when systems become overwhelmed by exceptional circumstances.

He added that a water company understanding where its CSO assets are and how they are performing is “a basic element of sound sewerage management. “

The frequency of discharges from many CSOs, particularly those to sensitive waters such as bathing or shellfish waters, is already monitored and many more are monitored to enhance the management of sewer systems.

Monitoring discharges can provide clear and consistent data to inform discussions around the performance of sewer systems with customers and other interested groups. Monitoring changes in the behaviour of CSOs allows potential issues to be addressed before there are adverse impacts on the environment.

Mr. Benyon explained that the need for appropriate monitoring is reflected in the Drainage Strategy Framework published in May and the benefits reiterated in the National Adaptation Programme published earlier this month. Monitoring the levels of discharges also makes an important contribution to ensuring that sewerage systems are compliant with relevant legislation.

Telling the CEOs he believed that water the companies need to introduce monitoring for the vast majority of their CSOs by 2020, Mr. Benyon said the Government felt the issue was sufficiently important that it now intended to include monitoring of CSOs in the water discharge permitting regime, commenting:

“Consistency, reliability and transparency are very important in respect of CSO monitoring, not only to individual companies but to the country’s collective position.”

He concluded:

“I understand that the industry is developing a long term approach, a road map, setting out how it intends to address the challenges presented by CSOs. This may cover a range of issues but key amongst them must be how any high frequency discharges will be appropriately addressed. There are a range of possible solutions available to water companies.”

“These are likely to have strong links to wider drainage planning allowing the most sustainable options to be identified. Each company should set out its own objectives and trajectory for dealing with high frequency CSO discharges, responding to existing monitoring data as well as that derived from the expansion of monitoring through to 2020.”

“…. I would welcome initial proposals from each company to be published at the same time you submit your business plans.”