Water industry regulator Ofwat has published the results of an independent report on sewerage planning and drainage area plans by water and sewerage companies in England and Wales.

The regulator commissioned the report in order to understand what the industry is doing now to deliver economical and effective long term drainage management and how well it does it. Ofwat also wants to understand how sewerage planning tools are used by companies, both in planning for the long term and on a business as usual basis.

 Ofwat said that in order to move forward on managing demand by using more natural drainage processes, it wanted to ensure that the regulatory framework provides the right incentives for, or at least does not present barriers to companies to consider different long term approaches.

 The report was based on structured interviews with all ten water and sewerage companies in England and Wales. In addition, meetings with Defra and the Environment Agency were held to elicit the views of both organisations on current and future practices to support a sustainable drainage industry.

 Introducing the report, the Review of sewerage planning and drainage area plans, Ofwat said that in the future, particularly as climate change increases the intensity of rainstorms, the capacity of current drainage systems will be insufficient to meet the demands placed on them.

The objectives of the report were to:

• understand what processes, systems and tools companies have to support robust long term sustainable planning.

• highlight good practice.

• clearly articulate the approaches and common themes across the industry to a wide range of stakeholders.

• identify improvements that could be made to incentivise:

i. proactive management of the sewerage system to prevent failure occurring

ii. robust decision making to ensure that developments are located in the most sustainable way

ii. greater understanding of drainage systems which will be required if companies are to implement demand reduction rather than increasing capacity.

Robust processes already in place

In general, the report concludes that companies have robust processes in place to understand their sewerage systems, although the processes and terminology vary between companies. They are also moving towards a more holistic view of the sewerage system taking into account structural, operational and hydraulic analysis of the network with variable degrees of integration.

However, the report noted that the degree to which sewerage planning tools are used to support the development of long term sustainable solutions is variable.

Sewerage planning used by all companies to support investment planning process

The report concludes that the information obtained through sewerage planning is used by all companies to support their investment planning process. However, the degree to which sewerage planning tools are used to support the development of long term sustainable solutions is variable

Generally companies use separate planning tools for sewage treatment and sewer networks, although some companies are evaluating investment needs in an integrated approach.

The review considered the way in which the outputs of the sewerage planning process are used by companies both internally and externally. Key internal uses are capital and operational maintenance planning and for defining wastewater supply-demand investment.

In some cases systems based on current or live data are used for planning operational maintenance activities such as jetting. Other company systems for capital maintenance planning, such as sewer rehabilitation, may be integrated with the sewerage planning process or informed by it. The report says the main issue faced by companies is the uncertainty of planned development.

Findings will help regulator to develop right incentives

Ofwat said the report had helped to articulate the planning that companies already do. It now plans to build on this and ensure the regulatory framework produces the right incentives on the companies to make sustainable choices. This will be implemented  through Ofwat’s interlinked ‘future regulation’ programme of projects. The best practice identified in the report will also be used by water companies to help them improve the way they carry out sewerage planning.