Improving drainage and sewage systems

We are developing a long-term plan for our drainage and wastewater services, in line with our Welsh Water 2050 Vision to become a world-class, resilient and sustainable service for the benefit of future generations.

This plan will set out how we intend to extend, improve and maintain drainage and wastewater systems across Wales.

This is a new framework for drainage and wastewater management which will consider how the foul water and surface water is currently managed, helping to provide us with information to manage our wastewater systems over the next 25 years.


  • More meaningful consultation with customers, regulators, developers and other stakeholders on wastewater and drainage planning
  • We will work with our regulators and other wastewater companies to ensure greater transparency of our plans
  • Insight into predicted future trends in our wastewater services
  • Opportunities for collaborative solutions to flooding and environmental problems
  • Value-for-money investment plans that are updated on a five-year rolling cycle

Drainage Responsibilities

Drainage and wastewater systems cover a variety of drainage assets and infrastructure, including different owners and responsibilities.

Involving you

We want to involve our customers and stakeholders in the development of the Drainage and Wastewater Management Plan. Once we have developed some draft plans, we will be consulting on our proposals. We will provide further information on the proposals in due course. In the meantime, if you have any queries, please click here.

Our Drainage and Wastewater Plans

What’s the problem?

We will be looking at a range of different problems which can and do affect our drainage and sewage systems, as well as considering how these might change in the future, and how we can continue to meet and exceed our customers’ expectations. Some of these areas for consideration include:

  • Managing assets: Where drainage systems discharge into water bodies, where are the risk areas in terms of sewer blockages, collapses or pollution incidents?
  • Receiving water quality: Ensuring that wastewater is treated to the standards required by our regulators in order to meet the needs of the local environment.
  • Flood risk management: How do we manage our networks to prevent sewer flooding when there are significant storm waters entering our systems?
  • Climate change: What do we need to do to offset the impacts of climate change?
  • Growth: What are the plans for growth in the area? How can we ensure that this growth does not put too much pressure on drainage and wastewater systems?

Local, regional and strategic planning

We will be developing one overarching plan that will consider planning at the Welsh Water operational level, at regional drainage basin levels, and at more localised tactical planning units. Using these levels, we will be able to consider more specific impacts on water quality and flood risk management, as well as how this relates to local or regional plans in that area and the specific needs of the customers we serve.

Our plan will cover the key issues across the Welsh Water operating area. At a company level, this will provide a strategic, long-term plan to provide a resilient drainage and wastewater service over the period of the plan.

At the drainage basin level, there are 13 distinct regions across Wales (these are aligned to the River Basin Management Plan areas). At this level, we will be able to understand and develop solutions to address regional issues that impact the quality of our streams and rivers or the risk of flooding.

Within the drainage basin level, there are more localised tactical planning units which are based on our treatment geography and watersheds. These will form the basis of our plan, and help us to ensure that we understand risks and solutions at the local level required to guarantee our wastewater treatment works and their catchments deliver a high standard of service.

If you would like any more information on our plan specific to any of the areas, you can contact us by emailing

How Do We Manage Wastewater?

Our sewerage systems collect domestic wastewater from drainage outlets around your home and carry it through a network of underground pipes to our treatment works. Here the effluent is cleaned and returned to the environment.

Where does wastewater come from?

Wastewater comes from toilets, sinks, baths, washing machines, and as a by-product of some industrial processes. Untreated, wastewater can be a significant pollutant that can kill fish, affect biodiversity, create a risk to human health and have an impact on the amenity value of land. It can also impact on the quality of rivers and bathing waters.

How is it treated?

In order to reduce the polluting effects of wastewater, we collect it and safely carry it through pipes to our wastewater treatment works. Here, the wastewater is treated to the standards required by our regulators in order to meet the needs of the local environment.

The first stage of treatment involves filtering out large particulates such a grit and other debris. After this, the wastewater is held to allow the waste particles to settle out in the form of a sludge. This separates the wastewater into a liquid part and a sludge part. The liquid part undergoes further treatment that again causes the particulates to settle out and generate sludge, whilst the polluting element of the liquid is treated, often by biological processes.

The final stages of treatment sees any remaining fine particulates removed from wastewater which may, dependant on local circumstances, undergo ultra-violet disinfection before the now clean water is returned to the local environment.

At each stage, the sludge is removed and treated separately and used for other purposes such as a source of energy or as a soil conditioner in agriculture.

Next Steps

We are currently in the early stages of developing our Drainage and Wastewater Management Plan. We will develop our plan in line with best practice, such as that set out in the industry framework developed on behalf of Water UK. The process of developing our plan includes an assessment of existing and future risk, characterising the problems we face, and developing options and solutions to address them.

We will be engaging with our stakeholders throughout each of these stages to ensure that we are working collaboratively on drainage and wastewater to understand the pertinent issues and develop sustainable solutions.

We will hold a public consultation for our draft plan, currently anticipated for 2022. This will be an opportunity for all to formally provide comment and we would welcome your views on and inputs to our proposed plan.