Cwm Taf Water Supply Strategy

At Welsh Water, one of our main priorities is to provide customers with a first-class supply of drinking water direct to their taps.

To achieve this, we need to invest in new and resilient water treatment works and associated facilities which will provide our customers with a safe, reliable supply of clean drinking water for decades to come.

Water supply is tightly monitored and regulated by the Drinking Water Inspectorate (DWI). This ensures we supply water that is safe to drink and meets the standards set out in the Water Quality Regulations. Welsh Water was issued with a legal notice in 2019 by the DWI requiring us to provide new and improved water treatment processes in the area by March 2030.

Without major investment we will not be able to continue to meet the high drinking standards we must comply with and customers will be at risk of increased supply interruptions in the future.

Our emerging proposals

We are developing a plan to build new water treatment works, and associated facilities, to replace our existing works at Llwyn Onn, Cantref and Pontsticill which are nearing the end of their operational lives. The proposed facilities include:

  • New water treatment works facilities near Merthyr Tydfil, including enhanced water storage.
  • New raw water pipelines to carry water from existing reservoirs in the Bannau Brycheiniog National Park to the new water treatment works.
  • New treated water pipelines to carry treated water from the new water treatment works to the existing network and on to customers.
  • New and upgraded pumping stations to boost water pressures and ensure water can reach our customers.

The new facilities will not only provide new and improved water treatment processes but will also provide enough water storage to cater for future population growth and make it more resilient to the effects of climate change.

The project will ensure we continue to provide a first-class supply to customers every time they turn on their taps.

What we have proposed to date

In 2022 we consulted on early proposals with the local community to build a single new water treatment works near Pontsarn, to replace the three nearby water treatment works. We asked people to provide us with feedback on our initial plans and we would like to thank those that took the opportunity to do so. The feedback received was extremely useful.

In March 2023, we sent an update letter to customers in the Merthyr Tydfil area to explain that we took the decision to take some extra time to ensure full consideration is given to balance the local community’s feedback together with our need to build new water infrastructure before our plans are finalised. A copy of the letter can be viewed here.

What is happening now?

One of the key themes from the feedback to our consultation was whether other options were available, such as upgrading existing sites or an alternative location for the new Water Treatment Works. Other feedback included whether we could reduce the visual impact of the proposed water treatment works and also a desire to protect Merthyr Tydfil’s green infrastructure and heritage park – Cyfarthfa Castle.

Over the past few months we have been continuing to review our original proposal, taking into consideration the feedback received, exploring further possible options as well as conducting further surveys.

We have written to customers in the Merthyr Tydfil area with an update on progress made with the review and explaining some of the options we are currently looking at. A copy of the update can be found here.

We are still working hard to look at all the options to deliver an affordable solution to provide customers with fresh, clean drinking water for decades to come and aim to provide a further update in March 2024 once the current review has been completed and we have some clear options to present.

Please be assured that we will undertake a full statutory consultation process with the local community before any planning application is submitted.

Protecting the Environment

We take our responsibility for protecting the environment seriously, that is why we are continuing to carry out a number of surveys and ground investigations. These surveys include ecological and archaeological ones so that we fully understand the characteristics of the areas proposed for the work. and trying wherever possible to minimise environmental impact.

We’re also taking great care to ensure that our plans consider the visual appearance of how the buildings look and sit within the landscape.

Further information

We appreciate that there will be lots of questions about this project and why we need to do it.

Following our non-statutory consultation in March 2022, we produced a Frequently Asked Questions document which answers the most common questions people asked us. A copy of this document can be viewed here.

We will continue to review the questions we receive and update our responses in the frequently asked questions section below. We hope you will find this useful.

Should you have any queries then please email us


Customer Letter Cwm Taf Project March 2023

131.3kB, PDF

Customer Cover Letter November 23 Update bilingual

166.3kB, PDF

Customer Update Nov 23 Cwm Taf Newsletter bilingual

216.1kB, PDF

Cwm Taf Non Statutory Consultation FAQ (2022)

214.6kB, PDF