Welsh Water lodges plans for £600m record infrastructure job

Welsh Water has submitted planning applications for a £600m overhaul of water treatment infrastructure serving more than 400,000 properties across south Wales. The Cwm Taf scheme is the biggest infrastructure project in the company's history, replacing treatment assets that have served the region for more than a century.

Contractors and investors are already being sounded out ahead of procurement starting in early 2027. The competition will run under Ofwat's Direct Procurement for Customers model, which Welsh Water will deliver through a competitively appointed provider on a 25-year contract.

What does the planning submission cover?

The main construction package centres on a new water treatment works at Dan-y-Castell Farm near Merthyr Tydfil, together with treated water storage, a new pumping station at Pontsticill and connecting pipelines.

A second project will upgrade Llwyn-onn Water Treatment Works in the Bannau Brycheiniog National Park, adding water storage and pipeline connections.

Together, the two projects will allow the existing Pontsticill and Cantref treatment works to be retired as maintenance becomes increasingly difficult and costly.

Planning applications have gone to Merthyr Tydfil County Borough Council and Bannau Brycheiniog National Park Authority.

What is the delivery timetable?

Earlier market engagement outlined a 25-year contract for a competitively appointed provider, with a delivery partner appointment targeted for August 2028. That timetable envisaged regulatory completion in March 2032, followed by 12 months of testing.

The latest announcement values the investment at £600m, down from the £667m figure used at the earlier market engagement stage. The reduction is the number bidders will scrutinise as procurement approaches.

For supply chain firms, the immediate date is 10 November, when Welsh Water hosts a major engagement event at ICC Wales in Newport to explore work opportunities with delivery partners and the wider supply chain.

Why is Welsh Water acting now?

Welsh Water chief executive Roch Cheroux said: "As a company we need to deliver this critically important infrastructure for the benefit of our customers. The effects of climate change are already being realised in Wales, with extreme weather bringing more frequent storms and heatwaves, all increasing the pressure on our ageing water treatment assets."

The revised plans follow community consultation and include:

• Green roofs on new structures
• Habitat improvements around the sites
• Greater use of previously developed land at existing sites

The green roofs and habitat commitments matter for practitioners: both planning authorities — one a national park authority — will weigh landscape impact heavily, and the design changes signal how Welsh Water expects to clear that hurdle.

With procurement eighteen months away and a delivery partner targeted for August 2028, contractors wanting a share of the largest job Welsh Water has ever tendered should treat the Newport event as the entry point.