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Dwr Cymru Welsh Water

Welsh Water provides water supply and sewerage services to over three million people in Wales and some adjoining areas of England.

The company operates 81 reservoirs, 105 water treatment works and supplies an average 900 million litres of water every day through a network comprising 27,000km of water mains, 532 pumping stations and 715 service reservoirs. DCWW also collects wastewater (including surface water and highway drainage) through a network of 19,000km of sewers, 1,700 sewage pumping stations and 3,300 combined sewer overflows. Wastewater is treated at 832 treatment works.

Cardiff & Afan Wastewater Treatment Works (2024)

Optimisation of the combined heat and power (CHP) plant performance to increase electrical output at each site by between 2-3 GWh per year

Leominster WwTW (2024)

New tertiary nitrifying sand filter process stage with additional upgrade works on existing assets to achieve a high quality effluent

Llyn y Fan Fach Reservoir (2024)

Grade II listed structure that underwent refurbishment to address safety concerns in the draw-off tower and spillway

Queensferry WwTW (2024)

Replacement of existing inlet works with new DfMA structure

Rotherwas WwTW (2024)

Wastewater treatment upgrades for eutrophication mitigation and environmental compliance to remove phosphorus from the River Wye

Sluvad WTW (2024)

Removing manganese and iron through the first UK water industry application of jet mixing for coagulant mixing at a water treatment works

Lluest Wen Reservoir (2023)

Located near Maerdy in South Wales, Lluest Wen Reservoir is a Category A Large Raised Reservoir as defined by the Reservoirs Act 1975. The reservoir is impounded by a 200m long, 25m high earth embankment dam across the Rhondda Fach River and currently impounds 1.07Mm3 of water. Construction of the reservoir was originally completed in […]

Llyn Bran Discontinuance (2023)

Llyn Bran is located in Denbighshire, north-east Wales and was a natural lake that was raised in 1899 by a concrete dam. The reservoir was used to supply water to the North Wales Hospital in Denbigh. The hospital closed in 1995 and Llyn Bran has not been used for drinking water since. As part of […]

Norton, Presteigne & Weobley WwTWs (2023)

The Rivers Lugg and Wye have been identified as having high levels of phosphorus, which is causing eutrophication of these watercourses. Norton Wastewater Treatment Works (WwTW) discharges treated final effluent to the Norton Brook, a tributary of the River Lugg. Presteigne WwTW discharges treated final effluent directly into the River Lugg downstream of the Norton […]

Usk Reservoir (2023)

Usk is a large raised reservoir formed by an earth embankment dam, which completed constructed in 1955 with an approximate capacity of 12,268,000m3. The dam is 480m in length, with a maximum height of 31m, and supplies raw water to Bryngwyn Water Treatment Works and as well as providing compensation water to the River Usk, […]

Cardiff Western District SPS (2022)

Cardiff Western District Sewage Pumping Station (CWD SPS) receives sewage from the western area of Cardiff for onward pumping to Cog Moors WwTW via twin rising mains. The pumping station is a strategic asset and is operationally critical to Welsh Water. Failure of this asset would have severe business impacts. During AMP6, a root cause […]

Pant-Yr-Eos Reservoir (2022)

Pant-yr-Eos is a large raised reservoir situated approximately 2km east of Risca in the City of Newport, Monmouthshire. It is impounded by a 27m high, 280m long embankment dam with clay core, and has a storage capacity of approximately 600 Ml. The reservoir was completed in 1878 for provision of water supplies to Newport. To […]

Plas Uchaf Reservoir (2022)

The construction of Plas Uchaf Reservoir was completed in 1870. It has an embankment dam that is approximately 15m high, with a puddle clay core. It has a retained capacity of 225,500m3 and a surface area of 3.5ha. The reservoir is formed across a tributary of the River Elwy, with Dolwen Reservoir located approximately 0.7km upstream of Plas […]

Welsh Water Dynamic Water Quality Assessment (2022)

The River Gwili and River Gwendraeth Fawr in Wales have long suffered from poor water quality, often failing to meet phosphate targets. It was believed that the discharges from seven wastewater treatment works were contributing to deterioration in these two rivers. The need to improve the river water quality was established, but the means to […]

Ynys-y-Fro Lower Reservoir (2022)

The Ynys-y-Fro Reservoir system is situated 1km north-east of High Cross, Newport. The system comprises two reservoirs in cascade: an upper ‘subsiding’ reservoir and a lower ‘old pond’ reservoir. The upper reservoir is immediately upstream of the lower reservoir. The lower reservoir was constructed as an earth embankment dam and was built for the supply […]

Cog Moors Advanced Anaerobic Digestion Facility (2021)

Welsh Water’s sludge strategy is to treat 97% of sludge using advanced anaerobic digestion (AAD) technology. The Cog Moors AAD facility was constructed to supplement the existing facilities at Cardiff and Afan in South Wales along with the recently constructed Five Fords facility in North Wales. AAD gives the benefits of: Meeting the Enhanced Sludge […]

Dolwen Reservoir (2021)

Dolwen Reservoir is a Category A Large Raised Reservoir as defined under the Reservoirs Act 1975. It is located on a tributary of the River Elwy, 0.7km upstream and north of Plas Uchaf Reservoir, near Abergele, Conwy, Wales. It was constructed in 1905 and has a capacity of approximately 288,185m3. Dŵr Cymru Welsh Water commissioned […]

Lletty Brongu & Ruthin STWs (2021)

Welsh Water raised a programme of quality schemes for completion in AMP6 to address tightening of phosphorus permits set by Natural Resources Wales (NRW) at ten wastewater treatment works. Some of the sites in the programme were subject to a new total phosphorus (TP) permit of 0.5 mg/l T-P and required the installation of a […]

Lower Neuadd Reservoir (2021)

Lower Neuadd Reservoir is located in the Brecon Beacons, 5km north of Merthyr Tydfil in south Wales. The reservoir, which is an embankment dam, was constructed in 1884. It is the middle of a cascade of three reservoirs, with Upper Neuadd situated 3km upstream of the much larger Pontsticill Reservoir. Lower Neuadd Reservoir had a […]

Maerdy WTW (2021)

Maerdy Water Treatment Works (WTW) is located 35km north of Cardiff, supplying up to 16Ml/d potable water to customers in Ferndale and the surrounding area. Raw water is gravity fed from Castell Nos and Lluest-Wen Reservoirs and the quality can be highly variable, particularly following heavy rainfall resulting in a challenge to WTW performance. In […]

Bewdley Bank Service Reservoir (2020)

The Hereford Water Network is dependent on a single source of supply from the River Wye and Dŵr Cymru Welsh Water identified a need to assess the resilience of the network to maintain customer supply during any future loss of source supply events. The resulting hydraulic assessment identified the requirement to increase the available storage […]

Llyn Brenig Reservoir (2020)

Llyn Brenig impounding reservoir is located in the Denbigh Moors in North Wales. It was constructed in 1975 and was officially opened by the Prince of Wales. It forms part of the River Dee regulation to manage flow into the Dee via the Afon Alwen. The reservoir has a capacity of around 60 million cubic […]

Northumberland & Halfway SPS (2020)

Llanelli Wastewater Treatment Works (WwTW) in Llanelli, South Wales, serves the catchment’s 60,000 inhabitants and discharges treated effluent into the Loughor Estuary. The estuary is not only ecologically sensitive, but also a critical natural asset to the local community and to the wider South Wales region. It is a natural capital asset, home to commercial […]

Bryn Cowlyd WTW (2019)

Bryn Cowlyd Water Treatment Works is located south of the village of Dolgarrog in county of Conwy. The works is gravity fed with raw water from Llyn Cowlyd, 350m above and approximately three miles south west of the works, in the Carneddau mountain range in Snowdonia National Park. The old treatment works was commissioned in […]

Garreglwyd Raw Water Supply Main (2019)

Dŵr Cymru Welsh Water has an extensive network of rural water supply assets in North Wales, with numerous service reservoirs and many kilometers of pipeline. Emergency repairs or mitigation measures have arisen from both freeze-thaw conditions and dry weather over the past few years. During 2018 there were both extremes of cold weather and one […]

Talybont Reservoir (2019)

Talybont is a Large raised reservoir situated in the Brecon Beacons National Park approximately 30 miles north of two of the most populated cities in Wales; namely Cardiff and Newport. Construction of Talybont Dam began in 1932 and ran through until 1939. It was conceived out of a requirement to supply treated water to the […]

DCWW AMP6 Water Quality Zone Improvements (2018)

Of Dŵr Cymru Welsh Water’s 85 (No.) Water Quality Zones (WQZs), 20 (No.) contribute 75% of the company’s targets to improve water quality and reliability. Detailed analysis has been carried out and documented in Zonal Study reports for these zones. These identified specific schemes, ranked in cost benefit order, presented in a standard plan and […]

Glascoed WTW (2018)

Welsh Water’s Glascoed Water Treatment Works (WTW) is situated south of the village of Bodelwyddan in the county of Denbighshire. It was commissioned in 1994, with additions made in 1995 and 2009. The works supplies up to 20 Ml/d to customers along the North Wales coast. The works receives its supply of raw water from […]

Llanfaethlu WwTW (2018)

Llanfaethlu Wastewater Treatment Works (WwTW) is situated to the north east of the village in Anglesey, North Wales and is owned and operated by Welsh Water. Constructed in the 1960s as a conventional gravitational treatment works, the process utilises primary settlement, stone media trickling filter and humus settlement discharging to a grass plot, together with […]

Newport East (Nash) Wind Turbine (2018)

Welsh Water is committed to reducing its carbon footprint and protecting the environment from the effects of climate change and is pursuing measures to generate more of its own power from renewable sources. Welsh Water recently signed a five-year contract with Dong Energy to supply green energy to power its sites, as well as introducing […]

North Wales Sludge Strategy & Five Fords AAD (2018)

Welsh Water set out its vision in its Sewage Sludge Strategy 2040 how it intended to deal with the number one waste management challenge all water utility providers face, the sustainable management and disposal of wastewater sludges. With ever tightening nutrient and heavy metal limits on agricultural usage, and more pressure than ever for companies […]

Prioress Mill Raw Water Pumping Station (2018)

Prioress Mill Raw Water Pumping station (RWPS) is located in Rhadyr, near Llancayo, Monmouthshire, on the south bank of the River Usk. It abstracts at a rate of up to 318 ML/day, and is the primary supply to Llandegfedd reservoir, which then feeds Sluvad Water Treatment Works (WTW). Prioress Mill RWPS has been identified by […]

Tynywaun WTW (2018)

Tynywaun Water Treatment Works forms part of the South East Wales Conjunctive Use System (SEWCUS) chain of water treatment works that supply the central South Wales valleys and cities of Newport and Cardiff. This SEWCUS system does not, however, provide full conjunctive use to the Tynywaun distribution area, having very limited connectivity. The works has […]

Usk Spillway Upgrade (2018)

Usk Reservoir in Brecon is situated south east of Llandovery and approximately 5km to the west of Sennybridge. The reservoir is an existing 12.3Mm3 reservoir in the Brecon Beacons National Park in South Wales. It is impounded by a 31m high, 480m long embankment dam with a clay core, which was constructed in 1955. The […]

Bynea Sewage Pumping Station (2017)

Dŵr Cymru Welsh Water (DCWW) is carrying out a strategic package of works in the Llanelli and Gowerton catchments with the aim of reducing spills into the Loughor Estuary. Bynea Sewage Pumping Station (SPS) is a key asset, receiving sewage flows from the local catchment and transferring them to Llanelli WwTW. The site originally operated […]

Cambrian RainScape (2017)

The Cambrian catchment has a population of 4,500 and is located in Llanelli, South Wales. The catchment is predominantly served by combined sewers with a combined sewer overflow (CSO) at Cambrian Sewage Pumping Station (SPS). The CSO discharges approximately 52 times per year (54,000m3 per year) into the Loughor Estuary, a designated Shellfish Water. The […]

DCWW Coastal Investigations Programme (2017)

In March 2015 Dŵr Cymru Welsh Water (DCWW) launched the biggest Welsh coastal investigation and modelling project ever undertaken to enhance its understanding of the factors affecting water quality at 49 sites (29 bathing waters and 20 shellfish waters) along the entire Welsh coastline. The evidence gathered from this study will allow DCWW to assess […]

DCWW Wastewater Treatment Works Rationalisation (2017)

While the investment by the regulated water sector of England and Wales is governed by a five-yearly cycle, this investment relates to what are long-lived assets. Decisions about when to undertake capital investment and what to include in a capital programme have a direct bearing on the operating costs associated with the assets. Ultimately the […]

Llyn Teifi Spillway Rehabilitation Works (2017)

Llyn Teifi Reservoir is situated in a remote area on the western slopes of the Cambrian Mountains in Ceredigion, west Wales, and was created in the early 1960s by raising a natural lake. It is impounded behind six embankments constructed across natural low spots along its south-western margin, covering an area of just over 25 […]

Swansea Bay WwTW Wind Turbine (2017)

Dŵr Cymru Welsh Water (DCWW) is investing in technologies to generate electricity on its sites in order to reduce their carbon footprint and the amount of imported energy. DCWW has already implemented technologies including solar photovoltaic panels, hydro turbines and gas-to-grid; however the new wind turbine at Swansea is their first wind generation site. Swansea […]

Tynywaun WTW (2017)

Tynywaun WTW is located at the north end of the Rhondda Fawr Valley, at the base of the Rhigos Mountain, in the village of Tynewydd at an elevation of 1,000 feet. Water treatment works have operated at the Tynywaun site since 1906 and the existing works was last refurbished during the 1990s, with new filters […]

Bryn Cowlyd WTW (2016)

Welsh Water’s Bryn Cowlyd Water Treatment Works (WTW) is located near Dolgarrog village in the Conwy Valley. The site sits on the eastern side of the Carneddau mountain range on the outskirts of Snowdonia National Park. The existing works on the site was commissioned in 1998 and can deliver up to 46Ml/d of clean water […]

Five Fords WwTW (2016)

Five Fords WwTW is a sewage works just outside Wrexham in north-east Wales blending passive and activated sludge treatment. The works is named because there are five fords crossing the River Clywedog (Afon Clywedog) locally. The works covers a large area of land and is neighbour to fields leased to local farmers. The sewage treatment […]

Pontsticill Reservoir (2016)

Located in the Brecon Beacons on the outskirts of Merthyr Tydfil, Pontsticill Reservoir and treatment works date from 1927. The Reservoir holds approximately 13.6 gigalitres of water and is a key element in the supply of drinking water to 106,000 customers in this region of South wales. In recent times Dŵr Cymru Welsh Water has sought […]

Upper Neuadd Dam Stability (2016)

Upper Neuadd Dam is a Grade II* listed structure, situated in the heart of the Brecon Beacons below Pen y Fan in the Taf Fechan valley, about 13km north of Merthyr Tydfil. It is owned and operated by Dŵr Cymru Welsh Water and is the upper dam in a cascade including Lower Neuadd and Pontsticill […]

Llyn Conwy WTW (2015)

New treatment works in the Go to Green programme using a single filtration stage with sand and Polarite media to reduce manganese levels

Phosphorus Removal Scheme (2015)

Phosphorus removal to meet new environmental consent concentrations for final effluent discharges into Carmarthen Bay

Alltwen-Pontardawe Combined Sewer River Crossing (2014)

A collaborative approach to find an innovative solution for a new combined sewer river crossing to reduce CSO pollution and property flooding

Blackmill Rainscape Strategy Scheme (2014)

Preventing a poor performing CSO asset from spilling with surface water removal schemes and network enhancements

Chester Brick Sewer Rehabilitation (2014)

Replacement of approximately 100m of 1,240mm diameter Victorian brick sewer in Chester, working in live flows

Glyncoed Terrace FAS (2014)

Integrated catchment planning & smart assets to deliver a sustainable & affordable flood risk management scheme

Llanelli - Retro Fit Green Infrastructure (2014)

Implementing the UK’s first large scale retrofit green infrastructure strategy providing sustainable flood risk management and pollution reduction

Saltney & Kinmel Bay Rising Main Replacements (2014)

Securing long term operational performance and preventing pollution

Singleton Park (Swansea) 5 CSOs Scheme (2014)

Addressing the unsatisfactory intermittent discharges from five CSOs as part of the Swansea Bay Strategy

Swansea Bay WwTW (2014)

MBBR and DAF solution: an innovative process solution to enhance performance for Dŵr Cymru Welsh Water

Beachley Sewerage Scheme (2013)

Provision of a new public sewerage system for 110 properties

Begelly & Kilgetty FAS (2013)

Reduce the risk of localised flooding of properties within the Langdon catchment

Briton Ferry FAS (2013)

Flood protection provided through a stormwater separation solution

Coed Dolwyd Service Reservoir (2013)

£9m investment offers security of supply and storage to 70,000 customers in North Wales

Gowerton WwTW - Sea Outfall (2013)

Outfall rehabilitation to alleviate pollution in a SSSI and designated shellfish water

Hartridge UID Scheme (2013)

Sustainable solution to address aesthetic pollution to a local watercourse and Newport Gwent Levels from two CSOs

Heswall WwTW - Shellfish Waters (2013)

£6.8m underground storage tank to improve performance & reduce the number of spills into the Dee Estuary

Lampeter STW (2013)

Critical refurbishments needed to improve the quality of the final outlet

River Rangers (2013)

Dŵr Cymru Welsh Water launches a strategy to identify and reduce sewer pollution

Specification for SuDS (2013)

Developing and implementing a sustainable drainage planning framework for Dŵr Cymru Welsh Water

Alwen WTW (2012)

£14m investment to improve disinfection processes and aluminium removal performance

Burry Inlet Investigations (2012)

Retrofit SuDS used to reduce CSO spills into protected shellfish water

Capel Dewi WTW (2012)

Treatment works extension and existing works improvements

Carmarthen Wastewater Improvement Scheme (2012)

Dŵr Cymru Welsh Water resolve pollution and sewer collapses in Historic Carmarthen

Five Fords WwTW (2012)

New anaerobic digestion plant and habitat quality upgrade

Flood Alleviation Works for Critical Infrastructure (2012)

Works at four assets in Wales identified as being ‘at risk’ from flooding

Flood Consequence Assessments of Critical Assets (2012)

Dŵr Cymru Welsh Water’s assessments of eight infrastructure assets in Wales

Langdon Road Sewage Pumping Station (2012)

Dŵr Cymru Welsh Water refurbishes a critical asset to improve bathing water quality in Swansea Bay

Newport Parrog Long Sea Outfall (2012)

New long sea outfall to improve bathing water quality on key Pembrokeshire beach

Trelawney Ave Flood Alleviation Project (2012)

Using cost-effective solutions and sustainable technologies to reduce the risk of flooding

Cardiff & Afan AAD Plants (2011)

Dŵr Cymru Welsh Water delivers AD plants early, and moves towards power self-sufficiency in wastewater treatment

Crai WTW (2011)

Upgrade with CoCoDAFF® and existing works refurbishment

Mynydd Llandygai WTW (2011)

Integration of a new counter current dissolved floatation and filtration (CoCoDaff) process into an existing works

Whitchurch WwTW (2011)

Programme of improvements to meet new EA consent and habitats drivers

Cardiff East Control Strategy (2010)

Cardiff East control strategy to low lying flood areas

Cog Moors STW - Storm UV Disinfection (2010)

Sustainability through new technology and seasonal consenting

Cwellyn WTW (2010)

Enhancement with DAF, RGF and Ultraviolet Disinfection

Llanbedr, Barmouth, Fairbourne & Nefyn WwTWs (2010)

Programme to improve MBR performance in North Wales

Northumberland Avenue SPS (2010)

3-channel medium pressure UV disinfection plant

Amlwch WwTW (2009)

£7 million investment at new WTW in North Wales

Cog Moors STW - Storm UV Disinfection (2009)

An innovative use of UV technology to achieve bathing water compliance

Lower Carno Dam Remediation (2009)

B&V demonstrates the effectiveness of a fully integrated consulting and construction business

Penybont WTW (2009)

WTW upgrade with steel tank dissolved air flotation and rapid gravity filtration

Steynton (Merlins Bridge) Pumping Station (2009)

Careful planning and commitment lead to success

Bretton WTW (2008)

Combined quality and capital maintenance project

Chester WwTW (2008)

Storm tank discharge and inlet works

Crynant WwTW (2008)

Largest biological contactor & reed bed in Wales installed

Ystradyfodwg & Pontypridd - Wedal Road Truck Sewer Duplication (2008)

Trunk sewer duplication - new 250m inverted siphon sewer

Cross Hands WwTW (2007)

£3m expansion to accommodate food park

Eign WwTW (2007)

High rate filter replacement

Morfa Bychan WwTW (2007)

New wastewater treatment works on site of existing headworks

Glan Usk River Work (2006)

Remedial works to slope damage

Merthyr Dyfan Wastewater Storage Tank (2006)

An innovative semi-precast concrete solution

Plumbosolvency (2006)

“Plumbo” scheme - excellent example of successful alliancing

Rhymney Valley Sewer (2006)

Enhanced productivity tools optimise sewerage improvements

Trefor WwTW (2006)

New £1.2 million WwTW

Gowerton WwTW (2005)

Upgrade work to meet consents

Harlech & Llanbedr WwTWs (2005)

“Greenfield” WwTW schemes for coastal communities

Huxley Green UIDs (2005)

Eliminating UID problem & reducing local flooding

South-Mid Ceredigion Water Supply (2005)

Curing shortfall now & catering for predicted 25 years growth

Cardigan Catchment Solution (2004)

Part of Welsh Water’s £1.2 billion investment programme

Five Fords WwTW (2004)

Whole catchment solutions challenge the norm

Gelligaled Solar Powered CSO (2004)

First solar powered combined sewer overflow - UK ‘first’ claim for Gelligaled Park, South Wales

Holyhead WwTW (2004)

Full SBR treatment & environmental benefits to area

Water Mains Rehabilitation (Welsh Water) (2004)

Dwr Cymru Welsh Water on track to beat this target

Crai Water Supply Refurbishment Project (2003)

Major rehabilitation of supply network in Swansea Valley

Llandudno Sewage Flooding Prevention Scheme (2003)

Dwr Cymru Welsh Water’s biggest flood protection project

Llangefni WwTW (2003)

New Biological Nutrient Removal Scheme (BNR) for 30,000 PE

Llangrannog WwTW (2003)

£1.3m investment at Cardigan Coast village

Pontsticill WTW (2003)

Solving concrete corrosion problem at DAF plant

Porthcawl CSOs (2003)

£5.8m investment cleans up the sea at popular resort

Broomy Hill WTW (2002)

Extensive upgrade provides essentially new asset

Caerphilly Water Mains Rehabilitation (2002)

Water mains rehabilitation DCWW Wales & Hereford Region

Colwyn Bay CSO Improvement Scheme (2002)

Combined surface water and CSO improvement scheme

Garnswilt WwTW (2002)

Combined sewer overflows & waste water treatment works

Prestatyn & Llanasa WwTW (2002)

New WwTW in constrained site will serve two catchments