Dwr Cymru Welsh Water

Welsh Water — serves 3 million people across most of Wales and parts of Herefordshire. Major rivers: Wye, Usk, Tawe, Teifi, Conwy. Regulated by Natural Resources Wales rather than the Environment Agency.

Dwr Cymru Welsh Water operates 2,359 monitored storm overflows. 11 are currently spilling. The data records a cumulative discharge of 3.8 years across this operator's network in the last 30 days across an estimated 12,548 events. The Truth Engine has 74 open flags for this operator's overflows right now.

📍 View on national map →📄 Download Truth Report (PDF)⬇ Overflows · CSV

2,359

Storm overflows

Active right now

Monitors offline

Open flags

3,137

Spills · last 7 days

3.8 years

Cumulative discharge · 30 days

1.5 h

Avg event length · 30 days

216

Spills · last 24 hours

Spill record· since 6 May 2026 · network-wide

65,497

spill events

69,652h

cumulative discharge

3 weeks

longest single event

2026-05-06

first event on record

Across 11 water companies in the EA dataset, Dwr Cymru Welsh Water averaged 14.1h per monitored overflow in the last 30 days. The national median was 3.9h per overflow. ranked 11 of 11 of UK water companies by 30-day spill hours per monitored overflow.

Most-discharged-into watercourses

The 12 watercourses with the most Dwr Cymru Welsh Water overflows discharging into them.

River Dee56 overflows
Afon Lwyd47 overflows
River Taff47 overflows
River Wye45 overflows· 1 active
River Cynon45 overflows
Unnamed Watercourse41 overflows· 1 active
River Ebbw39 overflows
River Teifi37 overflows· 1 active
River Rhymni37 overflows
Menai Strait36 overflows
River Tawe34 overflows
River Usk30 overflows

Dwr Cymru Welsh Water

Spill record· since 6 May 2026 · network-wide

Most-discharged-into watercourses

Currently spilling· 11

River Teifi

Afon Lledr

Gwendraeth Fawr

Afon Marlais

Nant Hafren

Elwy

River Twymyn

River Wye

Unnamed Watercourse

River Taf

Afon Camnant

Truth Engine flags against Dwr Cymru Welsh Water· 25 open