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Rhondda and Ogmore

Polluted by sewage 4,752 times in 2025 lasting 29,573 hours - That's 3.42 years!

Monitoring fell below 50% in some locations so could be more

© OpenStreetMap contributors
Contains OS Data © Crown copyright & database right 2021-2024
© Top of the Poops 2021-2024

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Live data for Rhondda and Ogmore in 2026

So far this year (as of 18 May 2026, 12:00) there has been 13,473 hours of sewage overflows, from 113 CSO Combined Sewage Overflow - a device that, when operating, pours combined rainwater & sewage into a waterway s - that's 1.56 years!

Totals for Rhondda and Ogmore in 2025

94 Sites polluted by Dwr Cymru Welsh Water
4,752 sewage dumps
29,573 hours duration
That's 3.42 years. On average 13 times a day

Change Over Time

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Waterways in Rhondda and Ogmore

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Pollution Summary 2025

Here are all the reported sewage overflow totals for Rhondda and Ogmore in 2025. Sometimes sewage can be being dumped for months at a time.

Reporting refers to how much of the time the monitoring was active. In this constituency 1 of the total 101 CSO Combined Sewage Overflow - a device that, when operating, pours combined rainwater & sewage into a waterway locations had reporting enabled for less than half the year.

Company Waterway Site Sewage Dumps Duration (Hours) Reporting %
Dwr Cymru Welsh Water Rhondda River Fawr REGENT ST CSO TREORCHY RHONDDA 154 2,155 99.9
Dwr Cymru Welsh Water Ogwr Fach DIMBATH AVE BLACKMILL BRIDGEND CSO 119 1,861 99.9
Dwr Cymru Welsh Water River Garw BETTWS ROAD CSO LLANGEINOR 124 1,850 96.8
Dwr Cymru Welsh Water Ogwr Fach Blackmill CSO & Storage Tanks Br'Nd 87 1,821 99.9
Dwr Cymru Welsh Water Ogwr Fawr CSO BELOW CEMETERY RD OGMORE VALE 139 1,820 73.7
Dwr Cymru Welsh Water River Ely ELY VALLEY ROAD CSO, 113 1,118 99.8
Dwr Cymru Welsh Water River Rhondda Brook Street Combined Sewer Overflow 149 1,099 99.9
Dwr Cymru Welsh Water River Garw STATION ROW CSO PONTYRHYL BRIDGEND 97 1,078 98.5
Dwr Cymru Welsh Water River Garw Fenton Place CSO Pont Y Cymer 121 994 99.9
Dwr Cymru Welsh Water Rhondda Fawr Station Rd CSO, Dinas, Porth 120 919 95.8
Dwr Cymru Welsh Water River Rhondda Fach Ferndale Road CSO Tylorstown RCT 86 903 99.4
Dwr Cymru Welsh Water Ogwr Fawr Nant Y Moel Junior School CSO 123 874 99.9
Dwr Cymru Welsh Water River Rhondda Fach R/O Tylorstown Primary School CSO, Tylorstown 115 868 98.1
Dwr Cymru Welsh Water River Rhondda Fach Rear of Fir St CSO, Ferndale 114 794 98.9
Dwr Cymru Welsh Water Rhondda Fawr Ton Pentre PS CSOTont Pentre RCT 128 779 99.6
Dwr Cymru Welsh Water Ogwr Fawr CSO BLANDY TERRACE ADJ ST JOHN ST 103 722 99.9
Dwr Cymru Welsh Water Nant Clydach A CSO at Clydach Vale Davies Street 122 709 98.9
Dwr Cymru Welsh Water Ogwr Fach CSO At Farmland Nr Elm Street 74 603 99.4
Dwr Cymru Welsh Water Nant-Y-Ci, The Ogwr Fawr TY YR AFON CSO TY YR AFON PANTARWEL 61 596 99.9
Dwr Cymru Welsh Water River Rhondda Fawr Rear of Richards Terrace CSO 50 562 89.9
Dwr Cymru Welsh Water River Rhondda Fach Ferndale Banana Tip CSO Additional 82 555 89.3
Dwr Cymru Welsh Water Rhondda Fawr River CSO GYLFACH ROAD PORTH RHONDDA 94 420 99.9
Dwr Cymru Welsh Water River Rhondda Fach CSO OPP 37 EDMONDES ST TYLORSTOWN 63 376 99.4
Dwr Cymru Welsh Water River Rhondda Fach CSO at CROSS STREET YNYSHIR R-C-T 99 348 99.9
Dwr Cymru Welsh Water River Rhondda Fach Rear of Blake St CSO, Maerdy 77 337 96.9
Dwr Cymru Welsh Water Rhondda Fawr River GLANNANT ST/DINAS ROAD CSO 85 318 99.2
Dwr Cymru Welsh Water River Rhondda Fawr CSO at Junct Ystrad/Church Road Ystrad 125 281 93.1
Dwr Cymru Welsh Water River Rhondda Fach Station Rd CSO, Ferndale 97 278 99
Dwr Cymru Welsh Water Rhondda Fawr River Blaencwm Rd/Tydraw Terrace CSO 74 268 99.1
Dwr Cymru Welsh Water Rhondda River CSO at Rear of George Street, Treherbert 73 267 97.7
Dwr Cymru Welsh Water River Rhondda Fach FERNDALE BANANA TIP CSO 75 260 98.7
Dwr Cymru Welsh Water River Rhondda Fach Aberrhondda Road CSO 62 247 98.3
Dwr Cymru Welsh Water Ogwr Fawr SWO East Bank Behind Gilead C Nant 88 217 93.6
Dwr Cymru Welsh Water Rhondda Fawr CSO O/S Welcome Inn, Tylacelyn Rd, Penygraig 82 215 99
Dwr Cymru Welsh Water River Rhondda Fach Ferndale Banana Tip No.1 CSO 22 212 23.1
Dwr Cymru Welsh Water River Rhondda Fach Highfield Industrial Estate CSO, Ferndale 63 209 97.8
Dwr Cymru Welsh Water Rhondda Fawr Gelligaled Pk CSO Ystrad Rhondda 62 184 99.1
Dwr Cymru Welsh Water Rhondda Fach CSO at Blaenllechau School St 58 173 71
Dwr Cymru Welsh Water Nant Clydach Railway Terrace CSO, Clydach Vale 60 166 97.1
Dwr Cymru Welsh Water River Rhondda A Combined Sewer Overflow, Trehafod 13 152 94.5
Dwr Cymru Welsh Water Rhondda Fach FERNDALE BANANA TIP SSO OLD SCHOOL 37 152 99.9
Dwr Cymru Welsh Water River Ely CSO at Mill Street, Tonyrefail 51 141 99.4
Dwr Cymru Welsh Water Rhondda R - Source To Conf River Rhondda Fach Penygraig Rd CSO, Penygraig 75 137 99
Dwr Cymru Welsh Water River Ogwr Fawr CSO Car Park New Ogmore Vale School 18 137 98.1
Dwr Cymru Welsh Water River Rhondda Fach Maerdy Station Road CSO 44 127 99.5
Dwr Cymru Welsh Water Rhondda Fach River PONTYGWAITH BRIDGE CSO ASSET 71188 55 123 97.7
Dwr Cymru Welsh Water Ogwr Fach Via A Surface Water Sewer Rear of Dan-Y-Bryn CSO, Gilfach Goch 61 117 93.4
Dwr Cymru Welsh Water Ogwr Fawr CSO at E E.Bank Opp SWO Northern 19 112 96.8
Dwr Cymru Welsh Water River Ely CSO at Tonyrefail, Waunrhydd Road 39 112 98.8
Dwr Cymru Welsh Water River Rhondda Llwynypia Rd CSO, Tonypandy 73 105 99.1
Dwr Cymru Welsh Water Rhondda Fach CSO at Blaenllechau Commercial & George St Jn 26 86 99.5
Dwr Cymru Welsh Water Rhondda River Fawr Llwynypia SPS 45 57 99.9
Dwr Cymru Welsh Water Rhondda Fawr REES STREET PUMPING STATION GELLI 39 44 99.9
Dwr Cymru Welsh Water River Rhondda CSO AT CADWGAN TERRACE TREHAFOD 16 41 99.9
Dwr Cymru Welsh Water Rhondda Fawr CSO to rear of 8 Griffin Park 13 40 62
Dwr Cymru Welsh Water River Rhondda Trehafod Pumping Station 51 39 99.9
Dwr Cymru Welsh Water Rhondda River Via A Culvert Rees Street 71 CSO, Pentre 81 37 96.1
Dwr Cymru Welsh Water River Rhondda Fach CSO at Wattstown-Bailey St Land Recla 15 35 71.1
Dwr Cymru Welsh Water River Rhondda Fach Blaenllechau Long Row CSO 14 33 80.5
Dwr Cymru Welsh Water River Rhondda Herbert St CSO 16 29 99.3
Dwr Cymru Welsh Water Rhondda Fawr CSO at Penycraig - Tylacelyn Road 42 27 99.2
Dwr Cymru Welsh Water Rhondda River Via A Culvert Old Brithweunydd Road CSO, Tonypandy 38 26 99.9
Dwr Cymru Welsh Water Ogwr Fawr CORBETT STREET CSO OGMORE VALE 10 23 99.9
Dwr Cymru Welsh Water Nant Clydach CSO at Tonypandy, Rear of De Winton St 11 17 99.9
Dwr Cymru Welsh Water Rhondda Fawr Treherbert Bute/Corbett/David St Junction CSO 5 15 99.8
Dwr Cymru Welsh Water Rhondda Fawr CSO OFF YNYSCYNON ROAD TREALAW 16 15 99.4
Dwr Cymru Welsh Water Rhondda Fach Cwmparc Railway Terrace CSO 15 13 99.7
Dwr Cymru Welsh Water Rhondda Fach Dolgwilym River Bridge CSO 13 11 99.8
Dwr Cymru Welsh Water River Garw CSO at Victoria Street 15 10 99.5
Dwr Cymru Welsh Water River Rhondda Fach James Terrace CSO 8 10 99.9
Dwr Cymru Welsh Water River Rhondda River Terrace CSO, Treorchy, Rhondda 23 10 99.9
Dwr Cymru Welsh Water River Ely CSO at Tynybryn Road Tonyrefail R-C-T 9 10 99.8
Dwr Cymru Welsh Water River Rhondda Fawr Treherbert Ind Est CSO Treherbert 7 8 99.9
Dwr Cymru Welsh Water Rhondda R - Source To Conf River Rhondda Fach Penygraig Nantgwyn St/Hill St Jn CSO 24 7 99.5
Dwr Cymru Welsh Water River Rhondda Fawr LEWIS STREET CSO & PUMPING STATION 8 5 99.9
Dwr Cymru Welsh Water River Ely CSO at Penrhiwfer Ashdale Rd CSO, rear of No23 6 4 99.8
Dwr Cymru Welsh Water Rhondda Fawr River Rear of William St CSO, Ystrad 7 3 99.8
Dwr Cymru Welsh Water Rhondda Fach CSO at FURNACE ROAD PONTYGWAITH RCT 9 2 97.7
Dwr Cymru Welsh Water Nant Y Ffosp Oakfield Terrace CSO, Nantymoel 8 2 100
Dwr Cymru Welsh Water River Cynon Pentre - Llewellyn Street CSO 6 2 99.6
Dwr Cymru Welsh Water River Rhondda Cymmer Rd CSO, Porth 4 1 100
Dwr Cymru Welsh Water Nant Muchydd Capel Farm PS Emergency Tonyrefai 1 1 99.9
Dwr Cymru Welsh Water Rhondda Fach River JUNCT OF BRONDEG AND PENRHYS ST CSO 2 1 99.7
Dwr Cymru Welsh Water River Ely Tonyrefail, Mill St CSO 4 1 100
Dwr Cymru Welsh Water Nant Ystradffernol Via A Culvert Blaen-y-Cwm Terrace CSO 3 1 90.7
Dwr Cymru Welsh Water Ogwr Fawr Via A Culverted Watercourse CSO at End of Railway Terrace, Ogmore Vale 4 1 97.3
Dwr Cymru Welsh Water Rhondda Fawr ELISABETH CLOSE CSO PENTRE RCT 2 1 99.9
Dwr Cymru Welsh Water Rhondda Fawr CSO at 136 Tyntyla Road, Tonypandy 3 0 99.8
Dwr Cymru Welsh Water Nant Cymparc Junction of Sunnyhill & Park Crescent CSO, Cwmparc 3 0 99.3
Dwr Cymru Welsh Water Rhondda Fawr River 2 Clarence St CSO, Pentre 1 0 98.7
Dwr Cymru Welsh Water Nant Abercerdin Via Surface Water Sewer CSO Nr Glannant, Heol Heulog 1 0 100
Dwr Cymru Welsh Water River Rhondda Fach CSO at Ferndale btw Taff St & Station Rd 1 0 100
Dwr Cymru Welsh Water River Ely Mill St CSO, Tonyrefail 1 0 57.8
Dwr Cymru Welsh Water Ogwr Fawr OGWR FAWR CSO OGMORE VALE 1 0 79.2
Dwr Cymru Welsh Water River Rhondda Fach Blaenllechau Taff St CSO 0 0 99.7
Dwr Cymru Welsh Water River Cynon CSO Meadow Street Pontycymmer 0 0 100
Dwr Cymru Welsh Water Rhondda Fach River East Rd CSO Tylorstown 0 0 99.8
Dwr Cymru Welsh Water River Rhondda Fawr GELLI CROSSING PUMPING STATION RHON 0 0 99.9
Dwr Cymru Welsh Water Rhonda Fawr River TREORCHY CSO - M/H AT SIDE OF BOYS 0 0 100
Dwr Cymru Welsh Water Rhondda River Treherbert - Opposite Railway CSO 0 0 100
Dwr Cymru Welsh Water Rhondda Fawr Treherbert Pumping Station, Park Close 0 0 99.9

Data Sources & Accuracy

EDM (Event Duration Monitoring) data and Consented Discharges to Controlled Waters with Conditions from Environment Agency & Data Map Wales, and Scottish Water

Experimental derived data from Thames Water API, Some data may be missing or inaccurate. Live sewage data from Stream Water API

Uses Environment Agency rainfall data from the real-time data API (Beta) - Rainfall data is delayed by up to two days.

This website is intended to provide an accurate representation of the Environment Agency data. The data is hard to use, and thus some errors may have been made. If you find something that is incorrect, please raise an issue at the GitHub issues page and we'll endeavour to fix it quickly.

This project is not associated, approved or endorsed by any of the companies whose logos you see here.

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Analysing sewage pollution by the Water Industry

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