Top of the Poops | Constituency Sewage Map - 2025 Data| Merthyr Tydfil and Aberdare

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View Annual Sewage Data

You're looking at the totals that we have calculated for sewage in Merthyr Tydfil and Aberdare for 2025. It is an estimate, based on very poor quality live data from the Water Companies. This may not align with the 'official' reported sewage values from the water companies, which is reported in April following then end of the year - so 2025 numbers are reported in April 2026.

What's a potential overflow? If the CSO goes 'Offline' while its Overflowing, we don't know if it stopped overflowing until we get a 'Stop' event.

Totals for Merthyr Tydfil and Aberdare in 2025

Sewage15,307 hours

Monitoring offline0 hours

Potential pollution0 hours

Storm overflows80

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Constituencies near Merthyr Tydfil and Aberdare

Company	Site Name	Receiving Waterway	Overflow Days	Total Duration (hours)	Offline/Potential Pollution
Dwr Cymru Welsh Water	Hirwaun Industrial Estate WwTW Storm Overflow	Afon Camnant	133	2,853h 42m	-
Dwr Cymru Welsh Water	Mikes Field Storm Overflow	River Cynon	104	1,409h 50m	-
Dwr Cymru Welsh Water	Pontsticill WwTW Storm Overflow	River Taff	72	1,170h 30m	-
Dwr Cymru Welsh Water	Aberaman Park West Storm Overflow	River Cynon	101	1,124h 25m	-
Dwr Cymru Welsh Water	East of Rounabout A4102 jct with High Street Storm Overflow	Morlais Brook	98	655h 20m	-
Dwr Cymru Welsh Water	Cilmery WwTW Storm Overflow	Afon Chwefri	64	586h 33m	-
Dwr Cymru Welsh Water	Pontbren Storm Overflow	River Cynon	69	584h 9m	-
Dwr Cymru Welsh Water	Pontrhun Bridge Storm Overflow	River Taff	80	515h 38m	-
Dwr Cymru Welsh Water	Oakland Street Bedlinog Storm Overflow	River Taff	58	496h 42m	-
Dwr Cymru Welsh Water	Meirion Street Roundabout Trecynon Storm Overflow	River Cynon	80	470h 38m	-
Dwr Cymru Welsh Water	Pant-Y-Cerdin Storm Overflow	Aberdare Canal	82	423h 56m	-
Dwr Cymru Welsh Water	Merthyr Road Bridge Storm Overflow	River Cynon	68	389h 32m	-
Dwr Cymru Welsh Water	Monk Street No1 Storm Overflow	River Cynon	75	383h 27m	-
Dwr Cymru Welsh Water	Gellifaelog Old Road Storm Overflow	Morlais Brook	47	343h 40m	-
Dwr Cymru Welsh Water	Maes Y Ffion Storm Overflow	Nant-Y-Derlwyn	57	332h 8m	-
Dwr Cymru Welsh Water	Trelewis Glynbargoed Road Storm Overflow	Pandy Brook	77	279h 46m	-
Dwr Cymru Welsh Water	Merthyr Tydfil Industrial Park Storm Overflow	Pentrebach Brook	56	261h 7m	-
Dwr Cymru Welsh Water	Dare Road Storm Overflow	River Dare	37	246h 52m	-
Dwr Cymru Welsh Water	Station Street Aberdare Storm Overflow	River Cynon	65	238h 12m	-
Dwr Cymru Welsh Water	Merthyr Tydfil College Car Park Storm Overflow	River Taff	50	217h 28m	-
Dwr Cymru Welsh Water	Bethesda Street Merthyr Tydfil Storm Overflow	River Taff	64	200h 36m	-
Dwr Cymru Welsh Water	Bro Deg 2 Storm Overflow	River Cynon	50	191h 26m	-
Dwr Cymru Welsh Water	Gladstone Street Storm Overflow	Tributary of Afon Aman	21	151h 7m	-
Dwr Cymru Welsh Water	Tan Y Bryn Gardens Llwydcoed Overflow	River Cynon	40	134h 11m	-
Dwr Cymru Welsh Water	Trenant 1 Storm Overflow	River Cynon	52	124h 16m	-
Dwr Cymru Welsh Water	Fiddlers Elbow Quakers Yard Storm Overflow	River Taff	21	124h 4m	-
Dwr Cymru Welsh Water	Tram Road Side Storm Overflow	River Taff	19	118h 24m	-
Dwr Cymru Welsh Water	Rocky Road 1 Storm Overflow	Nant Morlais	49	97h 4m	-
Dwr Cymru Welsh Water	Tai Mawr Way Storm Overflow	River Taff	34	96h 50m	-
Dwr Cymru Welsh Water	Heol Pendarren Storm Overflow	Ditch to Nant Gwrangon	36	92h 1m	-
Dwr Cymru Welsh Water	Pen-Y-Darren Rd jct with Gwalia Place Storm Overflow	Morlais Brook	51	89h 37m	-
Dwr Cymru Welsh Water	Bute Place Hirwaun Storm Overflow	River Cynon	24	89h 6m	-
Dwr Cymru Welsh Water	Bro Deg 1 Storm Overflow	River Cynon	38	86h 48m	-
Dwr Cymru Welsh Water	Dean Street Aberdare Storm Overflow	River Cynon	39	62h 45m	-
Dwr Cymru Welsh Water	Aberaman Curre Street Storm Overflow	Unnamed Stream	21	50h 51m	-
Dwr Cymru Welsh Water	Wind Street Storm Overflow	River Amman	32	47h 25m	-
Dwr Cymru Welsh Water	Llwydcoed Road New Scales Houses Storm Overflow	Unnamed Tribuatary of Afon Cynon	15	46h 18m	-
Dwr Cymru Welsh Water	Glan Road Storm Overflow	River Dare	18	45h 38m	-
Dwr Cymru Welsh Water	Cyfarthfa Road Storm Overflow	River Taff	27	44h 8m	-
Dwr Cymru Welsh Water	Elizabeth Street Storm Overflow	Tributary of River Cynon	13	41h 17m	-
Dwr Cymru Welsh Water	Sion Terrace Storm Overflow	River Cynon	18	38h 10m	-
Dwr Cymru Welsh Water	Commercial Street Aberdare Overflow	River Cynon	39	35h 5m	-
Dwr Cymru Welsh Water	Merthyr Vale Trunk Sewer Storm Overflow	River Taff	4	30h 16m	-
Dwr Cymru Welsh Water	Swan Street Merthyr Tydfil Storm Overflow	River Taff	17	26h 42m	-
Dwr Cymru Welsh Water	David Street Aberaman Storm Overflow	River Cynon	2	24h 47m	-
Dwr Cymru Welsh Water	Pont-y-Cefn Storm Overflow	Taf Fechan	15	23h 53m	-
Dwr Cymru Welsh Water	Yew Street Storm Overflow	River Taff	10	21h 26m	-
Dwr Cymru Welsh Water	Cardiff Road Aberaman Storm Overflow	River Cynon	12	19h 19m	-
Dwr Cymru Welsh Water	Canal Road Cwmbach Storm Overflow	River Cynon	8	18h 18m	-
Dwr Cymru Welsh Water	Goitre Lane Storm Overflow	Goitre Brook	13	17h 54m	-
Dwr Cymru Welsh Water	Nr Aberaman Park Ind. Est. Storm Overflow	RiverAman	11	14h 30m	-
Dwr Cymru Welsh Water	Bron Haul Storm Overflow	River Cynon	5	14h 13m	-
Dwr Cymru Welsh Water	Bro Deg Canal Road Junction Storm Overflow	River Cynon	27	13h 48m	-
Dwr Cymru Welsh Water	Erw Las Rear Footpath Storm Overflow	River Cynon	9	12h 8m	-
Dwr Cymru Welsh Water	Troedyrhiw Storm Overflow	River Taff	2	10h 29m	-
Dwr Cymru Welsh Water	Foundry View Aberaman No 2 Storm Overflow	River Amman	9	10h 20m	-
Dwr Cymru Welsh Water	Pit Place Cwmbach Overflow	River Cynon	7	9h 12m	-
Dwr Cymru Welsh Water	Cwmbach Storm Overflow	River Cynon	2	9h	-
Dwr Cymru Welsh Water	Abernant Road Aberdare Storm Overflow	Nant Wenallt	16	8h 11m	-
Dwr Cymru Welsh Water	Glancynon Terrace Storm Overflow	Nant Gwawr	13	7h 38m	-
Dwr Cymru Welsh Water	Phyllis Street Storm Overflow	River Taff	10	6h 55m	-
Dwr Cymru Welsh Water	Hirwaun Mangoed Storm Overflow	River Cynon	4	3h 43m	-
Dwr Cymru Welsh Water	Tudor Terrace Rear Storm Overflow	Gadlys Feeder	4	3h 27m	-
Dwr Cymru Welsh Water	Park View Terrace Storm Overflow	River Cynon	5	3h 23m	-
Dwr Cymru Welsh Water	Fforchaman Road Cwmaman	River Amman	1	2h 45m	-
Dwr Cymru Welsh Water	Wellington St No1 Storm overflow	River Cynon	3	1h 28m	-
Dwr Cymru Welsh Water	Bryngolwg Storm Overflow	River Cynon	1	0h 59m	-
Dwr Cymru Welsh Water	Cynon Street Storm Overflow	Unnamed Tributary to Afon Amman	1	0h 29m	-
Dwr Cymru Welsh Water	Rocky Road 2 Storm Overflow	Morlais Brook	1	0h 16m	-
Dwr Cymru Welsh Water	Cwmbach Maeshyfryd Stoem Overflow	River Cynon	1	0h 15m	-
Dwr Cymru Welsh Water	Foundry View Aberaman No 1 Overflow	River Amman	1	0h 15m	-
Dwr Cymru Welsh Water	Market Street Dowlais Storm Overflow	Unnamed Tributary Leading to Nant Morlais	1	0h 15m	-
Dwr Cymru Welsh Water	Hirwaun Tramway Storm Overflow	Unnamed Stream	0	0h	-
Dwr Cymru Welsh Water	Well Place Storm Overflow	River Cynon	0	0h	-
Dwr Cymru Welsh Water	Muriel Terrace Merthyr Tydfil Overflow	River Taff	0	0h	-
Dwr Cymru Welsh Water	Trecynon Harriet Street Storm Overflow	Nant-Y-Derlwyn	0	0h	-
Dwr Cymru Welsh Water	Rodericks Terrace Storm Overflow	River Taff	0	0h	-
Dwr Cymru Welsh Water	Aberfan Trunk Sewer Storm Overflow	River Taff	0	0h	-
Dwr Cymru Welsh Water	Balaclava Road 2 Storm Overflow	Morlais Brook	0	0h	-
Dwr Cymru Welsh Water	Wyndham Crescent Aberaman Storm Overflow	River Cynon	0	0h	-

Company

Site Name

Receiving Waterway

Overflow Days

Total Duration (hours)

Offline/Potential Pollution

Dwr Cymru Welsh Water

Hirwaun Industrial Estate WwTW Storm Overflow

Afon Camnant

133

2,853h 42m

Dwr Cymru Welsh Water