Top of the Poops | Constituency Sewage Map | Dwyfor Meirionnydd

Marker shade

Select Another Constituency

Constituency

Select the constituency from the drop-down

✔ means we have live data (𝑥 if not)

Live data for Dwyfor Meirionnydd in 2026

So far this year (as of 25 Oct 2026, 17:45) there has been 40,800 hours of sewage overflows, from 195 CSO Combined Sewage Overflow - a device that, when operating, pours combined rainwater & sewage into a waterway s - that's 4.72 years!

Totals for Dwyfor Meirionnydd in 2025

176 Sites polluted by Dwr Cymru Welsh Water

10,941 sewage dumps

94,610 hours duration

Sewage pollution map of Dwyfor Meirionnydd: 10,941 spills in 2025, lasting 94,610 hours, by Dwr Cymru Welsh Water

That's 10.95 years. On average 30 times a day

Change Over Time

Take Action

Your local MP is Liz Saville-Roberts (Plaid Cymru) - Find out more about their interests, donors, and voting at They Work For You

Share this page, post a message, and tell others about the huge problem of sewage pollution across the UK

Company	Waterway	Site	Sewage Dumps	Duration (Hours)	Reporting %
Dwr Cymru Welsh Water	Nant Brisgyll	LLANFFESTINIOG STW	419	4,104	99.9
Dwr Cymru Welsh Water	Erch	ABERERCH WWTW	152	2,998	99.9
Dwr Cymru Welsh Water	Erch	FOURCROSSES Wastewater Treatment Works	238	2,713	99.9
Dwr Cymru Welsh Water	River Glaslyn	BEDDGELERT WASTE WATER TREATMENT	193	2,697	99.9
Dwr Cymru Welsh Water	Wen	CHWILOG STW	142	2,317	99.9
Dwr Cymru Welsh Water	River Goedol	BLAENAU FFESTINIOG WWTW	139	2,290	99
Dwr Cymru Welsh Water	Rhyd Hir	LLITHFAEN STW	115	2,219	99.6
Dwr Cymru Welsh Water	River Cadnant	BETHEL SEWAGE TRANSFER PS	129	1,968	99.6
Dwr Cymru Welsh Water	Mawddach Estuary	FAIRBOURNE WWTW	97	1,926	100
Dwr Cymru Welsh Water	River Rhythallt	LLANRUG WWTW FINAL	115	1,855	97.9
Dwr Cymru Welsh Water	Dwyfawr	LLANYSTUMDWY A WWTW	124	1,852	99.8
Dwr Cymru Welsh Water	Tremadog Bay	CRICCIETH STW FINAL	124	1,829	99.8
Dwr Cymru Welsh Water	Mawddach	Llanelltyd PS CSO	99	1,818	99.5
Dwr Cymru Welsh Water	Caernarfon Bay	NEFYN PUMPING STATION	131	1,816	99.9
Dwr Cymru Welsh Water	River Cedron	PENTREFELIN STW	104	1,634	99.9
Dwr Cymru Welsh Water	Tyddin Drain To Coastal Waters	TREFOR CAERNARFON	125	1,620	99.5
Dwr Cymru Welsh Water	River Llyfni	Nantlle PS	102	1,553	99.9
Dwr Cymru Welsh Water	River Llyfni	LLANLLYFNI CAERNARFON STW	113	1,504	99.8
Dwr Cymru Welsh Water	Dwyfawr	GARNDOLBENMAEN STW	98	1,393	99.9
Dwr Cymru Welsh Water	River Seiont	Pont Rhythallt Pumping Station	140	1,380	99.9
Dwr Cymru Welsh Water	River Gwyrfai	WAUNFAWR STW (FINAL EFFLUENT)	92	1,292	99.9
Dwr Cymru Welsh Water	River Seiont	CAERNARFON STW	90	1,251	99.8
Dwr Cymru Welsh Water	Mawddach	DOLGELLAU STW	77	1,232	99.9
Dwr Cymru Welsh Water	River Seiont	PENISARWAUN WWTW FE	161	1,199	99.9
Dwr Cymru Welsh Water	River Seiont	LLANBERIS WwTW	137	1,196	99.8
Dwr Cymru Welsh Water	River Mawddach	Penmaenpool PS	111	1,190	98.8
Dwr Cymru Welsh Water	Of River Rhyd Hir	EFAILNEWYDD STW	281	1,144	92.8
Dwr Cymru Welsh Water	River Dyfi	ABERDYFI WHARF PS SEAVIEW TERRACE	59	1,092	99.9
Dwr Cymru Welsh Water	River Geirch	NEFYN WWTW	99	1,060	100
Dwr Cymru Welsh Water	River Geirch	NEFYN WWTW	104	1,018	99.9
Dwr Cymru Welsh Water	Gwyrfai	LLANFAGLAN WWTW FINAL EFFLUENT	91	1,002	99.9
Dwr Cymru Welsh Water	Tremadog Bay	HARLECH TERMINAL PS (OUTFALL A)	57	991	99.9
Dwr Cymru Welsh Water	River Prysor	CSO at Trawsfynydd WwTW	70	973	99.8
Dwr Cymru Welsh Water	River Dwyryd	Penrhyndeudraeth CSO	127	928	99.9
Dwr Cymru Welsh Water	River Bowydd	CWM BOWYDD SSO BLAENAU FFESTINIOG	109	916	99.9
Dwr Cymru Welsh Water	Unnamed Stream	HARLECH TERMINAL PS (OUTFALL B)	55	914	99.9
Dwr Cymru Welsh Water	River Rhyd Hir	LLANNOR STW (SETTLED STORM)	112	899	99.9
Dwr Cymru Welsh Water	Of River Soch	MYNYTHO STW - STORM OVERFLOW	118	885	99.9
Dwr Cymru Welsh Water	River Dee	CORWEN WWTW FINAL EFFLUENT	58	881	99.9
Dwr Cymru Welsh Water	Estuarial Waters Of River Dwyryd	MAENTWROG WWTW	68	854	99.9
Dwr Cymru Welsh Water	Ardudwy Marsh Main Drain	DYFFRYN ARDUDWY WWTW FINAL EFFLUENT	56	850	99.9
Dwr Cymru Welsh Water	River Llyfni	Talysarn No 3 - CSO	86	827	99.9
Dwr Cymru Welsh Water	Dulas North	LOWER CORRIS STW	72	800	81.4
Dwr Cymru Welsh Water	Cwmllechen	BONTDDU STW	82	789	99.9
Dwr Cymru Welsh Water	River Geirch	Edern SPS CSO	69	785	99.8
Dwr Cymru Welsh Water	River Ceunant Sych	CSO at Land Off A496 Manod Blaenau Ffesti	123	773	97.4
Dwr Cymru Welsh Water	River Dwyfawr	LLANYSTUMDWY PUMPING STATION	64	728	99.7
Dwr Cymru Welsh Water	Cardigan Bay	BARMOUTH WWTW LONG SEA OUTFALL	173	707	99.8
Dwr Cymru Welsh Water	River Dee	BALA WWTW	92	693	99.8
Dwr Cymru Welsh Water	Unknown	CSO at Tai Craig-y-don Cwymyglo	41	653	97.7
Dwr Cymru Welsh Water	River Eden	BRONABER STW	78	636	99.7
Dwr Cymru Welsh Water	River Barlwyd	LAND OPP GLANLLYN NR OAKLEY SQUARE CSO	117	634	99.5
Dwr Cymru Welsh Water	River Caledffrwd	Llwyn Celyn CSO Deinolen	129	629	97.9
Dwr Cymru Welsh Water	Tafarn Helyg	GELLILYDAN STW	81	607	99.9
Dwr Cymru Welsh Water	Nant Brisgyll	CSO at Llan Ffestiniog Sewage Treatment Works	50	568	100
Dwr Cymru Welsh Water	River Llyfni	Talysarn No 4 - CSO	87	567	99.8
Dwr Cymru Welsh Water	Tremadog Bay	Llanbedrog SPS	36	561	99.7
Dwr Cymru Welsh Water	River Prysor	TRAWSFYNYDD STW	50	555	100
Dwr Cymru Welsh Water	Coastal Waters	FAIRBOURNE WWTW STORM TANKS	28	554	99.7
Dwr Cymru Welsh Water	River Gwyrfai	Bontnewydd CSO	98	515	94.7
Dwr Cymru Welsh Water	Cyt Mawr Stream	TALSARNAU STW	73	508	99.9
Dwr Cymru Welsh Water	River Rhydhir	LON COB BACH PS PWLLHELI	67	494	98.8
Dwr Cymru Welsh Water	Tyddyn Drain To Coastal Waters	TREFOR WWTW	38	482	100
Dwr Cymru Welsh Water	River Dyfrdwy	The Eagles CSO, Llanwchllyn	60	479	98.9
Dwr Cymru Welsh Water	Llyfni	PONTLLYFNI PS	44	465	99.9
Dwr Cymru Welsh Water	River Goedol	CSO at Land Off Pencefn Road Tanygrisiau	80	446	98.9
Dwr Cymru Welsh Water	River Glaslyn	CSO at Porthmadog Borth-Y-Gest SPS	135	446	99.8
Dwr Cymru Welsh Water	River Glaslyn	CSO at Beddgelert East Bank Afon Glaslyn	59	438	97.5
Dwr Cymru Welsh Water	River Carrog	CSO at Caernarfon Hen Gastell No5	80	437	99.1
Dwr Cymru Welsh Water	Coastal Waters Of Cardigan Bay	TYWYN STW MORFA GWYLLT TYWYN	83	432	99.8
Dwr Cymru Welsh Water	Coastal Waters	CRICCIETH EAST PS , ,	56	399	96.4
Dwr Cymru Welsh Water	Tremadog Bay	CRICCIETH WEST PS , ,	51	398	99
Dwr Cymru Welsh Water	Dysynni Low Level Drainage Cha	TYWYN STW MORFA GWYLLT TYWYN ,	73	385	99.8
Dwr Cymru Welsh Water	Unnamed Ditch	CASTELL PUMPING STATION	39	375	99.4
Dwr Cymru Welsh Water	Tremadog Bay	CRICCIETH EAST PS	32	365	99.8
Dwr Cymru Welsh Water	Seiont	CAERNARFON PONT SEIONT PS	41	354	99.7
Dwr Cymru Welsh Water	River Gwyrfai	CSO at Bontnewydd Glanrafon No10	73	351	99.1
Dwr Cymru Welsh Water	River Wnion	Marian Mawr CSO	105	343	99.9
Dwr Cymru Welsh Water	River Llyfni	Llanllyfni Glan Aber CSO	130	340	99
Dwr Cymru Welsh Water	Unnamed Ditch	ARTHOG TERRACE SEWAGE PUMPING ST	41	334	99.9
Dwr Cymru Welsh Water	River Goedol	BLAENAU FFESTINIOG WWTW (Settled STORM)	22	334	100
Dwr Cymru Welsh Water	Unnamed Stream	Clynnog Fawr CSO at PS	68	333	99.9
Dwr Cymru Welsh Water	Unnamed Stream	CSO At Corwen Rear Of The Pavillion	73	329	97.9
Dwr Cymru Welsh Water	Tremadog Bay	LLANDANWG TERMINAL PS	25	315	99.9
Dwr Cymru Welsh Water	Dyffryn Main Drain	DYFFRYN ARDUDWY WWTW STORM	23	310	100
Dwr Cymru Welsh Water	River Seiont	CAERNARFON WWTW INLET PUMP ST 6MM	83	301	99.8
Dwr Cymru Welsh Water	Cyt Bach Surface Watercourse	SNOWDON STREET PS	88	300	99.9
Dwr Cymru Welsh Water	River Ceidiog	LLANDRILLO STW	20	299	100
Dwr Cymru Welsh Water	River Blaen-Y-Cae	BRYNCIR STW	59	297	99.9
Dwr Cymru Welsh Water	River Caledffwrd	BRYNREFAIL MAIN SPS	52	296	99.9
Dwr Cymru Welsh Water	Dee	CYNWYD STW FINAL EFFLUENT	83	292	99.9
Dwr Cymru Welsh Water	River Llyfni	Settled Storm Sewage at Llanllyfni WwTW	27	280	99.9
Dwr Cymru Welsh Water	Llyn Nantlle Uchaf	Nantlle No 5-CSO	68	272	98.7
Dwr Cymru Welsh Water	Cegin	RHIWLAS STW	99	266	99.9
Dwr Cymru Welsh Water	Goch Bach	CSO Near Castle Gift Shop Llanberis	50	266	99.6
Dwr Cymru Welsh Water	Carrog	CAERNARFON - RHOSTRYFAN CSO NO	81	262	99.9
Dwr Cymru Welsh Water	Un-Named Stream Into Llifon	Dorlan Goch CSO	77	260	98.8
Dwr Cymru Welsh Water	River Artro	LLANBEDR TERMINAL PS (STORM)	36	250	99.7
Dwr Cymru Welsh Water	River Ceidiog	Llandrillo STW PS CSO	64	238	99.9
Dwr Cymru Welsh Water	Rhyd	CAERNARFON - GLANRHYD SSO NO.	63	220	96
Dwr Cymru Welsh Water	River Geirch	MORFA NEFYN PUMPING STATION CSO (B)	80	207	98.7
Dwr Cymru Welsh Water	Coastal Waters	Llwyngwril SPS	32	202	99.9
Dwr Cymru Welsh Water	River Wnion	STAYLITTLE LANE CSO	51	198	99.9
Dwr Cymru Welsh Water	Gwyrfai	CAERNARFON - RHOSTRYFAN CSO NO	56	197	99.5
Dwr Cymru Welsh Water	Cadnant - Caernarfon	SSO AT MILL LANE CAERNARFON	87	194	99.9
Dwr Cymru Welsh Water	Tremadog Bay	MORFA BYCHAN WWTW	58	184	99.9
Dwr Cymru Welsh Water	River Dysynni	Abergynolwyn STW (Settled Storm)	38	181	99.9
Dwr Cymru Welsh Water	Desach	ABERDESACH PS	72	171	99.9
Dwr Cymru Welsh Water	Glaslyn Estuary	PORTHMADOG STW STORM STORAGE PORT	56	164	99.9
Dwr Cymru Welsh Water	River Llifon	Caernarfon - Llwyn Gwalch CSO Groes	59	149	99.9
Dwr Cymru Welsh Water	Menai Strait	FELINHELI PS (QUAY COTTAGE) , ,	23	148	99.9
Dwr Cymru Welsh Water	Tremadog Bay	CRICCIETH WEST PS	30	147	93.7
Dwr Cymru Welsh Water	River Llyfni	PONTLLYFNI STW	28	142	99.9
Dwr Cymru Welsh Water	River Henddol	FAIRBOURNE PUMPING STATION	22	139	99.9
Dwr Cymru Welsh Water	Un-Named Watercourse	BRYNCOCH SEWAGE PUMPING STATION	13	131	99.9
Dwr Cymru Welsh Water	River Glaslyn	BORTH Y GES PS	41	125	99.7
Dwr Cymru Welsh Water	River Gwyrfai	Bontnewydd CSO Ysgol Gynradd Bontne	47	124	99.9
Dwr Cymru Welsh Water	Ffos Ddu	Marian Mawr Splitter Chamber CSO	22	111	99.8
Dwr Cymru Welsh Water	River Hwch	Llanberis CSO NO. 2	45	104	97.8
Dwr Cymru Welsh Water	River Seiont	Peblig Industrial Estate CSO	37	97	98.2
Dwr Cymru Welsh Water	Menai Straits	CROSSVILLE CSO	67	95	99.9
Dwr Cymru Welsh Water	Nant Brisgyll	CSO at Llanffestiniog STW	15	95	100
Dwr Cymru Welsh Water	Coastal Waters - River Daron	ABERDARON PS	25	86	99.8
Dwr Cymru Welsh Water	Groundwater Via Infiltration System	WESLEYAN TERRACE SEWAGE PUMPING ST	8	86	99.9
Dwr Cymru Welsh Water	River Dysynni	Abergynolwyn SPS	36	83	99.9
Dwr Cymru Welsh Water	River Prysor	Trawsfynydd Maesgwindy Est CSO	55	82	99.9
Dwr Cymru Welsh Water	River Glaslyn	BRITANNIA PS	10	80	99.9
Dwr Cymru Welsh Water	Ditch	Idris Villas Sewage Pumping Station	40	76	99.9
Dwr Cymru Welsh Water	River Llan	CAERNARFON - PENYGROES SSO NO.	53	75	99.9
Dwr Cymru Welsh Water	River Penrhos	PENRHOS CAMP STW - SCREENED ST	31	74	99.8
Dwr Cymru Welsh Water	River Cadnant	BETHEL CSO BETHEL NEAR CAERNARFON	31	67	99.2
Dwr Cymru Welsh Water	River Rhyd Hir Estuary	Y MAES CSO	32	61	99.8
Dwr Cymru Welsh Water	Stream Leading To Cyt Stre	TREMADOG SSO	16	54	99.9
Dwr Cymru Welsh Water	Cadnant	BETHEL SSO NO. 3	15	51	99.9
Dwr Cymru Welsh Water	Llyn Padarn	LLANBERIS PS , ,	15	47	98.9
Dwr Cymru Welsh Water	River Wen	AFONWEN WASTEWATER TREATMENT WORKS	10	40	99.9
Dwr Cymru Welsh Water	Unnamed Ditch	GLASFRYN TERRACE STW ARTHOG	5	36	99.9
Dwr Cymru Welsh Water	Unnamed Watercourse	CAERNARFON MARGARET STREET SSO	57	36	98.7
Dwr Cymru Welsh Water	Artro	LLANBEDR WWTW	12	35	99.8
Dwr Cymru Welsh Water	Cardigan Bay	BARMOUTH WWTW OUTFALL TO MLWS	23	32	99.9
Dwr Cymru Welsh Water	Dwyryd	PENRHYNDEUDRAETH OUTFALL-SCREE	5	30	99.8
Dwr Cymru Welsh Water	River Seiont	Caernarfon WWTW Inlet Pump ST 6mm SPS	18	28	99.8
Dwr Cymru Welsh Water	Un-Named Stream	PORTHMADOG - LOMBARD STREET SS	52	20	99.9
Dwr Cymru Welsh Water	Unnamed Stream	FRIOG SEWAGE PUMPING STATION	9	18	99.9
Dwr Cymru Welsh Water	Unnamed Stream	Trefor CSO	17	17	41.7
Dwr Cymru Welsh Water	River Y Llan	LLANFACHRETH WWTW	26	16	95.4
Dwr Cymru Welsh Water	River Daron	ABERDARON WASTEWATER TREATMENT WKS	15	15	99.4
Dwr Cymru Welsh Water	Tremadog Bay	CSO at Llandanwg SPS	2	14	99.8
Dwr Cymru Welsh Water	River Prysor	CSO at Trawsfynydd Near Bron Gwyndy	23	14	97.5
Dwr Cymru Welsh Water	Cadnant	MIN-Y-NANT CSO	27	14	99.7
Dwr Cymru Welsh Water	Barlwyd	BLAENAU FFESTINIOG NO2	12	13	98.6
Dwr Cymru Welsh Water	Unnamed Stream	HARLECH OUTSIDE LAUNDRY	17	12	99.9
Dwr Cymru Welsh Water	Un-Named Watercourse	LLANERCH CSO	25	9	99.6
Dwr Cymru Welsh Water	Tremadog Bay	MORFA BYCHAN WWTW	2	9	100
Dwr Cymru Welsh Water	Angell	Aberangell No1 PS	1	8	97.4
Dwr Cymru Welsh Water	River Dee	Corwen Corner Station Yard CSO	4	7	99.6
Dwr Cymru Welsh Water	Tremadog Bay	CSO ON SEWER (CRICCIETH BEACH)	6	7	99.9
Dwr Cymru Welsh Water	Unnamed Stream	CSO Rear Of Prysor Filling Station Traw	17	7	99.9
Dwr Cymru Welsh Water	River Penrhos	CSO at Penrhos WwTW	6	7	100
Dwr Cymru Welsh Water	River Mawddach	Llanelltyd CSO	13	7	97.3
Dwr Cymru Welsh Water	Mawddach Estuary	BARMOUTH HARBOUR PUMPING STATION	16	7	99.9
Dwr Cymru Welsh Water	River Soch Estuary	ABERSOCH HARBOUR PUMPING STATION	4	6	99.9
Dwr Cymru Welsh Water	Glaslyn Estuary Within Glaslyn	PORTHMADOG STW STORM STORAGE PORT	7	6	99.9
Dwr Cymru Welsh Water	River Caledffrwd	CSO at Pen yr Olchfa Clwt Y Bont Deiniolen	4	3	98.1
Dwr Cymru Welsh Water	Esturial Waters River Erch	GLAN Y DON PS PWLLHELI	6	3	99.3
Dwr Cymru Welsh Water	Dulas North	Minffordd St CSO, Corris	5	3	96.6
Dwr Cymru Welsh Water	River Dwyryd	Harlech Rum Hole CSO	12	3	99
Dwr Cymru Welsh Water	Nant Y Cyt	CHAPEL STREET/MADOG STREET PORTHM	9	3	99.5
Dwr Cymru Welsh Water	River Dwyryd	MAENTWROG CSO	5	1	100
Dwr Cymru Welsh Water	River Cyll-Y-Felin	CSO at Aberdaron WwTW	2	1	99.5
Dwr Cymru Welsh Water	River Glaslyn	AMMANDA TERRACE BORTH Y GEST PORTHM	3	0	100
Dwr Cymru Welsh Water	Cadnant	BETHEL SSO NO. 2	3	0	99.9
Dwr Cymru Welsh Water	River Fathew	BRYNCRUG PS	2	0	99.6
Dwr Cymru Welsh Water	River Bowydd	Blaenau Ffestiniog CSO No 3	2	0	99.9
Dwr Cymru Welsh Water	Mawddach	MAWDDACH CRESCENT PUMPING STATION	2	0	99.8
Dwr Cymru Welsh Water	Menai Straits	BALACLAVA ROAD SEWAGE PUMPING ST	1	0	99.8
Dwr Cymru Welsh Water	River Siont	ANGLESEY ARMS PUMPING STATION	0	0	100
Dwr Cymru Welsh Water	Nant Y Cyt	BAKERS LANE/CHANDLERS PLACE PORTH	0	0	99.7
Dwr Cymru Welsh Water	River Erch	BRIDGE GARAGE PWLLHELI	0	0	99.6
Dwr Cymru Welsh Water	River Bowydd	Blaenau Ffestiniog WWTW Settled Storm (B)	0	0	100
Dwr Cymru Welsh Water	Menai Straits	CAERNARFON BANK QUAY PS	0	0	99.9
Dwr Cymru Welsh Water	Dee Via Surface Water Sewer And Culvert	Corwen Clawdd Poncen PS	0	0	99.9
Dwr Cymru Welsh Water	River Mawddach	Dolgellau Main PS	0	0	99.9
Dwr Cymru Welsh Water	Menai Strait	FELINHELI PS (ADJ TO QUAY TOILETS)	0	0	99.9
Dwr Cymru Welsh Water	Menai Strait	FELINHELI PS (OPP SEA CADET CORPS)	0	0	99.9
Dwr Cymru Welsh Water	Esturial Waters Of River Erch	GIMBLET ROCK TIDAL TANK CSO	0	0	99.9
Dwr Cymru Welsh Water	Unnamed Culvert To River Artro	Llanbedr CSO	0	0	100
Dwr Cymru Welsh Water	Un-Named Stream	MORFA BYCHAN WWTW	0	0	100
Dwr Cymru Welsh Water	Esturial Waters Of River Erch	MORFA GARREG PS PWLLHELI	0	0	99.9
Dwr Cymru Welsh Water	Groundwater Via Infiltration System	ST MARY'S SEWAGE PUMPING STATION	0	0	99.1
Dwr Cymru Welsh Water	Menai Strait	WATERLOO PORT SEWAGE PUMPING ST	0	0	99.2

Dwyfor Meirionnydd

Select Another Constituency

Live data for Dwyfor Meirionnydd in 2026

Totals for Dwyfor Meirionnydd in 2025

176 Sites polluted by Dwr Cymru Welsh Water

Change Over Time

Take Action

Constituencies near Dwyfor Meirionnydd

Waterways in Dwyfor Meirionnydd

We need your support!

Pollution Summary 2025

Data Sources & Accuracy

Media Queries

Please Support Us