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Ynys Môn - Live Sewage

Polluted by sewage 10,466 hours in 2026 - That's 1.21 years so far..

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

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View Annual Sewage Data

You're looking at the totals that we have calculated for sewage in Ynys Môn so far for 2026. It is an estimate, based on very poor quality live data from the Water Companies. The water companies report their sewage to the Environment Agency every year in April. You can see the last reported year in the other page

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.

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Constituencies near Ynys Môn

Daily Data

Jan - 3,320 hours
Feb - 4,049 hours
Mar - 1,929 hours
Apr - 912 hours
May - 254 hours
Jun - 0 hours
Jul - 0 hours
Daily data is experimental and data is not guaranteed to be accurate. Please inform us of any issue, we will fix.
Please note: We don't have rainfall data for Wales. If you know where to source it please let us know!
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Totals so far

Company Site Name Receiving Waterway Overflow Days Total Duration (hours) Offline/Potential Pollution
Dwr Cymru Welsh Water Llanfachraeth WwTW Overflow River Alaw 137 2,834h 24m -
Dwr Cymru Welsh Water Bryngwran WwTW Overflow Crigyll 110 1,826h 27m -
Dwr Cymru Welsh Water Llangaffo WwTW Storm Overflow Unnamed Stream 126 1,022h 17m -
Dwr Cymru Welsh Water Talwrn Llangefni Storm Overflow Unnamed Ditch 35 562h 45m -
Dwr Cymru Welsh Water Green Terrace Llangaffo Storm Overflow Unnamed Ditch 34 561h 12m -
Dwr Cymru Welsh Water Brynsiencyn WwTW Storm Overflow Menai Strait 76 514h 14m -
Dwr Cymru Welsh Water Llandegfan Menai Bridge Storm Overflow Afon Cadnant 29 405h 26m -
Dwr Cymru Welsh Water Craig Y Don Storm Overflow Afon Goch 37 387h -
Dwr Cymru Welsh Water Menai Llandegfan Storm Overflow Menai Strait 19 295h 49m -
Dwr Cymru Welsh Water Llanfechell WwTW Storm Overflow Afon Meddanen 17 263h 9m -
Dwr Cymru Welsh Water Train Station Gaerwen Storm Overflow Tributary of Afon Braint 16 180h 15m -
Dwr Cymru Welsh Water Bull Bay Storm Overflow Bull Bay 21 155h 30m -
Dwr Cymru Welsh Water Hermon Malltraeth Storm Overflow Afon Frechwen 9 139h 30m -
Dwr Cymru Welsh Water Llaneilian Storm Overflow Coastal Waters 8 129h 45m -
Dwr Cymru Welsh Water Lon Sardis Bodffordd Storm Overflow Cefni Reservoir Bypass Channel 24 114h -
Dwr Cymru Welsh Water Aberffraw WwTW Storm Overflow Aberffraw Bay 9 99h 20m -
Dwr Cymru Welsh Water Llanfair Pwllgwyngyll WwTW Storm Overflow Menai Strait 34 92h 15m -
Dwr Cymru Welsh Water Rhosybol Gorslwyd Storm Overflow Unnamed Watercourse 27 90h -
Dwr Cymru Welsh Water London Road Valley Storm Overflow Unnamed Watercourse 12 87h 30m -
Dwr Cymru Welsh Water Holyhead Porth Y Felin Storm Overflow Unnamed Ditch draining to New Harbour 9 77h 30m -
Dwr Cymru Welsh Water Star Gaerwen Storm Overflow Afon Braint 9 68h 30m -
Dwr Cymru Welsh Water Copperfield Close Four Mile Bridge Storm Overflow Holy Island Straits South 6 65h 15m -
Dwr Cymru Welsh Water Llanfaelog Storm Overflow Llyn Maelog 6 54h 28m -
Dwr Cymru Welsh Water Pont Y Crug Llanddaniel Storm Overflow Afon Braint 14 47h 48m -
Dwr Cymru Welsh Water Gorsllwyd Llanddona Storm Overflow Afon Cadnant 8 46h 34m -
Dwr Cymru Welsh Water Gorad Beach Road Storm Overflow Estuarial Waters of Afon Alaw 5 33h 58m -
Dwr Cymru Welsh Water Benllech WwTW Storm Overflow Coastal Waters - Benllech 12 33h -
Dwr Cymru Welsh Water Lon Fain Dwyran Storm Overflow River Braint 4 32h -
Dwr Cymru Welsh Water Waterside Holyhead Storm Overflow New Harbour, Holyhead 14 30h 15m -
Dwr Cymru Welsh Water Beaumaris & Llanfaes WwTW Storm Overflow Menai Strait 12 29h 45m -
Dwr Cymru Welsh Water Newborough WwTW Storm Overflow Afon Braint 9 24h 38m -
Dwr Cymru Welsh Water Menai Ville Storm Overflow Menai Strait 11 20h -
Dwr Cymru Welsh Water Menai Bridge Faelog Causeway 1 Overflow Menai Strait 11 20h -
Dwr Cymru Welsh Water Afon Goch Lon Parys Amlwch Storm Overflow Afon Goch 4 14h 15m -
Dwr Cymru Welsh Water Llangoed Lleiniog Overflow Menai Strait 5 13h 12m -
Dwr Cymru Welsh Water Holyhead Turkey Shore Storm Overflow Old Harbour Holyhead 8 13h -
Dwr Cymru Welsh Water Menai Suspension Bridge No 3 Overflow Menai Strait 9 10h 45m -
Dwr Cymru Welsh Water Menai Bridge Suspension Storm Overflow Menai Strait 9 10h 45m -
Dwr Cymru Welsh Water Lon Sardis Storm Overflow River Cefni 10 10h 21m -
Dwr Cymru Welsh Water London Road Valley no.2 Storm Overflow Unname Watercourse 6 8h 45m -
Dwr Cymru Welsh Water Prince of Wales Road Storm Overflow New Harbour, Holyhead 10 7h 30m -
Dwr Cymru Welsh Water Holyhead Bae Trearthur No1 Storm Overflow Estuarial Waters of the Inland Sea 5 6h 45m -
Dwr Cymru Welsh Water Rhosneigr Overflow Irish Sea 1 5h 15m -
Dwr Cymru Welsh Water Ffordd Y Traeth Cemaes Bay Storm Overflow Cemaes Bay 1 3h 45m -
Dwr Cymru Welsh Water Fryars Bay Llanfaes Overflow Menai Strait 2 3h 15m -
Dwr Cymru Welsh Water Moelfre Car Park Storm Overflow Coastal Waters of the Irish Sea 1 2h 45m -
Dwr Cymru Welsh Water Holyhead WwTW Overflow Unnamed Watercourse 2 1h 45m -
Dwr Cymru Welsh Water Rhosneigr Storm Overflow Coastal Waters - Irish Sea 1 1h 45m -
Dwr Cymru Welsh Water Fford Cae Sel Storm Overflow Drainage Ditch 3 1h 29m -
Dwr Cymru Welsh Water Pont y Brenin Overflow Afon y Brenin 3 1h 29m -
Dwr Cymru Welsh Water Gwalchmai WwTW Storm Overflow Nant Cwyrtai 2 1h 3m -
Dwr Cymru Welsh Water Malltraeth WwTW Inlet Storm Overflow Cefni Estuary 1 1h 2m -
Dwr Cymru Welsh Water Llandegfan Rhianfa Overflow Menai Strait 2 0h 59m -
Dwr Cymru Welsh Water Cycle Way Llangefni Storm Overflow Afon Cefni 3 0h 42m -
Dwr Cymru Welsh Water Glyn Garth Overflow Menai Strait 1 0h 33m -
Dwr Cymru Welsh Water Holyhead Morawelon Storm Overflow Outer Harbour, Holyhead 7 0h 22m -
Dwr Cymru Welsh Water Beaumaris West End Overflow Menai Strait 1 0h 15m -
Dwr Cymru Welsh Water Menai Bridge Porth Wrach No 2 Overflow Menai Strait 0 0h -
Dwr Cymru Welsh Water Unknown Unknown 0 0h -
Dwr Cymru Welsh Water Plas Y Ffrwd Rhosybol Storm Overflow River Alaw 0 0h -
Dwr Cymru Welsh Water Bodedern Main Storm Overflow River Alaw 0 0h -
Dwr Cymru Welsh Water Holyhead Hibernia Row Storm Overflow New Harbour, Holyhead 0 0h -
Dwr Cymru Welsh Water Llanfair PG Anglesey No 2 Storm Overflow Menai Strait 0 0h -
Dwr Cymru Welsh Water Arosfa Road Dwyran Storm Overflow Afon Braint 0 0h -
Dwr Cymru Welsh Water Llansadwrn Anglesy Storm Overflow Afon Cadnant 0 0h -
Dwr Cymru Welsh Water Holyhead Bae Trearthur No2 Storm Overflow Unnamed Watercourse 0 0h -
Dwr Cymru Welsh Water Llanfaes Overflow Unnamed Watercourse 0 0h -
Dwr Cymru Welsh Water Unknown Unknown 0 0h -
Dwr Cymru Welsh Water Lon Gardener Valley Overflow Unnamed Watercourse 0 0h -
Dwr Cymru Welsh Water Llangoed Cynlais Overflow Coastal Waters 0 0h -
Dwr Cymru Welsh Water Brynsiencyn Main Storm Overflow Menai Strait 0 0h -
Dwr Cymru Welsh Water Llangefni Main Storm Overflow Afon Cefni 0 0h -
Dwr Cymru Welsh Water Unknown Unknown 0 0h -
Dwr Cymru Welsh Water Brynsciencyn Overflow Menai Strait 0 0h -
Dwr Cymru Welsh Water Malltraeth Overflow Afon Cefni 0 0h -
Dwr Cymru Welsh Water Llangefni WwTW Storm Overflow Afon Cefni 0 0h -
Dwr Cymru Welsh Water Aberffraw Storm Overflow River Ffraw 0 0h -
Dwr Cymru Welsh Water Gwalchmai Isaf Storm Overflow Unnamed Watercourse 0 0h -
Dwr Cymru Welsh Water Pentraeth Tan Y Graig Storm Overflow River Nodwydd 0 0h -
Dwr Cymru Welsh Water Gaerwen WwTW Storm Overflow Afon Cefni 0 0h -
Dwr Cymru Welsh Water Amlwch Port Storm Overflow Coastal Waters - Amlwch Harbour 0 0h -
Dwr Cymru Welsh Water Malltraeth WwTW Storm Overflow Cefni Estuary 0 0h -
Dwr Cymru Welsh Water High Street Malltraeth Storm Overflow Afon Cefni 0 0h -
Dwr Cymru Welsh Water Unknown Unknown 0 0h -
Dwr Cymru Welsh Water Bae Trearthur Isallt Bach Overflow Caernarfon Bay North 0 0h -
Dwr Cymru Welsh Water Gorwelion Road Newlands Beach Storm Overflow Estuary Afon Alaw 0 0h -
Dwr Cymru Welsh Water Millbank Storm Overflow Unnamed Watercourse 0 0h -
Dwr Cymru Welsh Water Benllech Old Tidal Tanks Storm Overflow Coastal Waters - Benllech 0 0h -
Dwr Cymru Welsh Water Llanerchymedd WwTW Storm Overflow River Alaw 0 0h -
Dwr Cymru Welsh Water Bae Trearthur Lon Isallt Storm Overflow Adjacent Ditch 0 0h -
Dwr Cymru Welsh Water Penrhos Beach Holyhead Storm Overflow Beddmanarch Bay 0 0h -
Dwr Cymru Welsh Water Llansadwrn Anglesey Storm Overflow Tributary of Afon Cadnant 0 0h -
Dwr Cymru Welsh Water Beaumaris Green Overflow Estuarial Waters 0 0h -
Dwr Cymru Welsh Water Unknown Unknown 0 0h -
Dwr Cymru Welsh Water Beaumaris Green Storm Overflow Menai Strait 0 0h -

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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