Top of the Poops | Constituency Sewage Map | Cardiff West

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Live data for Cardiff West in 2026

So far this year (as of 18 May 2026, 12:00) there has been 2,532 hours of sewage overflows, from 19 CSO Combined Sewage Overflow - a device that, when operating, pours combined rainwater & sewage into a waterway s

Totals for Cardiff West in 2025

14 Sites polluted by Dwr Cymru Welsh Water

623 sewage dumps

4,635 hours duration

That's 6.44 months. On average 1.7 times a day

Change Over Time

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Waterways in Cardiff West

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Pollution Summary 2025

Here are all the reported sewage overflow totals for Cardiff West 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 all the declared CSO Combined Sewage Overflow - a device that, when operating, pours combined rainwater & sewage into a waterway s appeared to have monitoring enabled for more than 50% of the year

Company	Waterway	Site	Sewage Dumps	Duration (Hours)	Reporting %
Dwr Cymru Welsh Water	Nant Clun	RHIWSAESON STW RHIWSAESON LLANTRI	179	1,254	99.9
Dwr Cymru Welsh Water	Nant Glaswg	CREIGIAU SEWAGE TREATMENT WORKS HOE	72	1,219	99.9
Dwr Cymru Welsh Water	Unknown	St Fagans STW	81	809	99.9
Dwr Cymru Welsh Water	Nant Coslech	Groesfan SPS	71	644	99.8
Dwr Cymru Welsh Water	Nant Dowlais	RHYDLAFAR STW ST FAGANS CARDIFF	87	337	99.9
Dwr Cymru Welsh Water	River Ely	Miskin Sewage Pumping Station Miskin	19	92	99.9
Dwr Cymru Welsh Water	River Ely	CSO at TRELAI PARK STORM SEWAGE PS	31	81	99.9
Dwr Cymru Welsh Water	Nant Henstaff	CREIGIAU PS	32	79	99.9
Dwr Cymru Welsh Water	River Clun	RHIWSAESON STW RHIWSAESON LLANTRI Settled Storm	9	79	100
Dwr Cymru Welsh Water	River Ely	Brynsadler Pumping Station Clun Ely	10	22	99.9
Dwr Cymru Welsh Water	River Ely	Danybryn SPS	9	7	99.9
Dwr Cymru Welsh Water	River Ely	Ely Mill Rd/Muston Rd CSO, Cardiff	14	5	99.9
Dwr Cymru Welsh Water	River Ely	CSO at Cardiff Ely Plymouth Rd No 108	8	2	99.6
Dwr Cymru Welsh Water	River Ely	YNYSDDU PUMPING STATION PONTYCLUN	1	0	99.6
Dwr Cymru Welsh Water	River Ely	Fairview SPS	0	0	98.7
Dwr Cymru Welsh Water	River Ely	MAES YR FELIN PUMPING STATION	0	0	99.9
Dwr Cymru Welsh Water	River Ely	RHYDYNANT PS (ADJ TO 49) PONTYCLUN	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.

Analysing sewage pollution by the Water Industry

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© Openstreetmap contributors, Contains OS data © Crown copyright and database right 2021-2025,
Contains Water UK National Storm Overflow Hub Data CC-BY-SA 4.0 and analysis © 2025 Top-Of-The-Poops

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