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Dwr Cymru Welsh Water · overflow Gellilydan WwTW Settled Storm Overflow

No active event

Afon Tafarn-helyg

Recorded by the operator as Tributary of the Afon Tafarn Helyg. The outfall is 2 m from the Afon Tafarn-helyg on the Ordnance Survey river network, which is the river this page groups it under.

The monitor for overflow Gellilydan WwTW Settled Storm Overflow (operator listed as Dwr Cymru Welsh Water) reports no current spill. The data records 37 spill events totalling 19 h in the last 30 days.

📍 52.94180°, -3.95511°

Spill record· since 6 May 2026

49

spill events

27h

cumulative discharge

4.3 h

longest single event

2026-06-11

first event on record

In the last 30 days this overflow recorded 19h of discharge. Across Dwr Cymru Welsh Water's 2,359 monitored overflows the median was 0h. This site is in the top 5% by 30-day spill duration.

Recent spill events· last 30 days

The operator's own annual returns· 2021 to 2025

What the water company itself reported in its annual returns for this overflow, year by year, as republished by The Rivers Trust. Hours are the total reported discharge duration; monitor working is the share of the year the event monitor was operating (a figure of 0% may mean no usable monitoring data rather than no spills). These figures are the operator's own reporting, not our measurement, and our live record above begins on 6 May 2026.

YearSpills countedHoursMonitor workingMatched by
2021101960h100%location, 84 m (medium confidence)
2022110802h100%location, 16 m (high confidence)
20231381,486h99%location, 16 m (high confidence)
202487764h99%location, 16 m (high confidence; 2 rows at this location added together)
202581608h100%location, 16 m (high confidence)

Source: the operator's annual returns, as republished by The Rivers Trust (Event Duration Monitoring, storm overflows, 2021 to 2025, England and Wales). Contains public sector information licensed under the Open Government Licence v3.0. Produced by The Rivers Trust. © Environment Agency copyright and/or database right 2025. All rights reserved. © Dwr Cymru/Welsh Water. © Hafren Dyfrdwy. The rows carry no identifier shared with our overflow list, so each is matched by location: the nearest row within 150 m, or by permit reference where a year could not be placed. The distance is shown per row, nothing is forced, and where several rows sit at one location their figures are added together. Years where the match is uncertain, or close to another overflow's row, are left out here rather than risk showing another overflow's figures.

How we keep the record.

Nearby water quality· 0 sampling points within 5 km

No surface-water sampling points within 5 km.

Take action

The record above is verifiable from public Environment Agency and water-company data. Three official accountability channels — pre-filled with the evidence on this page.

Are you here right now?

If you can see foam, sewage debris, dead fish, or smell something wrong — submit a citizen report. Confirmed reports are added to the Truth Engine and strengthen the public record on this overflow.

📷 Report what you saw →

1. Complain to Dwr Cymru Welsh Water

The official complaints route. Most companies require submission through their web form rather than email — open the form, then paste the pre-filled letter.

Open Dwr Cymru Welsh Water complaints formEmail press office instead
Preview the letter
Subject: Storm overflow Gellilydan WwTW Settled Storm Overflow on the Tributary of the Afon Tafarn Helyg: request for information

Dear Dwr Cymru Welsh Water,

I am writing about storm overflow Gellilydan WwTW Settled Storm Overflow on the Tributary of the Afon Tafarn Helyg.

Environment Agency storm overflow monitoring data for overflow Gellilydan WwTW Settled Storm Overflow on the Tributary of the Afon Tafarn Helyg (operator listed as Dwr Cymru Welsh Water) records 37 spill events starting between 17 September 2026 and 17 October 2026; the 28 with a published end time total 19 h. The most recent recorded event started on 10 October 2026 at 10:15 UTC.

As of 17 October 2026 at 22:25 UTC, the monitor does not report the overflow as spilling.

Further details from the public record:
- On the Afon Tafarn-helyg, per the OS Open Rivers network (Ordnance Survey, Open Government Licence)
- Location: 52.94180, -3.95511
- Sources: Environment Agency National Storm Overflow Hub and Water Quality Archive (Open Government Licence v3.0), cross-referenced via River Truth (https://rivertruth.co.uk/overflow/14317)

These figures are taken from public monitoring data as published and may be revised by the publisher. They are not a finding that any permit condition has been breached.

[Add your personal context here, for example how you use this stretch of water.]

Please could you tell me:
1. Whether the monitoring record summarised above is accurate and complete
2. What caused the recorded spill events
3. What work, if any, is planned at this overflow, and on what timeline
4. What measures are in place to reduce spills from this overflow in future

[Delete if not applicable: I have copied the Environment Agency, Ofwat and my MP into this correspondence.]

Yours faithfully,
[Your name]
[Your address]
[Your customer reference if you are a Dwr Cymru Welsh Water customer]

2. Write to the MP for this stretch

This overflow sits in the Dwyfor Meirionnydd constituency — currently represented by Liz Saville Roberts (Plaid Cymru). Click below to open WriteToThem with the letter copied to your clipboard — paste it into the message box.

Write to Liz Saville Roberts →View MP's contact page →
Or write to your own MP instead

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Preview the letter
Subject: Constituent query: storm overflow Gellilydan WwTW Settled Storm Overflow on the Tributary of the Afon Tafarn Helyg

Dear [your MP, WriteToThem will fill this in],

I am writing as your constituent about public storm overflow monitoring data for our area.

Environment Agency storm overflow monitoring data for overflow Gellilydan WwTW Settled Storm Overflow on the Tributary of the Afon Tafarn Helyg (operator listed as Dwr Cymru Welsh Water) records 37 spill events starting between 17 September 2026 and 17 October 2026; the 28 with a published end time total 19 h. The most recent recorded event started on 10 October 2026 at 10:15 UTC.

As of 17 October 2026 at 22:25 UTC, the monitor does not report the overflow as spilling.

Further details from the public record:
- On the Afon Tafarn-helyg, per the OS Open Rivers network (Ordnance Survey, Open Government Licence)
- Location: 52.94180, -3.95511
- Sources: Environment Agency National Storm Overflow Hub and Water Quality Archive (Open Government Licence v3.0), cross-referenced via River Truth (https://rivertruth.co.uk/overflow/14317)

These figures are taken from public monitoring data as published and may be revised by the publisher. They are not a finding that any permit condition has been breached.

[Add your personal context here, for example how you and your family use this stretch of water.]

I would like to ask:
1. Whether you support strengthening the regulatory regime for storm overflows, and monitor coverage in particular
2. Whether you would raise the monitoring data for this overflow with the Secretary of State for Environment, Food and Rural Affairs, the Environment Agency or Ofwat

Yours sincerely,
[Your name]
[Your address (WriteToThem requires a postal address to verify your constituency)]

MP details are looked up live from the UK Parliament Members API under the Open Parliament Licence v3.0. River Truth makes no claim about this MP's voting or advocacy record on water issues — they are shown solely as the elected representative for this constituency.

3. Report to the Environment Agency

For active pollution incidents — dead fish, foam, sewage on the riverbank — the EA hotline operates 24/7 and triggers a recorded investigation.

📞 0800 80 70 60 (24/7)Report online →
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