Thames Water · overflow TWL00359
No active event
Recorded by the operator as River Blackwater. The outfall is 7 m from the Yateley Common Stream on the Ordnance Survey river network, which is the river this page groups it under.
The monitor for overflow TWL00359 (operator listed as Thames Water) reports no current spill. The data records 1 spill events totalling 30 min in the last 30 days.
📍 51.34099°, -0.80118°
“Rain gauge Camberley, 2.8 km from this overflow, recorded 0 mm in the 24 hours and 4 mm in the 48 hours before this spill started.”
☂ Only 0 mm rainfall in the 24 h before this spill started (recorded at Camberley, 2784 m away)
1
spill event
1h
cumulative discharge
30 min
longest single event
2026-10-18
first event on record
In the last 30 days this overflow recorded 1h of discharge. Across Thames Water's 577 monitored overflows the median was 0h. This site is in the top 5% by 30-day spill duration.
6 other overflows discharge into the River Blackwater (Thames Water area).
0 mm rain in the 24 h before, gauge Camberley, 2.8 km
Rainfall comes from the nearest Environment Agency rain gauge within 10 km, using 15-minute readings rolled into hourly totals. Where a gauge is further away, or too many readings are missing, we say so rather than guess. Rain figures do not show whether a discharge was permitted; that is a matter for the regulator. How we keep the record.
What the water company itself reported to the Environment Agency’s annual returns for this overflow, year by year. 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.
| Year | Spills counted | Hours | Monitor working | Matched by |
|---|---|---|---|---|
| 2024 | 37 | 315h | 100% | hub id |
| 2025 | 10 | 115h | 100% | hub id |
2024, the operator's stated reason: "High spill threshold not met"
2025, the operator's stated reason: "High spill threshold not met"
Source: Environment Agency, Event Duration Monitoring storm overflow annual returns, all years. Matched to this overflow by hub id.
The nearest Environment Agency rain gauge, Camberley, is 2.8 km from this overflow. It recorded 0.0 mm in the last 48 hours.
| Day (UTC) | Rain |
|---|---|
| 18 Oct 2026 | 0.0 mm |
| 17 Oct 2026 | 0.0 mm |
| 16 Oct 2026 | 4.0 mm |
| 15 Oct 2026 | 0.0 mm |
| 14 Oct 2026 | 0.0 mm |
| 13 Oct 2026 | 0.4 mm |
| 12 Oct 2026 | 0.2 mm |
Rainfall comes from 15-minute Environment Agency readings rolled into hourly and daily totals; the 48-hour figure rests on 183 of 192 possible readings. The gauge is 2.8 km from this overflow, so it may not match the rain at the site itself, and the latest day may be incomplete. Rain figures do not show whether a discharge was permitted; that is a matter for the regulator. How we keep the record.
Latest readings at the Environment Agency gauge "Blackwater Bridge", on the River Blackwater, which is 2.1 km from this overflow.
These are the Environment Agency's own gauge readings at the named station, shown for context. The station measures the river, not this overflow, and a reading does not show whether a discharge occurred or was permitted. Trend compares the latest reading with the one nearest 24 hours earlier; a change of 5% or less is shown as steady. How we keep the record.
TH-LSN149 · FRESHWATER - LAKES/PONDS/RESERVOIRS
1.5 km away
No swimmer-relevant measurements available.
TH-LSN389 · FRESHWATER - LAKES/PONDS/RESERVOIRS
1.5 km away
No swimmer-relevant measurements available.
TH-PLDR0012 · FRESHWATER - RIVERS
2.0 km away · last tested 9 weeks ago
TH-PLDR0135 · FRESHWATER - RIVERS
2.1 km away · last tested 7 weeks ago
TH-PLDR0004 · FRESHWATER - RIVERS
3.1 km away · last tested 8 weeks ago
TH-LSN101 · FRESHWATER - LAKES/PONDS/RESERVOIRS
3.5 km away
No swimmer-relevant measurements available.
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.
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 →The official complaints route. Most companies require submission through their web form rather than email — open the form, then paste the pre-filled letter.
Subject: Storm overflow TWL00359 on the River Blackwater: request for information Dear Thames Water, I am writing about storm overflow TWL00359 on the River Blackwater. Environment Agency storm overflow monitoring data for overflow TWL00359 on the River Blackwater (operator listed as Thames Water) records 1 spill event starting between 18 September 2026 and 18 October 2026, totalling 30 min. The most recent recorded event started on 18 October 2026 at 01:45 UTC. As of 18 October 2026 at 09:34 UTC, the monitor does not report the overflow as spilling. Further details from the public record: - Open automated data flags on River Truth for this overflow: 1 (comparisons between public datasets, not findings of fault) - On the Yateley Common Stream, per the OS Open Rivers network (Ordnance Survey, Open Government Licence) - Location: 51.34099, -0.80118 - 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/4162) 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 Thames Water customer]
This overflow sits in the Aldershot constituency — currently represented by Alex Baker (Labour). Click below to open WriteToThem with the letter copied to your clipboard — paste it into the message box.
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Subject: Constituent query: storm overflow TWL00359 on the River Blackwater 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 TWL00359 on the River Blackwater (operator listed as Thames Water) records 1 spill event starting between 18 September 2026 and 18 October 2026, totalling 30 min. The most recent recorded event started on 18 October 2026 at 01:45 UTC. As of 18 October 2026 at 09:34 UTC, the monitor does not report the overflow as spilling. Further details from the public record: - Open automated data flags on River Truth for this overflow: 1 (comparisons between public datasets, not findings of fault) - On the Yateley Common Stream, per the OS Open Rivers network (Ordnance Survey, Open Government Licence) - Location: 51.34099, -0.80118 - 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/4162) 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)]
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For active pollution incidents — dead fish, foam, sewage on the riverbank — the EA hotline operates 24/7 and triggers a recorded investigation.