Castle Drive Chester Overflow
Storm overflow run by Dwr Cymru Welsh Water, discharging into River Dee.
"Not discharging" means the company's monitor reports no discharge right now — not that the water is clean. The feed publishes status only; no discharge volume is measured.
Year by year
The Environment Agency's official annual returns, counted the EA's way (12/24-hour spills). 2026 is our own running count, the same way, from the live feed since 23 September (when we began keeping every discharge it reports) — so it can only be lower than the full year. The official figure is published next spring.
A spill is the EA's 12/24-hour count: the first 12 hours of a discharge count as one, each further 24 hours with discharge as one more. "Monitor" is the share of that year the monitor was working, so a 0 beside a working monitor is a real zero; "no data" means the monitor produced no usable data that year — not zero. Years before 2024 are matched to this site by name and location, because the EA's site IDs changed that year; a monitor figure beside one of them means the outlet's permit confirms the match.
Other outlets here
Dwr Cymru Welsh Water runs 6 other overflows within 300 m that also discharge into River Dee. They share the sewer and the storm, so one outlet's figures are only part of what reaches the water.
This overflow (Chester Castle Drive): 4 spills in 2025. Distances are between the published outlet points. The names in brackets are Dwr Cymru Welsh Water's own, from its return.
What the 2025 return says
From Dwr Cymru Welsh Water's annual return to the Environment Agency for this overflow.
"High spill threshold not met" means this overflow did not spill often enough to trigger the EA's formal high-spill review for that year. It is not a statement that the spills were harmless.
Discharges we have recorded
36 discharge periods since 24 Feb 2023. 35 of them come from Dwr Cymru Welsh Water's own event-duration-monitoring records (published on Stream, Feb 2023 – Sep 2025); the live feed adds anything after that. The official annual count is the figure to quote.
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Show 26 earlier
| Started | Ended | Discharge time |
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| 1 h 30 min | ||
| 15 min | ||
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| 45 min | ||
| 1 h 0 min | ||
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The year figures above use the EA's 12/24-hour counting method, so they are comparable with the official figures; the monitor log's 39 raw blocks were merged into 36 continuous discharge periods (gaps under 15 min joined).
Rain nearby last 30 days
Nearest live rain gauge: Rainfall gauge nr Thornton le Moors, 10.4 km away. Brown shading = when this overflow was discharging; ▼ = a discharge start.
Overflow shading is a timing match, not proof of cause — heavy rain and spills share a trigger. Times come from the water company’s event-duration monitor (site status only; no discharge volume is published).
Where it is
Tell me when this overflow discharges
One message when the company's monitor reports a new discharge here. At most one every 6 hours.
Setting this alert needs JavaScript. The alerts you already have are on your alerts page.
The alert repeats the monitor's status: whether the overflow is discharging, not how much or why. It can only tell you about a discharge that starts after you turn it on.
Concerned about this overflow?
Report pollution you can see or smell to the regulator straight away; the company handles complaints about the overflow itself.
Write to the MP
The Environment Agency's return places this overflow in the Chester North and Neston constituency. An MP can ask the company and the regulator questions on a constituent's behalf. These words carry the official figures; change them as you like.
The link opens Parliament's own "Find your MP", which gives the MP's name and how to write to them. FloodRadar sends nothing and keeps nothing you write. Check the constituency against your own address: an MP acts only for people who live in it.
Live status: © Dŵr Cymru Welsh Water, from its Storm Overflow Map. Annual spill figures: Environment Agency Event Duration Monitoring return, © Environment Agency copyright and/or database right, Open Government Licence (OGL) v3.0. Spill-event history: © Dŵr Cymru Welsh Water's published EDM start/stop records. Annual figures: The Rivers Trust EDM compilation, © Dŵr Cymru/Welsh Water, Open Government Licence. Times are shown in UK local time. FloodRadar republishes the monitor's status and the EA's figures; it does not measure discharges itself. Constituency and council area from the EA's return: contains OS data © Crown copyright and database right 2026.