Thornbury Sewage Treatment Works
Storm overflow run by Wessex Water, discharging into Severn Estuary.
"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 Wessex Water's monitor log. The feed reports only each overflow's latest discharge, so a discharge it moved past before we saw it end is counted as one spill with no hours: the hours are a floor. 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.
What the 2025 return says
From Wessex Water's annual return to the Environment Agency for this overflow.
This overflow spilled often enough to trigger the EA's high-spill review; the review line is the company's own stated reason.
Discharges we have recorded
31 discharge periods since 5 Jan 2025, 3 whose end the feed never gave. 30 of them come from Wessex Water's own event-duration-monitoring records (published on Stream, Jan 2025 – Feb 2026); this overflow has no live feed, so nothing after that log is held. The official annual count is the figure to quote.
-
not captured
-
2 d 6 h
-
10 min
-
11 h 58 min
-
5 d 16 h
-
16 d 10 h
-
1 d 18 h
-
1 h 8 min
-
1 d 2 h
-
7 d 5 h
Show 21 earlier
| Started | Ended | Discharge time |
|---|---|---|
| 17 h 18 min | ||
| 7 d 22 h | ||
| 15 h 48 min | ||
| 17 h 14 min | ||
| 8 d 6 h | ||
| 14 h 36 min | ||
| 16 h 58 min | ||
| 2 min | ||
| 1 h 16 min | ||
| 2 min | ||
| 6 min | ||
| 4 min | ||
| 17 h 52 min | ||
| 22 min | ||
| 13 h 36 min | ||
| 3 d 0 h | ||
| 3 h 18 min | ||
| 4 min | ||
| 5 h 46 min | ||
| 9 h 58 min | ||
| 3 d 21 h |
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 161 raw blocks were merged into 31 continuous discharge periods (gaps under 15 min joined).
Rain nearby last 30 days
Nearest live rain gauge: Rainfall gauge nr Cromhall, 6.5 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
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 Thornbury and Yate 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.
Annual spill figures: Environment Agency Event Duration Monitoring return, © Environment Agency copyright and/or database right, Open Government Licence (OGL) v3.0. Storm-overflow spill events: © the respective water company, published on Stream (data.streamwaterdata.co.uk) under CC BY 4.0. 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.