Sewage spills in Bristol
Storm overflows near Bristol discharged 3,172 times in 2024, for a combined 7,070 hours across 145 monitored sites.
Includes overflow assets operated by Wessex Water within 5 km of the town centre.
Total spills
3,172
Duration
7,070hrs
Infrastructure
145
Based on the latest Environment Agency storm overflow data
What does 7,070 hours mean?
Combined across all 145 sites in Bristol, that is equivalent to sewage being discharged continuously for 294.6 days non-stop into local waterways (if all reported hours ran back-to-back). In practice, spills are separate events spread across the year.
Top 10 sites by spill count
Sites by severity
- Critical (>100 spills)2
- High (50–100 spills)13
- Moderate (10–49 spills)75
- Low (<10 spills)55
Site details
Counts use the EA 12–24 hour reporting method for the most recent year with spills, per site. Environment Agency EDM dataset.
| Site name | Water company | Spill count | Duration (hours) |
|---|---|---|---|
| Muller Road CSO | Wessex Water | 118 | 645 |
| Filton Avenue CSO | Wessex Water | 111 | 352 |
| Polly Barnes Hill CSO | Wessex Water | 69 | 154 |
| Bishopthorpe Road CSO | Wessex Water | 65 | 133 |
| Ellesmere Road CSO | Wessex Water | 60 | 381 |
What this data does and does not tell you
It counts events, not volume
Event Duration Monitoring records when an overflow ran and for how long. It does not measure how much was discharged, or how diluted it was. A long spill in heavy rain may be far more diluted than a short one in light rain.
Coverage has improved sharply
Monitors were fitted across almost all storm overflows in England by the end of 2023. Rising spill counts in recent years partly reflect better monitoring, not only worse performance — which is why year-on-year comparisons need care.
Permitted is not the same as harmless
Storm overflows are allowed under environmental permits. Operating within a permit makes a discharge lawful; it does not mean it has no effect on the river or coastline receiving it.
This is a 5 km radius, not a boundary
Sites shown are those within 5 km of the centre of Bristol. Some may discharge into different watercourses, and overflows just outside the radius are not counted.
Seen a pollution incident near Bristol?
Report it to the Environment Agency 24-hour incident hotline on 0800 80 70 60 (England), or Natural Resources Wales on 0300 065 3000. Report it to Wessex Water as well — logging it in both places means the incident exists independently of the operator's own records. Note the time, location and what you saw, and photograph it if you safely can.
Sewage spills in Bristol — common questions
How many sewage spills were there in Bristol?
Monitored storm overflows within 5 km of Bristol recorded 3,172 discharge events in 2024, totalling 7,070 hours across 145 sites. These figures come from Environment Agency Event Duration Monitoring, which water companies are required to fit to storm overflows and report annually.
Why do water companies release sewage near Bristol?
Much of the UK uses a combined sewer system, where rainwater and wastewater share the same pipes. During heavy rain the volume can exceed what the network and treatment works can carry. Storm overflows act as a designed relief valve, releasing diluted sewage into rivers or the sea rather than backing it up into homes and streets. The problem is that they are now used far more often than the system was intended to allow.
Is it legal to discharge sewage into rivers and the sea?
Storm overflows operate under environmental permits, so discharging within those permit conditions is lawful. Discharging outside them — for example in dry weather, or beyond permitted duration — is not, and is enforceable by the Environment Agency. The distinction matters: a high spill count is not by itself evidence of illegality, but it is evidence of a network under strain.
Is it safe to swim near Bristol?
Storm overflow data tells you where and how often discharges happen, not the water quality on a given day. If you swim, check the Environment Agency's designated bathing water classifications for your spot, and short-term pollution alerts before entering. Risk is highest during and for around 48 hours after heavy rainfall. Surfers Against Sewage runs a free real-time alert service for many UK bathing sites.
Who do I report a sewage spill or pollution to?
Report pollution incidents in England to the Environment Agency's 24-hour incident hotline on 0800 80 70 60. In Wales, contact Natural Resources Wales on 0300 065 3000. You can also report the issue to Wessex Water directly, and it is worth doing both so the incident is logged independently of the operator.
Check Bristol tap water quality
DWI lab-style readings, gauges and hardness for this area.
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