Overflow history upstream of River Severn in Shrewsbury
The spot's forecast · For event organisers
This page lists the monitored storm overflows upstream of this spot and how often each spilled in each year. It is not a water test, and it does not say whether the water is fit to swim in. It does not include farm runoff, misconnected drains, treated sewage effluent, wildlife or overflows without a monitor. A year's count depends on how long the monitor worked, shown as monitor uptime.
Each year, all overflows upstream
| Year | Overflows with a return | Spills | Spill hours | Spill hours, weighted by reach |
|---|---|---|---|---|
| 2021 | 11 | 373 | 2,868 | 1,446 |
| 2022 | 13 | 404 | 1,795 | 1,319 |
| 2023 | 14 | 634 | 6,778 | 3,203 |
| 2024 | 14 | 517 | 3,758 | 411 |
| 2025 | 15 | 370 | 2,099 | 214 |
Reach is the share of a spill's bacteria SwimSignal's model expects to arrive here, after die-off on the way and dilution by the river. Weighting by it counts an hour of spilling just upstream for far more than one 40 km away. Spills are counted by the Environment Agency's 12/24 method: any discharge in the first 12 hours counts as one spill, then one more for each 24 hours with any discharge. How reach is worked out.
The overflows, by reach
All 15, the one whose spills matter most here first. Hours away is how long sewage takes to arrive at the model's river speed.
| Overflow and id | Company | km upstream | Hours away | Reach | Spills 2023 | Spills 2024 | Spills 2025 | Spill hours 2025 | Monitor uptime 2025 |
|---|---|---|---|---|---|---|---|---|---|
| Frankwell, White Horse Passage storm overflow Frankwell - White Horse Passage (CSO) · SVT02540 | Severn Trent Water | 0.0 | under 1 | 100% | 3 | 7 | 4 | 1 | 100% |
| Shrewsbury, Smithfield Rd/Roushill storm overflow Shrewsbury -Smithfield RD/Roushill (CSO) · SVT02073 | Severn Trent Water | 0.1 | under 1 | 99% | 38 | 11 | 16 | 8 | 100% |
| Shrewsbury, 5 Severn Terrace storm overflow Shrewsbury - 5 Severn Terrace (CSO) · SVT00007 | Severn Trent Water | 0.3 | under 1 | 98% | 103 | 57 | 38 | 34 | 100% |
| Shrewsbury, Coton Hill 75 storm overflow Shrewsbury - Coton Hill 75 (CSO) · SVT02727 | Severn Trent Water | 0.4 | under 1 | 98% | – | – | 22 | 10 | 99% |
| Shrewsbury, Castle Foregate storm overflow Shrewsbury - Castle Foregate (CSO) · SVT00490 | Severn Trent Water | 0.6 | under 1 | 97% | 72 | 63 | 29 | 51 | 99% |
| Shrewsbury, Coton Hill (The Flash) storm overflow Shrewsbury - Coton Hill (THE Flash) (CSO) · SVT00643 | Severn Trent Water | 0.9 | under 1 | 96% | 48 | 18 | 23 | 7 | 100% |
| Shrewsbury, The Mount/Thornhill Rd storm overflow Shrewsbury -THE Mount/Thornhill RD (CSO) · SVT02306 | Severn Trent Water | 3.4 | 2 | 84% | 5 | 12 | 25 | 47 | 100% |
| Bicton, The Oval storm sewage overflow Bicton - THE Oval (SSO) · SVT02299 | Severn Trent Water | 15.2 | 8 | 34% | 25 | 42 | 22 | 160 | 88% |
| Pant-Plas Cerrig sewage works overflow Pant-Plas Cerrig (STW) · SVT01754 | Severn Trent Water | 50.9 | 28 | 1% | 24 | 41 | 18 | 150 | 100% |
| Bomere Heath sewage works storm tank overflow Bomere Heath STW (Ssto) · SVT00304 | Severn Trent Water | 10.7 | 6 | 1% | 50 | 72 | 62 | 998 | 100% |
| Baschurch, Walford Heath pumping station overflow Baschurch - Walford Heath SPS (EO) · SVT02424 | Severn Trent Water | 12.9 | 7 | 1% | 36 | 35 | 15 | 107 | 98% |
| Oswestry, Knockin sewage works overflow Oswestry - Knockin STW IPS (CSO) · SVT01303 | Severn Trent Water | 39.6 | 22 | <1% | 69 | 42 | 38 | 58 | 89% |
| West Felton sewage works overflow West Felton STW (CSO & EO) · SVT02510 | Severn Trent Water | 42.3 | 24 | <1% | 15 | 8 | 5 | 54 | 100% |
| Mile Oak sewage works storm tank overflow Mile OAK STW (Ssto) · SVT01737 | Severn Trent Water | 58.9 | 33 | <1% | 122 | 85 | 40 | 302 | 100% |
| Morda, Weston Road storm overflow Morda - Weston Road (CSO) · SVT02521 | Severn Trent Water | 59.8 | 33 | <1% | 24 | 24 | 13 | 113 | 98% |
A dash: no annual return for that overflow in that year.
Sources and credits
Storm overflow annual returns: © Environment Agency copyright and/or database right 2025, Open Government Licence v3.0. Overflow positions: the water companies via the National Storm Overflow Hub, CC BY 4.0. River network: contains OS data © Crown copyright and database right 2026 (OS Open Rivers). Traced and weighted by SwimSignal (swimsignal.co.uk), whose method is at swimsignal.co.uk/methods.html. All credits and licences.