Overflow history upstream of River Thames, Long Bridges, Oxford

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	38	1,564	23,300	298
2022	37	867	10,410	60
2023	43	2,644	37,269	364
2024	44	3,363	49,941	614
2025	44	1,268	16,464	199

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 44, 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
Cassington sewage works overflow Cassington STW · TWL00075	Thames Water	10.3	6	38%	2	22	0	0	100%
Islip sewage works overflow Islip STW · TWL00244	Thames Water	13.5	8	9%	70	61	34	697	100%
Charlton-on-Otmoor sewage works overflow Charlton-on-Otmoor STW · TWL00085	Thames Water	18.4	10	5%	77	120	54	814	100%
Combe sewage works overflow Combe STW · TWL00110	Thames Water	25.3	14	3%	111	130	30	356	100%
Upper Heyford sewage works overflow Upper Heyford STW · TWL00223	Thames Water	36.7	20	3%	44	108	33	302	95%
Woodstock sewage works overflow Woodstock STW · TWL00462	Thames Water	24.4	14	2%	59	41	21	89	99%
Finstock sewage works overflow Finstock STW · TWL00184	Thames Water	33.3	18	2%	29	38	13	144	100%
Charlbury sewage works overflow Charlbury STW · TWL00083	Thames Water	36.8	20	2%	11	22	7	52	100%
Standlake sewage works overflow Standlake STW · TWL00385	Thames Water	26.1	14	2%	131	180	98	2,214	100%
Clifton sewage works overflow Clifton STW · TWL00105	Thames Water	45.5	25	2%	13	36	12	89	100%
The willows, north hinksey lane TWL00411	Thames Water	3.4	2	1%	11	8	7	48	100%
West way, botley (syphon) TWL00439	Thames Water	4.2	2	1%	26	18	10	40	96%
Bampton sewage works overflow Bampton STW · TWL00024	Thames Water	34.0	19	1%	135	160	82	926	99%
Bicester sewage works overflow Bicester STW · TWL00038	Thames Water	25.3	14	1%	66	89	34	450	100%
Weston-on-the-Green sewage works overflow Weston-on-the-Green STW · TWL00443	Thames Water	17.7	10	<1%	63	86	42	696	100%
Middle Barton sewage works overflow Middle Barton STW · TWL00298	Thames Water	36.1	20	<1%	17	44	15	152	100%
Weston-on-the-Green pumping station overflow Weston-on-the-Green SPS · TWL00442	Thames Water	17.7	10	<1%	0	3	2	21	100%
Stanton Harcourt sewage works overflow Stanton Harcourt STW · TWL00389	Thames Water	17.0	10	<1%	91	123	42	709	100%
Carterton sewage works overflow Carterton STW · TWL00074	Thames Water	40.1	22	<1%	61	57	25	404	100%
Grendon Underwood sewage works overflow Grendon Underwood STW · TWL00204	Thames Water	35.4	20	<1%	76	68	31	306	100%
Bledington sewage works overflow Bledington STW · TWL00042	Thames Water	56.8	32	<1%	65	114	50	947	100%
Church Hanborough sewage works overflow Church Hanborough STW · TWL00098	Thames Water	15.5	9	<1%	120	158	88	1,236	100%
South Leigh sewage works overflow South Leigh STW · TWL00377	Thames Water	18.4	10	<1%	96	71	49	927	100%
Beckley sewage works overflow Beckley STW · TWL00113	Thames Water	18.9	10	<1%	22	10	4	24	100%
Middleton Stoney sewage works overflow Middleton Stoney STW · TWL00300	Thames Water	30.7	17	<1%	37	55	18	145	100%
Tackley & Storm pumping station overflow Tackley SPS & Storm SPS · TWL00403	Thames Water	27.3	15	<1%	1	30	4	47	100%
Bletchingdon sewage works overflow Bletchingdon STW · TWL00043	Thames Water	27.7	15	<1%	120	120	32	302	95%
Marsh Gibbon sewage works overflow Marsh Gibbon STW · TWL00294	Thames Water	31.3	17	<1%	99	69	22	208	99%
Milton-Under-Wychwood sewage works overflow Milton-Under-Wychwood STW · TWL00303	Thames Water	50.4	28	<1%	126	152	67	1,091	100%
Chadlington sewage works overflow Chadlington STW · TWL00079	Thames Water	42.2	23	<1%	64	84	35	362	100%
Clanfield sewage works overflow Clanfield STW · TWL00103	Thames Water	39.3	22	<1%	150	172	14	185	97%
Ludgershall sewage works overflow Ludgershall STW · TWL00283	Thames Water	32.9	18	<1%	98	99	52	616	100%
Witney sewage works overflow Witney STW · TWL00457	Thames Water	36.4	20	<1%	119	141	37	576	100%
Faringdon sewage works overflow Faringdon STW · TWL00180	Thames Water	44.9	25	<1%	116	138	50	159	94%
Lechlade sewage works overflow Lechlade STW · TWL00263	Thames Water	51.8	29	<1%	45	128	11	161	100%
Bloxham sewage works overflow Bloxham STW · TWL00045	Thames Water	57.7	32	<1%	94	71	28	349	100%
XX CSO TWL00575	Thames Water	45.0	25	<1%	34	70	49	54	100%
XX (Bucknell) pumping station overflow XX (Bucknell) SPS · TWL00498	Thames Water	31.5	18	<1%	–	7	0	0	94%
Kings Sutton sewage works overflow Kings Sutton STW · TWL00255	Thames Water	52.2	29	<1%	16	36	6	45	98%
Kempsford sewage works overflow Kempsford STW · TWL00246	Thames Water	58.3	32	<1%	8	8	0	0	100%
Banbury sewage works overflow Banbury STW · TWL00025	Thames Water	57.8	32	0%	79	126	26	314	96%
The Mill (Kingham) pumping station overflow The Mill (Kingham) SPS · TWL00252	Thames Water	57.9	32	0%	18	23	17	80	100%
Middleton Cheney sewage works overflow Middleton Cheney STW · TWL00299	Thames Water	59.0	33	0%	19	53	13	122	100%
Cherwell Street (Banbury) & SSP pumping station overflow Cherwell Street (Banbury) SPS & SSP · TWL00281	Thames Water	59.1	33	0%	5	14	4	4	100%

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.