Storm overflow register · Yorkshire Water

Bridlington sewage works: storm overflow spills 2025

Bridlington sewage treatment works, run by Yorkshire Water, has 2 monitored storm overflows discharging to North Sea. In 2025 they recorded 108 spills totalling 298 hours, against 92 spills and 406 hours in 2024. By hours spilling, it ranks 139 of 283 Yorkshire Water works, where 1 spilled longest.

Works size: 46,938 population equivalent (BRIDLINGTON STW, UWWTD 2018). Used for the spill volume estimate.

Every spill in 2025

Each blue mark is one spill, placed by when it started and sized by how long it lasted. Hover over a mark for the date and duration.

JanFebMarAprMayJunJulAugSepOctNovDecBridlington STW2 spills, 44.1 h, 1 Jan to 2 Jan20 spills, 30.9 h, 5 Jan to 6 Jan2 spills, 2.5 h, 24 Jan to 24 Jan11 spills, 4.7 h, 26 Jan to 27 Jan5 spills, 1 h, 28 Jan to 28 Jan5 spills, 0.9 h, 20 Feb to 20 Feb5 spills, 0.7 h, 23 Feb to 24 Feb26 Feb 2025 11:16 GMT, 6 min13 Mar 2025 00:08 GMT, 52 min4 spills, 1.5 h, 22 Mar to 22 Mar15 Apr 2025 08:48 GMT, 16.4 h4 spills, 0.8 h, 21 Apr to 21 Apr3 spills, 0.2 h, 22 May to 22 May9 spills, 3.7 h, 24 May to 24 May29 May 2025 08:00 GMT, 4 min8 spills, 0.7 h, 3 Jun to 3 Jun7 Jun 2025 18:56 GMT, 4 min5 spills, 1.1 h, 9 Jun to 10 Jun4 spills, 1.9 h, 2 Jul to 2 Jul3 spills, 2.4 h, 6 Jul to 6 Jul4 spills, 1.4 h, 7 Jul to 7 Jul3 spills, 0.2 h, 16 Jul to 16 Jul15 spills, 3.9 h, 19 Jul to 19 Jul10 spills, 0.8 h, 20 Jul to 20 Jul10 spills, 3 h, 22 Jul to 22 Jul2 spills, 1.6 h, 1 Aug to 1 Aug8 spills, 1.5 h, 4 Aug to 4 Aug2 spills, 1.7 h, 29 Aug to 29 Aug3 spills, 1.2 h, 3 Sep to 3 Sep7 spills, 3.5 h, 4 Sep to 4 Sep2 spills, 2.1 h, 10 Sep to 10 Sep4 spills, 1.3 h, 14 Sep to 15 Sep4 spills, 8.3 h, 20 Sep to 21 Sep3 spills, 1.6 h, 28 Sep to 28 Sep11 spills, 5.8 h, 3 Oct to 3 Oct15 spills, 1.8 h, 19 Oct to 20 Oct2 spills, 3.8 h, 23 Oct to 23 Oct11 spills, 2.3 h, 25 Oct to 25 Oct4 spills, 0.3 h, 27 Oct to 27 Oct3 spills, 0.2 h, 31 Oct to 31 Oct6 spills, 3.2 h, 4 Nov to 4 Nov15 spills, 12.8 h, 10 Nov to 10 Nov2 spills, 0.1 h, 11 Nov to 12 Nov9 spills, 5.4 h, 12 Nov to 13 Nov22 spills, 10 h, 14 Nov to 15 Nov16 spills, 1.5 h, 16 Nov to 17 Nov86 spills, 24.3 h, 18 Nov to 22 Nov23 spills, 7.3 h, 23 Nov to 25 Nov3 spills, 0.2 h, 26 Nov to 26 Nov103 spills, 29.4 h, 28 Nov to 1 Dec3 spills, 5.4 h, 4 Dec to 4 Dec22 spills, 9.2 h, 5 Dec to 7 Dec17 spills, 12.7 h, 8 Dec to 10 Dec3 spills, 0.2 h, 12 Dec to 12 Dec4 spills, 1.6 h, 15 Dec to 15 Dec7 spills, 0.4 h, 16 Dec to 16 Dec11 spills, 7.2 h, 17 Dec to 18 DecBridlington STW5 Jan 2025 10:10 GMT, 2 min6 Jan 2025 08:36 GMT, 2 min9 Jan 2025 15:44 GMT, 2 min9 spills, 0.3 h, 15 Jan to 16 Jan40 spills, 2 h, 20 Jan to 28 Jan7 spills, 0.3 h, 29 Jan to 30 Jan1 Feb 2025 06:58 GMT, 2 min2 Feb 2025 03:48 GMT, 2 min10 spills, 0.4 h, 6 Feb to 8 Feb27 spills, 1 h, 9 Feb to 10 Feb2 Apr 2025 12:20 GMT, 6 min25 Apr 2025 11:48 GMT, 2 min4 Sep 2025 17:14 GMT, 2 min3 spills, 1.5 h, 29 Nov to 29 Nov

Estimated spill volume by month, 2025

Hours spilling each month × the estimated spill rate for a works of this size. The bars are central estimates and the whiskers show the low-high range. Method.

050k100k150k200kJan 2025: 86 h spilling ≈ 69,166 m³ (range 27,550-173,644 m³)JanFeb 2025: 3.1 h spilling ≈ 2,493 m³ (range 993-6,259 m³)FebMar 2025: 2.4 h spilling ≈ 1,930 m³ (range 769-4,846 m³)MarApr 2025: 17 h spilling ≈ 13,914 m³ (range 5,542-34,931 m³)AprMay 2025: 4.0 h spilling ≈ 3,217 m³ (range 1,281-8,076 m³)MayJun 2025: 1.9 h spilling ≈ 1,528 m³ (range 609-3,836 m³)JunJul 2025: 14 h spilling ≈ 10,938 m³ (range 4,357-27,460 m³)JulAug 2025: 4.8 h spilling ≈ 3,860 m³ (range 1,538-9,692 m³)AugSep 2025: 18 h spilling ≈ 14,396 m³ (range 5,734-36,142 m³)SepOct 2025: 14 h spilling ≈ 11,420 m³ (range 4,549-28,671 m³)OctNov 2025: 91 h spilling ≈ 73,348 m³ (range 29,216-184,143 m³)NovDec 2025: 41 h spilling ≈ 33,135 m³ (range 13,198-83,188 m³)Dec
Cubic metres (m³), estimate. Hours are measured by the event duration monitor.

Longest single spills

Started (GMT)OverflowDurationEstimated volume
1 Jan 2025, 00:00Bridlington STW1.8 days14,042 - 88,505 m³
15 Apr 2025, 08:48Bridlington STW16.4 h5,243 - 33,046 m³
5 Jan 2025, 04:22Bridlington STW10.5 h3,374 - 21,268 m³
5 Jan 2025, 16:26Bridlington STW10.4 h3,332 - 20,999 m³
29 Nov 2025, 16:54Bridlington STW9.6 h3,065 - 19,316 m³

Estimated 2025 spill volume and pollution

Estimate, not a measurement. Monitors record how long an overflow spills, not how much. This calculator back-calculates a spill rate from the size of the works, using the Environment Agency's permit formulae, and multiplies it by published storm-sewage concentrations. How it works.

Volume, central estimate239,427 m³range 95,369 - 601,091 m³
In litres239.4 millionrange 95.4 million - 601.1 million L
Olympic swimming pools96at 2,500 m³ each
Organic load, as people's raw sewage359,140person-days of untreated BOD

Assumed spill rate while spilling: 89.0 - 560.9 L/s (central 223.4 L/s), from a dry-weather flow of 89.0 L/s.

Pollutant releasedLowCentralHighConcentration used (low / typical / high)
BOD₅ (organic load) 3,815 kg21,548 kg120,218 kg 40 / 90 / 200 mg/L
Low/high: Europe range, Ellis & Jenkins 2005; typical: UK, Ellis & Jenkins 2005 (both via botturi)
Suspended solids 10,014 kg101,756 kg433,387 kg 105 / 425 / 721 mg/L
Low/high: Europe range; typical: UK, Ellis & Jenkins 2005 (via botturi)
Ammonium-N 181 kg1,508 kg5,590 kg 1.9 / 6.3 / 9.3 mg/L
Low: Germany, Brombach 2005; typical/high: Paris range 3.3-9.3 midpoint and top, Gasperi 2012 (via botturi); no UK value found
Total phosphorus 114 kg623 kg3,246 kg 1.2 / 2.6 / 5.4 mg/L
Low/high: Paris, Gasperi 2012; typical: Slovakia (via botturi). UK figure of 10 mg/L treated as an outlier
E. coli 9.5 trillion organisms239.4 trillion organisms6.0 × 10¹⁵ organisms 10,000 / 100,000 / 1.0 million per 100 mL
Median range at CSO and retention-tank outlets, Stott et al. 2018 (via botturi); typical = log midpoint

Low combines the low spill rate with low concentrations, and high combines high with high, so the true figure is very likely inside the range. Long spills become more diluted as they go on, so the central figure tends to overstate the load of long events. The calculator does not estimate the effect on the receiving water, which depends on river flow or tide at the time of the spill.

Bridlington STW

Inlet overflow at sewage works · discharges to North Sea

Spills 2025
81 (292 hours) · down 10% on 2024
Spills 2024
90 (405 hours)
Long-term average
75.5 spills a year (monitored since 2020)
Monitor uptime
100% of the year
High-spill reason (company)
Performance - SW Infiltration
Investigation
UWWTR investigation ongoing, Operational investigation completed
Improvement
No improvement action in reporting period
Bathing water
Bridlington South Beach
WFD catchment
Yorkshire South (GB640402491000)
Outlet location
TA1929064910 (OS grid reference) · View on Apple Maps
EA ID / permit
YWS01452 · WRA7637 · company name: BRIDLINGTON/STW

Bridlington STW

Inlet overflow at sewage works · discharges to North Sea

Spills 2025
27 (5.9 hours) · up 1250% on 2024
Spills 2024
2 (1.3 hours)
Long-term average
27.0 spills a year (monitored since 2020)
Monitor uptime
87% of the year · Sensor failure / issue
Investigation
UWWTR investigation ongoing, Operational investigation ongoing
Improvement
No improvement action in reporting period
Bathing water
Bridlington South Beach; Wilsthorpe
WFD catchment
Yorkshire South (GB640402491000)
Outlet location
TA1801065600 (OS grid reference) · View on Apple Maps
EA ID / permit
YWS01453 · WRA7637 · company name: BRIDLINGTON/STW

How the estimate works

  1. Dry-weather flow (DWF) = population × water use per person × (1 + infiltration). Water use is 136.5 L per person per day, England's per-capita consumption for 2024-25 [EA]. Infiltration of groundwater into sewers is taken as 0-40% of that flow [Escritt, via HBF]. The Environment Agency defines DWF as PG + I + E [EA].
  2. Population. The size of each works comes from the load entering it as reported under the Urban Waste Water Treatment Directive, in population equivalents (1 p.e. = 60 g of BOD a day) [UWWTD]. We treat population equivalent as population. That overstates flow where trade effluent adds load, and no official source links the two. Works serving fewer than 2,000 p.e. are not reported, so their size has to be entered by hand.
  3. Low spill rate = DWF. This is the method used by Giakoumis & Voulvoulis (2026), which they note likely underestimates storm loads [G&V].
  4. High spill rate = Formula A − flow to full treatment = (DWF + 1360P) − 3DWF. This is the largest flow the permit expects the storm tanks to handle before it passes on to treatment or overflows [EA]. The central rate is the geometric mean of the low and high rates.
  5. Volume = spill rate × hours spilling, with hours taken from the event duration monitor.
  6. Pollution = volume × published storm-sewage concentrations [Botturi et al.] [US EPA]. Organic load is also shown as person-days of untreated sewage at 60 g of BOD per person per day [UWWTD].

What this cannot tell you. It gives no real flow for any single spill, and no effect on the river or sea, which depends on the flow, tide and the other pressures on the water at the time. It gives no figure for spills from overflows on the sewer network, which serve catchments of unknown size. It is a way to put hours into rough physical terms, not a substitute for flow monitoring.

Sources

  1. EA: Water companies - environmental permits for storm overflows and emergency overflows
  2. EA: Water resources 2024 to 2025 - per capita consumption
  3. HBF: Foul sewer design - historic conventions (citing Escritt 1984 on infiltration)
  4. Giakoumis & Voulvoulis (2026), Environ. Sci.: Water Res. Technol., doi:10.1039/D5EW00860C
  5. Botturi et al. (2021), Crit. Rev. Environ. Sci. Technol. 51:1585 - CSO quality review, Table 2
  6. US EPA (2004) Report to Congress on CSOs and SSOs, chapter 4
  7. Urban Waste Water Treatment Directive, Article 2(6): 1 p.e. = 60 g BOD5/day
  8. Olympic-size swimming pool: 2,500 m³ at the nominal 2 m depth

← All Yorkshire Water works · Contains Environment Agency data licensed under the Open Government Licence v3.0. Spill start and stop times: © Environment Agency copyright and/or database right 2026. All rights reserved. They are water-company data and have not been verified by the Environment Agency. Works size: EEA Waterbase UWWTD. How to read the data.